Yang Dan   Huang Yongqing   Liu Tao   Ma Xiaokai   Duan Xiaofeng   Liu kai   Ren Xiaomin  

      摘要 + 此论文可免费阅读 (可能需要登录)

We have designed and fabricated zero-bias operational two-element symmetric-connected photodetector arrays (SC-PDA). The designed SC-PDA have higher saturation currents, larger RF power, and better frequency responses than the single PD under zero bias. The bias-free SC-PDA with 15 μm diameter of each PD demonstrated a 3 dB bandwidth of 19.4 GHz at 0.5 mA. The RF saturation photocurrent and maximum RF output power of the SC-PDA with 40 μm, 50 μm, and 60 μm diameter under zero bias is over 9.31 mA and -5.86 dBm at 3 GHz, 14.52 mA and 1.17 dBm at 1GHz, 13.72 mA and -1.76 dBm at 1 GHz, respectively.

       PDF全文        Chinese Optics Letters ，2020年第18卷第1期 pp.01      

Cheng Jiaju   Luo Jianwen  

      摘要 + 此论文可免费阅读 (可能需要登录)

For fluorescence molecular tomography (FMT), image-quality could be improved by incorporating sparsity constrain. L1 norm regularization method is proved better than L2 norm like Tikhonov regularization. However, Tikhonov method was found capable of achieving similar quality at high iteration cost by adopting zeroing strategy. By studying the reason, a Tikhonov-regularization-based projecting sparsity pursuit method was proposed which reduces the iterations significantly and achieves good image-quality. It was proved in phantom experiments through time-domain FMT that the method could obtain higher accuracy and less over-sparsity and is more applicable for heterogeneous-target reconstruction, compared with several regularization methods implemented in this paper.

       PDF全文        Chinese Optics Letters ，2020年第18卷第1期 pp.01      

Saadon Haitham   Abbas Saeed   Shubar Mohammed  

      摘要 + 此论文可免费阅读 (可能需要登录)

Bi2S3-xSex/PMMA nanocomposite films were prepared using a microwave assisted synthesis with different compositions of x. Crystal structure, surface morphology, and optical properties were performed to characterize the prepared nanocomposite films. The crystallinity and optical band gap of the prepared Bi2S3-xSex/PMMA were affected by x. The prepared samples showed a blue shift in the absorption edge. The laser power dependent nonlinear refraction and absorption of Bi2S3-xSex/PMMA nanocomposite films were investigated by using the Z-scan technique. The optical nonlinearity of the nanocomposite films exhibited switchover from negative nonlinear refraction to positive nonlinear refraction to negative nonlinear refraction effect, and from saturable absorption to reverse saturable absorption to saturable absorption with increase and decrease in the composition. An interesting of all-optical figures of merit was reported to assess the nanocomposite films for a practical device. It were calculated the device all-figures of merit based on the nonlinear response, which is important for all-optical switching device. The results demonstrate that the optimized all-optical figures of merit can be achieved by adjusting the composition and input laser power, which can be used for the design of different all-photonic devices, as well as the results of nonlinear switching behavior can be open new possibility of using the nanocomposite films in laser Q-switching and mode-locking.

       PDF全文        Chinese Optics Letters ，2020年第18卷第1期 pp.01      

Gao Yachen   Shuang Chen   Suying Yang   Huang Yan   Weiyan Jiao   Guanghua Fan  

      摘要 + 此论文可免费阅读 (可能需要登录)

The dipole resonances of gold nanocages were investigated theoretically using finite difference time domain (FDTD). The results show that field enhancement is obtained at the walls of the gold nanocages. It is believed that the effect can cause strong optical nonlinear property. To test the hypothesis, the nonlinear absorption was investigated using broadband 5ns Z-scan. It was found that, at low intensities the sample shows saturation absorption (SA), while at higher intensities, a switch from SA to reverse saturation absorption (RSA) occurs. Moreover, the nonlinear absorption of sample is sensitively wavelength-dependent, and in resonant region saturation intensity is the largest.

       PDF全文        Chinese Optics Letters ，2020年第18卷第1期 pp.01      

Yuan Xupeng   Guo Xinjun   Zhao Miao   Li Yao   Gan Zongsong   Ruan Hao  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this Letter, new approach of optical tape for high capacity multilayer data storage is proposed. We show that a length of 5 cm and width of 2 cm soft and transparent optical tape can be used for two-photon three-dimensional bit data storage. We successfully demonstrate writing and reading of six layers of data storage with a transverse bit separation of 2 μm and an axial separation of 2.5 μm in a tetraphenylethylene-doped photobleaching polymer. Thus, the optical tape what we put forward in the experiment can help people realize true big data storage in the future likes magnetic tape. This method significantly paves a novel way for solving big data storage problem.

       PDF全文        Chinese Optics Letters ，2020年第18卷第1期 pp.01      

Xiao ZhiLei   Quan Wei   Xu SongPo   Yu ShaoGang   Wang YanLan   Zhao Meng   Wei MingZheng   Zhou Yu   Lai Xuan-yang   Chen(陈京) Jing   Liu Xiaojun  

      摘要 + 此论文可免费阅读 (可能需要登录)

Coulomb potential may induce a significant angular offset to the 2-dimensional photoelectron momentum distributions for atoms subject to strong elliptically polarized laser field. In the attoclock experiment, this offset usually cannot easily be disentangled from the contribution of tunneling delay and poses a main obstacle to the precise measurement of tunneling delay. Based on semiclassical calculations, here we propose a method to extract the equivalent temporal offset induced solely by Coulomb potential (TOCP) in an attoclock experiments. Our calculations indicate that, at constant laser intensity, the TOCP show distinctive wavelength dependence laws for different model atoms and the ratio of the target atom's TOCP to that of H becomes insensitive to wavelength and linearly proportional to (2I_p )^(-3⁄2), where I_p is the ionization potential of the target atom. This wavelength and I_p dependence of TOCP can be further applied to extract the Coulomb potential influence. Our work paves the way for an accurate measurement of the tunneling delay in the tunneling ionization of atoms subject to intense elliptically polarized laser field.

       PDF全文        Chinese Optics Letters ，2020年第18卷第1期 pp.01      

Fan Haibo   Mu Yining   Liu ChunYang   zhu yan   Liu Guozhen   Wang Shuai   Li Yanzheng   Du Peng  

      摘要 + 此论文可免费阅读 (可能需要登录)

Aiming at the application requirements of information optics, this paper proposed a perovskite quantum dot random lasing pumping method suitable for high-speed modulation. At the same time, the luminescence characteristics of perovskite quantum dot films under electron beam pumping conditions are analyzed, and the random lasing mechanism of electron beam pumping CsPbBr3 quantum dot films is revealed. Finally, It is confirmed that perovskite quantum dots are easy to realize random lasing under electron beam pumping conditions.

       PDF全文        Chinese Optics Letters ，2020年第18卷第1期 pp.01      

Li Zhenhua   Cheng Chuanfu   liu Hanping   Li Dawei   Xu Shicai   Liu Huilan   Zhang Junye   Zhang Suzhen  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this Letter, we fabricate integrated metasurface of encoded dynamic phases and experimentally generate nonconventional Kagome-type lattices of no second-order phase vortices. The thin metasurface acts analogous to an integration of three conventional optical elements, i.e., six pinholes located at the vertices of two concentric regular triangles of size ratio 1:2, six transparent discs of different thicknesses to introduce a total phase shift difference of 6π and a Fourier lens with focal length in micro-scale. Kagome lattice with required vortex distribution is realized at the “focal” plane of the metasurface under illumination of plane wave.

       PDF全文        Chinese Optics Letters ，2020年第18卷第1期 pp.01      

Zhang Chi   Fu Dongying   Xia Chunli   Yao Lishuang   Lu Chunlian   Sun weimin   Liu Yongjun  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this paper, a dye-doped cholesteric liquid crystal (DDCLC) filled hollow glass microsphere is demonstrate to be a resonator with good temperature response. A diglycerol layer is used to wrap the DDCLCs microdroplet to keep it steady and control its orientation. The whispering gallery mode (WGM) lasing and photonic band gap (PBG) lasing caused by two different mechanisms were obtained under the pump of a pulsed laser, and the temperature response of these two kind of lasing were studied. For the liquid crystal and chiral material used in this paper, both the WGM lasing and the PBG lasing have a blue shift in wavelength with increasing temperature.

       PDF全文        Chinese Optics Letters ，2020年第18卷第1期 pp.01      

Cao Liang   YU Yang   Xiao Min   Yang Junbo   Zhang Xue-liang   Meng Zhou  

      摘要 + 此论文可免费阅读 (可能需要登录)

In order to meet the practical needs of all-fiber CTD sensor with high sensitivity, compact structure and easy packaging, this paper uses a microfiber coupler combined with Sagnac loop (MCSL) reflective photonic device to conduct salinity, temperature and deep sensing experiments.These MCSLs’ dynamic range and resolution of salinity, temperature, and depth can meet the requirements of actual marine environment monitoring. This structure opens up a new design idea for the practical research of MC-based marine environmental parameter sensor.

       PDF全文        Chinese Optics Letters ，2020年第18卷第1期 pp.01      

Ikawa Shohei   Takada Naoki   Araki Hiromitsu   Niwase Hiroaki   Sannomiya Hiromi   Nakayama Hirotaka   Oikawa Minoru   Mori Yuichiro   Kakue Takashi   Shimobaba Tomoyoshi   Ito Tomoyoshi  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate real-time three-dimensional (3D) color video using color electroholographic system with a cluster of multiple-graphics processing units (multi-GPU) and three spatial light modulators (SLMs) corresponding to respective red, green, and blue (RGB)-colored reconstructing lights. The multi-GPU cluster has a computer-generated hologram (CGH) display node containing a GPU, for displaying calculated CGHs on SLMs, and four CGH calculation nodes using 12 GPUs. The GPUs in the CGH calculation node generate CGHs corresponding to RGB reconstructing lights in a 3D color video using pipeline processing. Real-time color electroholography was realized for a 3D color object comprising approximately 21,000 points per color.

       PDF全文        Chinese Optics Letters ，2020年第18卷第1期 pp.01      

Peng Mingying   wang yafei   li xingyu   wu jiamin   peng xiulin   Cao Jiangkun   Yang Changsheng   Xu Shanhui   Yang Zhongmin  

      摘要 + 此论文可免费阅读 (可能需要登录)

Nd3+ doped fiber lasers at around 900 nm based on the 4F3/2 → 4I9/2 transition have obtained much research attention since they can be used as the laser sources for generating pure blue fiber lasers through frequency doubling technique. Here, all-fiber laser at 915 nm was realized by polarization-maintaining Nd3+ doped silica fiber. A net gain per unit length of up to 1.0 dB/cm at 915 nm was obtained from a 4.5 cm fiber, which to our best knowledge is the highest gain coefficient reported in this kind of silica fiber. The optical-to-optical conversion efficiency varies with active fiber length and the reflectivity of output fiber Bragg grating (FBG), presenting an optimal value of 5.3% at 5.1 cm fiber length and 70% reflectivity of LR-FBG. Additionally, the linear DBR short cavity was constructed to explore its potential in realizing single frequency 915 nm fiber laser. The measurement result of longitudinal mode properties shows it is still multi-longitudinal modes laser operation with 55 mm laser cavity. These results indicate that the Nd3+ doped silica fiber could be used to realize all-fiber laser at 915 nm, which presents potential to be the seed source of high power fiber laser.

       PDF全文        Chinese Optics Letters ，年第卷第期 pp.      

Usman Muhammad   Zabit Usman   D. Bernal Olivier   Raja Gulistan  

      摘要 + 此论文可免费阅读 (可能需要登录)

Self-mixing interferometry (SMI) is an attractive sensing scheme which typically relies on mono-modal operation of employed laser diode. However, change in laser modality can occur due to change in operating conditions. So, detection of occurrence of multi-modality in SMI signals is necessary to avoid erroneous metric measurements. Typically, processing of multi-modal SMI signals is a difficult task due to the diverse and complex nature of such signals. However, the proposed techniques can significantly ease this task by identifying the modal state of SMI signals with 100% success rate, so that interferometric fringes can be correctly interpreted for metric sensing applications.

       PDF全文        Chinese Optics Letters ，2020年第18卷第1期 pp.01      

Ma Rende   Wan Luxue   Liu Xiuhao   Li Xiaoping   JIANG J.F.   夏 云杰  

      摘要 + 此论文可免费阅读 (可能需要登录)

The polarization of D-shaped fiber is modulated after immersing it in the magnetic fluid (MF) and applying a magnetic field. Theoretical analysis predicts that magneto-optical dichroism of MF plays key role in the light polarization modulation. During the light polarization modulation, the evanescent wave polarized parallel to the magnetic field has greater loss than its orthogonal component. The light polarization of D-shaped fiber with a wide polished surface can be modulated easily. High concentration MF and large magnetic field all have great ability to modulate light polarization.

       PDF全文        Chinese Optics Letters ，2020年第18卷第1期 pp.01      

Sait mohammed   Sun Xiaobin   Alkhazragi Omar   Alfaraj Nasir   Kong Meiwei   Ng Tien   Ooi B. S.  

      摘要 + 此论文可免费阅读 (可能需要登录)

Conventional line-of-sight underwater wireless optical communication (UWOC) links suffer from huge signal fading in the presence of oceanic turbulence due to misalignment, which is caused by variations in the refractive index in the water. Non-line-of-sight (NLOS) communication, a novel underwater communication configuration, which has eased the requirements on the alignment, is supposed to enhance the robustness of the UWOC links in the presence of such turbulence. This paper experimentally and statistically studies the impact of turbulence that arises from temperature gradient variations and the presence of different air bubble populations on NLOS optical channels. The results suggest that temperature gradient-induced turbulence causes negligible signal fading to the NLOS link. Furthermore, the presence of air bubbles with different populations and sizes can enhance the received signal power by seizing the scattering phenomena from an ultraviolet 377-nm laser diode.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

FEI CHAO   Hong Xiaojian   Du Ji   Zhang Guowu   Wang Yuan   Shen Xiaoman   Lu Yuefeng   Guo Yang   He Sailing  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this paper, recent advances in underwater wireless optical communication (UWOC) are reviewed for both LED- and LD-based systems, mainly from a perspective of advanced modulation formats. Volterra series based nonlinear equalizers, which can effectively counteract the nonlinear impairments induced by the UWOC system components, are discussed and experimentally demonstrated. Both the effectiveness and robustness of the proposed Volterra nonlinear equalizer in UWOC systems under different water turbidity are validated. To further approach the Shannon capacity limit of the UWOC system, probabilistic constellation shaping (PCS) technique is introduced, which can overcome the inherent gap between a conventional regular quadrature amplitude modulation (QAM) format and the Shannon capacity of the channel. The experimental results have shown significant system capacity improvement compared to the cases using a regular QAM.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Chi Nan   Hu Fangchen  

      摘要 + 此论文可免费阅读 (可能需要登录)

Underwater visible light communication (UVLC) is expected to act as an alternative candidate in next-generation underwater 5G wireless optical communications. To realize high-speed UVLC, the challenge is that the absorption, scattering, turbulence of water medium and the nonlinear response from imperfect optoelectronic devices, which can bring large attenuation and nonlinearity penalty. Nonlinear adaptive filters are commonly used in optical communication to compensate for nonlinearity. In this paper, we compare RLS based Volterra filter, LMS based DP filter and LMS based Volterra filter in terms of performance and computational complexity in underwater visible light communication. We experimentally demonstrate 2.325 Gb/s transmission at a distance of 1.2 m water with a commercial blue LED. Our goal is to assist the readers in refining the motivation, structure, performance and cost of powerful nonlinear adaptive filters in the context of future underwater visible light communication in order to tap into hitherto unexplored applications and services.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Tian Pengfei   Cui Xugao   Chen Honglan   Wang Peiyao   Liu Xiaoyan   Chen Xinwei   Zhou Gufan   Zhang Shuailong   Lu Jie   Qiu Pengjiang   Qian Zeyuan   周 小林   Fang Zhilai   Zheng Lirong   Liu Ran  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this work, a blue gallium nitride (GaN) micro-LED based underwater optical communication (UWOC) system was built, and UWOCs with varied Maalox, chlorophyll and sea salt concentrations were studied. Data transmission performance of the UWOC and the influence of light attenuation were investigated systematically. Maximum data transmission rates at the distance of 2.3 m were 933, 800, 910 and 790 Mbps for experimental conditions with no impurity, 200.48 mg/m3 Maalox, 12.07 mg/m3 chlorophyll and 5kg/m3 sea salt, respectively, much higher than previously reported systems with commercial LEDs. It was found that increasing chlorophyll, Maalox and sea salt concentrations in water resulted in an increase of light attenuation, which led to the performance degradation of the UWOC. Further analysis suggests two light attenuation mechanisms, e.g. absorption by chlorophyll and scattering by Maalox, are responsible for the decrease of maximum data rate and the increase of bit error rate. Based on the absorption and scattering models, excellent fitting to the experimental attenuation coefficient can be achieved and light attenuation by absorption and scattering at different wavelengths was also investigated. We believe this work instructive to apply UWOC for practical applications.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Cossu G.  

      摘要 + 此论文可免费阅读 (可能需要登录)

The growing number of underwater activities is giving momentum to the development of new technologies, such as buoys, Remotely Operated Vehicles (ROVs) and Autonomous Underwater Vehicles (AUVs). The data collected by these vehicles needs to be transmitted to a central unit with high speed. Clearly, wired solution are not suitable, since they strongly impact the mobility. In this scenario, a promising solution is offered by Underwater Optical Wireless Communication (UOWC) technology, which can achieve both high-speed and wireless operation. Here, we provide a comprehensive survey on the challenges, the experimental realizations and the state of the art in UOWC researches.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Xu Jing  

      摘要 + 此论文可免费阅读 (可能需要登录)

Foreseeing the proliferation of underwater vehicles and sensors, underwater wireless optical communication (UWOC) is a key enabler for ocean exploration, with strong competitiveness in short-range bandwidth-intensive applications. We provide a tutorial on the basic concepts and essential features of UWOC as well as an overview of work being conducted in this field. Research challenges, arising from the characteristics of underwater channels, and possible roadmaps are discussed in detail. This review is expected to be of great use to the link designers of this field.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Chen Lian-Kuan   SHAO Yingjie   Deng Rui  

      摘要 + 此论文可免费阅读 (可能需要登录)

We systematically investigate the bubble-induced performance degradation for underwater wireless optical communication (UOWC) with different bubble sizes and positions. By using different transmit and receive diversities, we investigate the effectiveness of spatial diversity on the mitigation of the bubble-induced impairment to the UOWC link. With the help of a 2×2 MIMO using repetition coding (RC) and maximum ratio combining (MRC), a robust 780-Mbit/s UOWC transmission is achieved. The corresponding outage probability can be significantly reduced from 34.6% for the system without diversity to less than 1%.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Xing Fangyuan   Yin Hongxi   Jing Lianyou  

      摘要 + 此论文可免费阅读 (可能需要登录)

This letter investigates the performance of the two-way multi-hop system for underwater optical wireless communications. With the decode-and-forward (DF) relaying, the two-way multi-hop system is modeled, where the effects of absorption, scattering, and oceanic turbulence are all taken into account. An exact closed-form expression for outage probability is derived under the assumption that the oceanic turbulence obeys a log-normal distribution. Numerical results demonstrate the impacts of various parameters on the outage performance and indicate that the two-way multi-hop system significantly improves the performance in comparison to both the one-way multi-hop system and the two-way two-hop system.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Chen Daomin   Wang Jiemei   Li shangbin   Xu Zhengyuan  

      摘要 + 此论文可免费阅读 (可能需要登录)

The received signal intensity fluctuation and communication performance of an underwater optical wireless communication (UOWC) system under the air bubble effects are experimentally investigated. For different bubble density and size, Lognormal, Gamma, Weibull and generalized extreme value distributions are tested to fit the fluctuation of the signal intensity at the receiving end. The best fitting distribution is found to vary with bubble parameters. The communication system performance with OOK and pulse position modulation is further studied.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Guo Haichao   Shan Tao   Li Li   Zhang Li   Li Xiaojun   Gao Han  

      摘要 + 此论文可免费阅读 (可能需要登录)

A sunlight communication system is proposed that uses Sr2Si5N8:Eu2+ phosphors to concentrate sunlight signals in strong background-light noise; thus, a wide spectrum sunlight communication system is converted into a narrow spectrum one. A communication method is proposed to enable compression to the dark line H-α (656.28 nm) spectrum. A 50% solar energy conversion efficiency is achieved, with a 0.3 μs code delay, a 0.2 μs code rise time (20%–80%), and a 96% optical transmittance. Experimental results show that phosphors enhance the sunlight intensity 1.5 times with the same distance. This method has immense potential in future long-distance sunlight communication.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Chen Su   Hu Weixiang   Xu Yang   Cai Yu   Wang Zhiqiang   Zhang Zuxing  

      摘要 + 此论文可免费阅读 (可能需要登录)

Experimental generation of stable mode-locked pulses and cylindrical vector beams (CVBs), from an all few-mode fiber (FMF) ring laser is firstly reported, to the best of our knowledge. In this laser, a section of few-mode erbium-doped fiber (FM-EDF) is used as the gain medium. The FM-EDF is pumped by 976 nm laser light with LP11 mode, which is simultaneously converted and multiplexed through a homemade hybrid device, i.e. wavelength division multiplexing-mode selection coupler (WDM-MSC). All the components in our experiment are connected using FMF. The resulted CVB pulses have a spectral width of 0.33 nm with a repetition rate of 30.58 MHz under the pump power of 340 mW. Moreover, both azimuthally and radially polarized CVBs have been achieved with high purity of >95%. This mode-locked CVB fiber laser with all FMF configuration open the way to manipulate the transverse mode in mode-locked fiber lasers.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Li Chung-Yi   Lu Hai-Han   Huang Yong-Cheng   Huang Qi-Ping   Xie Jing-Yan   Tsai Song-En  

      摘要 + 此论文可免费阅读 (可能需要登录)

A 50 Gb/s four-level pulse amplitude modulation (PAM4) underwater wireless optical communication (UWOC) system across the water–air–water interface is demonstrated in practice. In practical scenarios, laser beam misalignment due to oceanic turbulence degrades performance in UWOC systems. With the adoption of a reflective spatial light modulator (SLM) with electrical controller, not only can the laser be arbitrarily adjusted to attain a water–air–water scenario, but oceanic engineering problems can also be resolved to establish a reliable UWOC link. Brilliant bit error rate performance and clear PAM4 eye diagrams are attained by adopting a Keplerian beam expander and a SLM electrical controller. This proposed PAM4 UWOC system presents a feasible state that outperforms existing UWOC systems due to its feature providing a high-speed water–air–water link.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Shen Chao   Zhao Nanjing   Pribosek Jaka   Ma Mingjun   Fang Li   Huang xingjiu   Zhang Yujun  

      摘要 + 此论文可免费阅读 (可能需要登录)

Spontaneous optical emission properties of laser-produced plasma during laser damage events at input and exit surfaces of fused silica were retrieved and compared. We show that plasma at the input surface is much larger in size and exhibits significantly higher electron number density and excitation temperature even when smaller laser energy was used. This effect was attributed to the stronger laser-plasma coupling at the input surface. In addition, a strong continuum background containing three peaks at 1.3 eV, 1.9 eV and 2.2 eV was observed at the exit surface and possible origins for this effect are also discussed.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Yang Zehua   Han Jing   Wu Wenzhi   Kong Degui   Gao Yachen  

      摘要 + 此论文可免费阅读 (可能需要登录)

The extraordinary optical transmission (EOT) in subwavelength metal structure has been studied widely. Herein, we proposed a strategy for tuning the EOT of bullseye structure. Specifically, the bullseye structure was immersed in a nonlinear medium, and a controlling light was employed to change the refractive index of the medium. At different intensities and distributions of controlling light, the transmission property of signal light in the bullseye structure was simulated. The results show that, a variable transmission spectrum in the bullseye structure can be realized. Moreover, the position of central transmission peak shifts linearly with the increasing intensity of controlling light.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Ma Xiao   Zou Jun   Li Wenhuan   He Jian-Jun  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate a novel type of miniature spectrometer based on a Fourier transform spectrometer (FTS) chip with dense output array and a commercial photodetector (PD) array. The FTS chip has an output array cycle of 20 μm and consists of 51 Mach-Zehnder interferometers (MZIs), the PD array is a commercial linear charged coupled device (CCD). An achromatic triplet lens is used to image the MZI output interferogram onto the CCD with a small aberration. Our experimental result shows that a free spectral range (FSR) from 489 nm to 584 nm and a retrieved spectral resolution of 3.5 nm at 532 nm are obtained. The achieved properties shows that our spectrometer has the potential to outperform the best commercial compact one in terms of most performance indices.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Fardad Shima   Schweisberger Eric   Salandrino Alessandro  

      摘要 + 此论文可免费阅读 (可能需要登录)

In the context of nonlinear plasmonics we review the recently introduced concept of Plasmonic Parametric Resonance (PPR) and discuss potential applications of such phenomenon. PPR arises from the temporal modulation of one or more of the parameters governing the dynamics of a plasmonic system and can lead to the amplification of high-order sub-radiant plasmonic modes. The theory of PPR is reviewed, possible schemes of implementation are proposed, and applications in optical limiting are discussed.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Tian Kangkai   Chu Chunshuang   Che Jiamang   Shao Hua   Kou Jianquan   Zhang Yonghui   Zhang Zi-Hui   Wei Tongbo  

      摘要 + 此论文可免费阅读 (可能需要登录)

The tilted energy band in the multiple quantum wells (MQWs) arising from the polarization effect causes the quantum confined Stark effect (QCSE) for [0001] oriented III-nitride based near ultraviolet light-emitting diodes (NUV LEDs). Here, we prove that the polarization effect in the MQWs for NUV LEDs can be self-screened once the polarization induced bulk charges are employed by using the alloy-gradient InxGa1-xN quantum barriers. The numerical calculations demonstrate that the electric field in the quantum wells becomes weak and thereby flattening the energy band in the quantum wells, which accordingly increases the spatial overlap for the electron-hole wave functions. The polarization self-screening effect is further proven by observing the blue shift for the peak emission wavelength in the calculated and the measured emission spectra. Our results also indicate that for NUV LEDs with a small conduction band offset between the quantum well and the quantum barrier, the electron injection efficiency for the proposed structure becomes low. Therefore, we suggest doping the proposed quantum barrier structures with Mg dopants.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Du Zhengting   Zhang Tianqi   Xie Zhenda   Ning Jian   Lv Xinjie   Xu Jinlong   Zhu Shining  

      摘要 + 此论文可免费阅读 (可能需要登录)

Due to the composition-dependent properties of two-dimensional (2D) transition metal dichalcogenides (TMDs), alloying of existing dissimilar TMDs architecture is a novel and controllable route to tailor crystal structure with superior optical and optoelectronic properties. Here, we reported the hexagonal-phase WSe1.4Te0.6 alloy can enable great promise for enhanced saturable absorption response exceeding the parent component WSe2 and WTe2, with larger modulation depth and lower saturable intensity. These advantages allowed the 1070 nm passively Q-switched lasers based on WSe1.4Te0.6 more efficient, with narrowing pulse duration narrowed to 45%, slope efficiency increased by 232%. Our findings highlighted the appropriate alloying of TMDs as an effective strategy for development of saturable absorbers.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Zhou Tianhua   Ma Jian   Lu Tingting   Hu Guyu   Fan Tingwei   Zhu Xiaopeng   Zhu Xiaolei   Chen Weibiao  

      摘要 + 此论文可免费阅读 (可能需要登录)

One fast simulation method using Markov chains was introduced to simulate angular, energy and temporal characteristics of pulsed laser beam propagation underwater. Angular dispersion of photons with different number of collisions was calculated based on scattering function and state transition matrix of Markov chains. Temporal distribution and energy on the receiving plane were obtained respectively by use of novel successive layering model and receiving ratio. The validity of this method was verified by comparing with Monto Carlo ray tracing (MCRT) method. The simulation results were close to those obtained by MCRT with less time consuming and smoother curves.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Chang Junwei   Zhu Ruihan   Xi Tingting   Xu Mengning   Wang Di   Zhang Lanzhi   Li Dongwei   Hao Zuoqiang  

      摘要 + 此论文可免费阅读 (可能需要登录)

We show the intensity control of filamentation in fused silica by temporally shaping the femtosecond laser pulse. The arbitrary control of filamentation intensity has been obtained by the feedback control based on the genetic algorithm, and the peak intensity of filament has changed from about 670 to around 2100 (CCD counts). This modulation is qualitative agreement with the simulation results. It is shown that the control of the intensity is realized by modulating the peak power of the shaped pulse.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Fan Xiaojun   JIANG J.F.   Zhang Xuezhi   Liu Kun   Wang Shuang   Liu Tiegen  

      摘要 + 此论文可免费阅读 (可能需要登录)

Wake fiber Bragg grating (WFBG) is an ideal quasi-distributed optical fiber sensor. Special attention should be paid to the spectrum and sensing performance of WFBG at extreme temperature due to its poor reflection intensity. In this paper, the temperature characteristics of WFBG from -252.75℃ to 200.94℃ are experimentally investigated. Five WFBGs with reflectivity from ~0.25% to ~10% are used in the experiments. The reflectivity variations and wavelength shifts at different temperatures are studied. Experimental results show that the WFBG can survive and work at extreme temperature, but the performance is affected significantly. The reflectivity is affected significantly by both cryogenic temperature and high temperature. The temperature responses of Bragg wavelengths in the wide temperature range are also obtained.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Gu Zhiyuan   Wang Xianghui   Wang Jianxin   Fan Fei   Chang Shengjiang  

      摘要 + 此论文可免费阅读 (可能需要登录)

Subtractive imaging is used to suppress the axial sidelobes and improve the axial resolution of 4pi microscopy with higher-order radially polarized (RP) Laguerre-Gaussian (LG) beam. A solid-shaped point spread function (PSF) and a doughnut-shaped PSF with a dark spot along the optical axis are generated by tightly focusing higher-order RP-LG beam and modulated circularly polarized beam, respectively. By subtracting the two images obtained with those two different PSFs, the axial sidelobes of the subtracted PSF are reduced from 37% to about 10% of the main lobe and the axial resolution is increased from 0.21λ to 0.15λ.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Zhang Zhike   Li Jinye   Zhao Zeping   Liu Jianguo   Wang Xingjun  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate a package-level passive equalization technology in which the wire bonding-induced resonance effect is used to compensate for the limited gain strength within the Nyquist frequency. The corresponding gain strength under various inductance and capacitance combinations could be quantitatively determined using a numerical simulation. With the increase in the Nyquist frequency, the capacitance shows a greater effect on the gain strength than the inductance. Therefore, the parasitic capacitance should be decreased to realize the desired gain strength at a higher Nyquist frequency. With this equalization technology, a gain strength of 5.8 dB is obtained at 22 GHz, which can compensate for the limited bandwidth for the 112 Gbps PAM4 signal. The experimental results show that 112Gb/s/λ PAM4 transmission based on a directly modulated laser module can be realized with a bit error rate of 1 × 10−3 at a received optical power of 3 dBm.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Xin Tian   Hao Li   Liu Le   Wang Meng   Xi Xiaoming   Wang Zefeng  

      摘要 + 此论文可免费阅读 (可能需要登录)

We report here an ultra-broadband LP01-LP11 mode converter operating at 1 μm based on a long period fiber grating (LPFG) fabricated in a conventional two-mode fiber (TMF) by line-focused CO2 laser. The measured 3 dB-bandwidth is about 240 nm, which is the broadest bandwidth for such fiber mode converters. The maximum conversion efficiency between LP01 and LP11 modes is > 99% over the range of 1000 nm to 1085 nm, almost covering the whole emission band of Yb3+, which is useful for further power scaling of high power fiber lasers operation at 1μm band.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Zhang Zhenzhen   郭 骋   Cui Liang   Zhang Yichi   Du Cheng   Li Xiaoying  

      摘要 + 此论文可免费阅读 (可能需要登录)

Using the few mode erbium doped fiber (FM-EDF) with a simple two-layer erbium doped structure, we demonstrate an all-fiber few mode erbium doped fiber amplifier. The gain equalization among the six spatial modes supported by the FM-EDF is achieved when only the pump in fundamental mode (LP01) is applied. When the signals in six spatial modes are simultaneously amplified, the average modal gain is about 15 dB, and differential modal gain is about 2.5 dB for signal at 1550 nm.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Lin Tianying   Ang Liu   Xiaopei Zhang   Li He   Liping Wang   Hailong Han   Ze Chen   Xiaoping Liu   Haibin Lv  

      摘要 + 此论文可免费阅读 (可能需要登录)

Inspired by recent rapid deep learning development, we present a convolutional-neural-network-based algorithm to predict OAM mode purity in optical fibers using far field patterns. It is found that this image-processing-based technique has an excellent ability in predicting the OAM mode purity, potentially eliminating the need of using bulk optic devices to project light into different polarization states in traditional methods. The excellent performance of our algorithm can be characterized by a prediction accuracy of 99.8% and correlation coefficient of 0.99994. Furthermore, the robustness of this technique against different sizes of testing sets and different phases between different fiber modes are also verified. Hence, such a technique has a great potential in simplifying the measuring process of OAM purity.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Cheng Haijuan   Dong Miao   Tan Qinwen   Meng Linghai   Cai Yi   Jiang Jie   Yang Weisheng   Zhong Haizheng   Wang Lingxue  

      摘要 + 此论文可免费阅读 (可能需要登录)

A gradient-index Reuleaux-triangle-shaped hole array was fabricated on germanium by nanoimprint lithography and inductively coupled plasma processing as a broadband mid-IR antireflective surface. The interaction between the { 111} planes of cubic crystalline Ge and a circular mold successfully produced an orderly and periodically distributed Reuleaux-triangle-shaped hole array. As a result, the average transmittance increased 15.67% over the waveband at 3–12 μm and maintain stable at the incidence angle of up to 60°. The vertices of the Reuleaux triangle showed local enhancement of the electric field intensities due to interference of the incident and reflected radiation fields. It was also found that nonuniform hole depths acted to modulate the transmittance over the 3–12 μm waveband.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Shen Yijiang   Peng Fei   Huang Xiaoyan   Zhang Zhenrong  

      摘要 + 此论文可免费阅读 (可能需要登录)

We develop a source mask co-optimization framework incorporating the minimization of edge placement error (EPE) and process variability band (PV Band) into the cost function to compensate simultaneously for the image distortion and the increasingly pronounced lithographic process conditions. Explicit differentiable functions of the EPE and the PV Band are presented and adaptive gradient methods are applied to break symmetry to escape suboptimial local minima. Dependence on the initial mask conditions is also investigated. Simulation results demonstrate the efficacy of the proposed SMO approach in pattern fidelity improvement, process robustness enhancement and almost unaffected performance with random initial masks.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Huang Xuan   Yang Fang   Song Jian  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this paper, the current research of underwater optical wireless communication (UWOC) network is reviewed first. Hybrid laser diode (LD) and light-emitting diode (LED) based UWOC system is then proposed and investigated, in which a hybrid cluster-based networking with mobility restricted nodes is utilized to improve both the life cycle and throughput of UWOC network. Moreover, the LEDs are utilized for the coarse alignment while the LDs are used for high precision positioning to reduce the difficulty of optical alignment. Finally, challenges and trends for UWOC are pointed out to provide some insight for the potential future work of researchers.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Zheng Qiaoyu   Li Yang   Wu Wenjuan   Zou Jun   Yang Bobo   Shi Mingming  

      摘要 + 此论文可免费阅读 (可能需要登录)

The phosphor in glass (PiG) employing Ce: YAG-doped boro-bismuthate glass via low-temperature co-sintering technology was successfully prepared, using Bi2O3- B2O3-ZnO glass as base material. The photoluminescence (PL) of PiG co-sintered at times ranging from 20 min to 60 min for 700 °C was investigated. As a result, the relative PL intensity of PiG under a reducing atmosphere of CO showed significantly enhanced about 7-14 times than that under air atmosphere sintering for 20-50 min. The photoluminescence intensity decreased gradually with the co-sintering time, which may be due to the corrosion of the YAG lattice structure.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Xu Jianxun   Jiang Ming   Chen Yufa  

      摘要 + 此论文可免费阅读 (可能需要登录)

High-rate techniques, such as optical orthogonal frequency division multiplexing (O-OFDM) and color shift keying (CSK), have been proposed for visible light communication (VLC). To fully exploit their advantages, in this letter we design a modulation scheme called rotated polarity-modulation (RPM) aided complex CSK (CCSK) for O-OFDM based VLC systems, and derive its theoretical bit error rate (BER) and an optimal scaling factor. Analytical and simulation results show that in comparison to the existing schemes, the new RPM-CCSK-OFDM system offers an improved link performance and data rate under a modest complexity. It can also be applied to VLC systems equipped with different types of LED devices, thus enabling flexible deployments.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Zhang Lu   Zhang Wendong   Zhang Shougang   Yan Shu-Bin  

      摘要 + 此论文可免费阅读 (可能需要登录)

Vapor cell provides a well-controlled and stable inner atmosphere for atomic sensors, such as atomic gyroscopes, atomic magnetometers and atomic clocks and its hermeticity affects the stability and aging of atomic sensors. We present the micro-fabrication of a MEMS wafer-level hermit vapor cell based on deep reactive ion etching and vacuum anodic-bonding technology. Anodic bonding process with the voltage increasing in steps of 200 V, had a critical influence on vapor cell hermeticity. Further, the silicon-glass bonding surface was experimentally investigated by SEM, which illustrated that there were no visual cracks and defects in the bonding surface. The leak rate was measured using helium leak detector. The result shows that the vapor cells with different optical cavity lengths comply with the MIL-STD-883E standard (5×10-8 mbar.l/s). Moreover, D2 absorption spectroscopy was characterized via optical-absorption. The bonding strength was determined to be 13 MPa, which further verified the quality of the vapor cells.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Li Yangliang   Shen Chao   Shao Li   Zhang Yujun  

      摘要 + 此论文可免费阅读 (可能需要登录)

Particle ejection is an important process during laser-induced exit surface damage in fused silica. Huge quantity of ejected particles, large ejection velocity and long ejection duration make this phenomenon difficult to be directly observed. An in situ two-frame shadowgraphy system combining with a digital particle recognition algorithm was employed to capture the transient ejecting images and obtain the particle parameters. The experimental system is based on the principle of polarization splitting and can capture two images at each damage event. By combing multiple similar damage events at different time delays, the timeline of ejecting evolution can be obtained. Particle recognition is achieved by an adaptively regularized kernel-based fuzzy C-means algorithm based on grey wolf optimizer. This algorithm overcomes the shortcoming of adaptively regularized kernel-based fuzzy C-means algorithm easily falling into local optimum and can resist strong image noises including diffraction pattern, laser speckle and motion artifact. This system is able to capture particles ejected after 600 ns with a time resolution of 6 ns and spatial resolution better than 5 μm under the particle recognition accuracy of 100%.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

He Qiang   Wang fan   Lin Zhiquan   Shao Chongyun   Wang Meng   Wang Shikai   Yu Chunlei   Hu Lili  

      摘要 + 此论文可免费阅读 (可能需要登录)

Using a heavily erbium doped aluminosilicate fiber prepared by sol-gel method combined with high temperature sintering, the temperature dependence of spectrum around 1.55nm band and single mode fiber laser properties were investigated respectively. The absorption cross section increases 29.2% at ~1558nm with temperature increasing from 20℃ to 140℃, while the emission cross section increase 4.3% slight. In addition, the laser slope of the EDF at 1558nm decreases 4.4% from 10.8% to 6.4 with the temperature increasing from 18℃ to 440℃. Meanwhile, an experiment lasting 3 hours proves that the fiber laser has excellent stability below 440℃.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Qian Jinwang   Zheng Zhennan   Lei Mingzheng   Song Chunqi   huang shanguo   Gao Xinlu  

      摘要 + 此论文可免费阅读 (可能需要登录)

A complex-coefficient microwave photonic filter with continuous tunability is proposed and demonstrated, which has a compact structure and stable performance without splitting the optical path and tuning the polarization state. By only controlling the DC biases of the modulator, the amplitudes and the phases of the filter taps can both be tuned. The phase difference between the two filter taps covers a full 360° range from 10 GHz to 32 GHz. Frequency responses of the proposed filter are measured within 10-20 GHz with different center frequency.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Srivastava Vibhu   Mishra Prateek   Sunny Sunny  

      摘要 + 此论文可免费阅读 (可能需要登录)

The impulse response for a phase-change material Ge2Sb2Te5 (GST) based photodetector integrated with SOI waveguide is simulated using finite difference time domain. The current is calculated by solving the drift-diffusion model for a short pulse (~10 fs) excitation for both of the stable phases. FWHM values of less than 1 ps are found in the investigation. The crystalline-GST has higher 3dB BW than the amorphous-GST at 1550 nm wavelength with responsivities of 21 A/W and 18.5 A/W, respectively, for 150nm thick GST layer biased at 2 V. Broad spectrum can be utilized by tuning the device using phase-change property of material in the near infra-red region.

       PDF全文        Chinese Optics Letters ，2019年第17卷第10期 pp.10      

Wang Fang   Deng Xuewei   Liquan Wang   Li Fuquan   Han Wei   Zhou Wei   Huang Xiaoxia   Huaiwen Guo   Qihua Zhu  

      摘要 + 此论文可免费阅读 (可能需要登录)

Fifth harmonic generation (5th HG) of Nd: glass laser is an effective way to acquire high-energy coherent deep-ultraviolet radiation near 200 nm. In this work, cascade generation of the fifth harmonic of Nd: glass laser in a 5mm ADP crystal was investigated, and maximum conversion efficiency of 14% and large angular acceptance of 45 mrad were demonstrated at non-critical phase-matching temperature of -75.1℃. However, as the results reveal, the temperature sensitivity and nonlinear absorption would hinder its high-energy application. As for it, based on the complementary relationship of angular and temperature in the phase-matching condition, an upgraded focusing 5thHG design coupled with cylindrical temperature distribution scheme was proposed. By this upgraded focusing design, more than the improving of the conversion efficiency, the output 5ω near-field intensity distribution turns to be insensitive to the temperature gradient. Potentially, this idea can be applied for many other frequency conversion schemes such as high-repetition frequency lasers which have similar temperature gradient problems.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

kang minqiang   Deng Ying   Yan xiongwei   Zeng Xiaoming   Guo Yangwu   Yao Jiyong   Zeng Fa   ZHENG Jiangang   Zhou Kainan   Qu Chongbing   Su Jingqin   Zhu Qihua  

      摘要 + 此论文可免费阅读 (可能需要登录)

We report an efficient mid-infrared extracavity optical parametric oscillator (OPO) based on the nonlinear crystal BaGa4Se7 pumped by a diode-side-pumped Q-switched Nd:YAG laser. The maximum pulse energy of 1.03 mJ at 4.25 μm is obtained with the repetition rate of 10 Hz and pulse width of 12.6 ns when the pump energy was 13.5 mJ, corresponding to an optical-to-optical conversion efficiency of 7.6% from 1.064μm to 4.25 μm. And the idler wave slope convertion efficency was 12%. To our best knowledge, it is the highest reported conversion efficiency for the compact BaGa4Se7 OPO driven by the Nd:YAG laser.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Wang Zhou-Xiang   Xie Yu-Chen   Huang Shuang-Yin   Zhou Han   Liu Rui   Liu Zhi-Feng   Wang Min   Qi Wen-Rong   Tian Qian-Qian   Kong Ling-Jun   Tu Chenghou   Li Yongnan   Wang Huitian  

      摘要 + 此论文可免费阅读 (可能需要登录)

In free-space or in optical fibers, the orbital angular momentum (OAM) multiplexing for information transmission has been greatly developed. The light sources used were well coherent communication bands and the fibers used were customized. Here we use an 810-nm femtosecond laser to generate optical vortices carrying OAM, and then feed them into two kinds of commercial step-index few-mode fibers to explore the transmission characteristics of OAM modes. We also propose a method without multiple-input multiple-output digital signal processing to identify the input OAMs. It is of great guiding significance for high-dimensional quantum information experiments via the OAMs as a degree of freedom, using the light generated by the spontaneous parametric down-conversion as source and the commercial fibers for information transmission.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Gu Fuxing   ubaid saima   Liao Feng   Tao Guo   Qi Zhao   Linghu Shuangyi   Ma Yanna   Yu Jiaxin  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate an effective approach of mode suppression by simply using a tungsten probe to destroy the external neck surface of polymer microbottle resonators. The higher-order bottle modes with large axial orders, spatially located around the neck surface of the microresonator, will suffer large optical losses. Thus, excitation just with an ordinary free-space light beam will ensure direct generation of single fundamental bottle mode lasers. This method is very low cost and convenient, and can obtain high side mode suppression factors. Our work demonstrated here may have promising applications such as lasing and sensing devices.

       PDF全文        Chinese Optics Letters ，2019年第17卷第12期 pp.12      

Cui Yuan   Zheng Guoxing   Chen Ming   Zhang Yilun   Yang Yan   Tao Jin   Li Zile  

      摘要 + 此论文可免费阅读 (可能需要登录)

Design of a conventional zoom lens is always challengeable because it requires not only sophisticated optical design strategy, but also complex and precise mechanical structures for lens adjustment. Here, we propose a continuous-zoom lens consisting of two chiral geometric metasurfaces with dielectric nanobrick arrays sitting on a transparent substrate. The metalens can continuously vary the focal length by rotating either of the two metasurfaces along its optical axis without changing any other conditions. Because of the polarization dependence of the geometric metasurface, the positive and negative polarities are interchangeable in one identical metalens only by changing the handedness of the incident circularly polarized light, which can generate varying focal lengths ranging from −∞ to +∞ in principle.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Dong Jia-ning   Fan Jie   Mao Si-da   Lan Yun-ping   Zou Yonggang   Wang Hai-zhu   Zhang Jia-bin   Ma Xiaohui  

      摘要 + 此论文可免费阅读 (可能需要登录)

The effect of thermal annealing on the optical properties, microstructure and laser-induced damage threshold (LIDT) of HfO2/Ta2O5/SiO2 HR films have been investigated. The transmission spectra shift to short wavelength and the x-ray diffraction (XRD) diffraction peaks of monoclinic structure HfO2 are enhanced after thermal annealing. The calculated results of m(-111) diffraction peak show that HfO2 grain size is increased, which is conducive to increasing the thermal conductivity. The thermal annealing also reduces the laser absorption of HR films. The improvement of thermal conductivity and the decrease of laser absorption both contribute to the improvement of LIDT. The experimental results show that the highest LIDT of 22.4J/cm2 is obtained at 300℃ annealing temperature. With the further increase of annealing temperature, the damage mechanism of the film changes from thermal stress damage to thermal explosion damage, resulting in the decrease of LIDT

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Li Xiang   wang xiaodan   Ma Hai   Chen Feifei   Zeng Xionghui  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this work, Er doped AlN, Pr doped AlN, and Er, Pr co-doped AlN thin films were prepared by ion implantation. After annealing, the luminescence properties were investigated by cathodoluminescence. Some new and interesting phenomena were observed. The peak at 480 nm was observed only for Er doped AlN. However, for Er, Pr co-doped AlN, it disappeared. At the same time, a new peak at 494 nm was observed, although it was not observed for Er-doped AlN or Pr-doped AlN before. Therefore, the energy transfer mechanism between Er3+ and Pr3+ in AlN thin films were investigated in detail. Through optimizing the dose ratio of Er3+ with respect to Pr3+, white light emission with CIE chromaticity coordinate (0.332, 0.332) was obtained. This work may provide a new strategy for realizing white light emission based on nitride semiconductors.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Fang Fang   Sun Bing   Zhang Zuxing   Xu Jing   Zhang Lin  

      摘要 + 此论文可免费阅读 (可能需要登录)

The spectral characteristics and sensitivities of a tapered two-mode fiber (TTMF) sandwiched between two single-mode fibers (SMFs) are systematically proposed. Theoretical calculations reveal that a dispersion turning point (DTP) appears when the group effective refractive index (RI) difference between the fundamental mode and the higher-order mode equals zero, as a result, ultrahigh RI sensitivities can be achieved. Furthermore, the location of the DTP is strongly dependent on the tapering condition. Then we experimentally demonstrate high sensitivities of the RI sensor with the waist diameter of 2.4 μm by means of immersing it in a flow cell filled with glycerol solution. Further tracking the resonant wavelength shift around the DTP it is found that the proposed RI sensor exhibits a sensitivity of 1.81×104 nm/RIU and a limits of detection down up to 3.29×10-5 RIU in glycerol solution.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Wang Mingjun   Feng Shaodong   Wu Jigang  

      摘要 + 此论文可免费阅读 (可能需要登录)

We propose a resolution enhancement method for lensless in-line holographic microscope (LIHM) by combining the hologram segmentation and pixel super-resolution (PSR) techniques. Our method is suitable for imaging specific target object in samples where the in-line hologram is disturbed by other objects in the samples. The resolution-enhancement capability of our method was proved by numerical simulations and imaging experiments while using a standard resolution target in a two-layer setup. We also applied our LIHM system to image the sample of living algae Euglena gracilis in water solution for further demonstration.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Ma Qungang   Cao Liangcai   He Zehao   Zhang Shengdong  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this paper, the principle and the optical methods for light-field display are introduced. The light-field display is divided into three categories, including layer-based method, projector-based method, and integral imaging method. The principle, characteristic, history and advanced research results of each method are also reviewed. The advantages of light-field display are discussed by comparing with other display technologies including binocular stereoscopic display, volumetric 3D display and holographic display.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Liu xin   Lei Ruoshan   Huang feifei   Deng Degang   Wang Huanping   Zhao shilong   Xu Shiqing  

      摘要 + 此论文可免费阅读 (可能需要登录)

BaMoO4: Ho3+/Yb3+ phosphors with different concentrations were fabricated by a gel combustion method. The upconversion (UC) luminescence, intrinsic optical bistability (IOB) and the corresponding mechanisms were reported for the present system. The optical thermometric properties based on the red (5F5 →5I8) and green (5F4/5S2 →5I8) emissions were studied. The sensing sensitivities could be tuned by manipulating the cooperative energy transfer (CET) process. The highest absolute sensitivity was 99 ×10-4 K-1 at 573 K, which was larger than many previous UC materials.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Othman Nurulanati   Tay Kim Gaik   Mohd Shah Nor Shahida   Talib Rahmat   Pakarzadeh Hassan   Cholan Noran Azizan  

      摘要 + 此论文可免费阅读 (可能需要登录)

The influence of the fourth-order dispersion coefficient on behavior of parametric gain and saturation power of one-pump fiber optical parametric amplifier over a signal wavelength span in presence of fiber random dispersion fluctuations was investigated. The output signal power for the parametric gain calculation was obtained by numerically solving the three-coupled amplitude equations. Based on the calculations of the parametric gain over a variation of the signal wavelength, it is found that the saturation power behavior is dependent on the behavior of parametric gain. The manipulations of signal wavelength and fourth-order dispersion coefficient changed the phase-matching condition, thereby affecting the resulting parametric gain and saturation power.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Guo Ying   Wang Kangshuai   Jiang Xueqin   Huang Duan  

      摘要 + 此论文可免费阅读 (可能需要登录)

Seeking for good error correcting codes to improve the efficiency of continuous-variable quantum key distribution (CVQKD) reconciliation is a concerned issue. Due to the introduction of multidimensional reconciliation, the error correcting techniques in the classical binary-input additive white gaussian noise (BI)-AWGN channel is applicable to CVQKD. In this letter, we apply the quasi-cyclic low-density paritycheck (QC-LDPC) codes, which are specified in 5G protocol, to the reconciliation process. Simulation results show that the reconciliation efficiency can reach 92.6% when the code rate is 22/68 and the signal-to-noise ratio (SNR) is 0.623. Such a new error correcting code points out a new direction for the development of CVQKD.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Gao Qian   Zhang Hengli   Javed Fayyaz  

      摘要 + 此论文可免费阅读 (可能需要登录)

A laser diode partially end-pumped, electro-optic Q-switched, Yb:YAG slab laser was reported. We obtained an output energy of 14.6 mJ/pulse with a pulse width of 30 ns at a repetition frequency of 2 kHz, and the corresponding peak power was 480 kW. The beam quality factors M2 in the unstable direction and the stable direction were 1.32 and 1.25, respectively.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Wang Qiangguo   Cui Na   Yao Yongping   Meng Lihua   Li Lei   Dong Lulu   Zhang Huiyun   Liu Shande   Li Dehua  

      摘要 + 此论文可免费阅读 (可能需要登录)

With a Nd:ScYSiO₅ crystal, a high peak power electro-optically Q-switched 1.0 μm laser and tri-wavelength laser operations at 1.3 μm band are both investigated. With RTP electro-optical switcher and a polarization beam splitter, a high signal-to-noise ratio 1.0 μm laser is obtained, generating the shortest pulse width of 30 ns, the highest pulse energy of 0.75 mJ, and the maximum peak power of 25.5 kW, respectively. The laser mode at the highest laser energy level is TEM₀₀ mode with the M² value in X and Y directions to be M_x²=1.52 and M_y²=1.54. Besides, a tri-wavelength Nd:ScYSiO₅ crystal laser at 1.3 μm is also investigated. A maximum tri-wavelength output power is 1.03 W under the absorbed pump power of 7 W, corresponding to a slope efficiency of 14.8%. The properties of the output wavelength are fully studied under different absorbed pump power.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

刘 贺言   Yu yongji   sun dehui   Liu Hong   Wang yuheng   Zheng hao   Li dan   Jin Guangyong  

      摘要 + 此论文可免费阅读 (可能需要登录)

We report on a 1514nm eye-safe passively Q-switched self-optical parametric oscillator (SOPO). The nonlinear crystal is a a-cut Nd:MgO:PPLN crystal and the size of the crystal was 6 mm × 2 mm ×30 mm with 0.4at.% Nd3+ doped, grating period was 29.8μm.When the crystal absorbed 12.8W, the output maximum single pulse energy reached 39μJ and the pulse width of 6.1ns at a 5.4 kHz repetition rate was obtained, peak power is 6kw and giving a slope efficiency of 42%.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Wei Wei   Huang Lihua   zhu Xinran   ling liqing   Guo Kai   Huang Huijie  

      摘要 + 此论文可免费阅读 (可能需要登录)

In our paper two kinds of handwriting traces, colored and colorless, are studied by means of Reflectance Transformation Imaging (RTI).The illumination direction and rendering mode can be changed alternatively to obtain two-dimensional and three-dimensional details of the traces that are not viewed easily by the naked eye. Furthemore, an objective evaluation method without reference is applied to evaluate the reconstructed images, which provides a basis for setting the illumination direction and rendering mode. Therefore, the information of handwriting traces including the written content, the writing features, and the stroke order features can be obtained objectively and accurately.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Wang Xiaoyan   Yan Xiaona   Jin Kailong   Dai Ye   Jin Zuanming   Yang Xihua   Ma Guohong  

      摘要 + 此论文可免费阅读 (可能需要登录)

Based on Kogelnik’s coupled-wave theory, it is found that when a femtosecond pulse incidents on transmitted volume holographic grating, two transverse standing waves along grating vector direction will be generated inside the VHG. Due to field localization of two standing waves, they have two different velocities along propagation depth. On the output plane of the VHG, femtosecond dual pulses are generated on both the diffracted and transmitted directions. Results show that the pulse interval is determined by the refractive index modulation and thickness of the grating, while the waveform of the dual pulses is independent of grating parameters.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Cai Yuancheng   Gao Xiang   Ling Yun   Xu Bo   Qiu Kun  

      摘要 + 此论文可免费阅读 (可能需要登录)

A pre-coding-assisted power detection scheme for radio over fiber downlink is presented. This scheme can eliminate laser phase noise, while avoiding high energy-consuming electrical carrier required in conventional power and/or envelope detection scheme. Theoretical analysis and experimental verification are performed. 0.625 Gbaud pre-coded quadrature phase shift keying or 16 quadrature amplitude modulation signals can both be recovered by power detec-tion without electrical carrier assistance at the receiver after 75 km fiber transmission. Not only robust against the laser phase noise, an improvement of about 5 dB in receiver sensitivity can also be achieved, as compared with the conventional power detection scheme.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Xiong Ling   Qi Erhui   Luo Xiao   Zhang Feng   Xue Donglin   Zhang Xuejun  

      摘要 + 此论文可免费阅读 (可能需要登录)

We implemented a stitching swing arm profilometer (SSAP) test for inner and outer region of a large aspheric surface with a short arm. The SSAP was more capable of improving sampling density of surface, and was less sensitive to system error, like vibration noise, air-table noise. Firstly, a calculation model was built to evaluate the sampling density of the SSAP test. Then sensitivity to system noise was tested when different length of arm was used. At the end, an experiment on a 3m diameter aspheric was implemented, where test efficiency was promoted and high sampling density was achieved.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Wang Huan   Guo Lu   Wu Zhao   Chen Guangcan   Lu Dan   Zhao Lingjuan  

      摘要 + 此论文可免费阅读 (可能需要登录)

We report a distributed-Bragg-reflectors-based 4 × 40 GHz mode-locked laser diode (MLLD) array monolithically integrated with an MMI combiner. The laser produces 2.98-ps pulses with a time-bandwidth product of 0.39. The peak wavelength of the MLLD array can be tuned by 8.4 nm while maintaining a good mode-locked state. The four mode-locked channels could work simultaneously with the peak wavelength interval around 3 nm.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Wang Mengyu   Yang Yu   Meng Lingjun   Jin Xueying   Dong Yongchao   Zhang Lei   Xu Wenbin   Wang Keyi  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this paper, we demonstrate high-Q, millimeter-size, and V-shaped calcium fluoride crystalline resonators for modal modification. To manufacture such resonators, we develop a home-made machining system and explore a detailed process. With a dedicated polished container, three special polishing steps, including grinding, smoothing, and polishing, are employed to achieve the required surface smoothness, which is characterized by less than 3 nm. An ultra-high Q-factor exceed 108 is obtained by a coupled tapered fiber. In addition, a customized packaged structure for our disk resonator is achieved. The Q maintenance and stable spectrum are realized by sealing the coupling system in a hard disk. The simple, stable, portable, controlled and integratable device would provide great potential in optical filters, sensors, nonlinear optics, cavity quantum electrodynamics and especially some applications that require large resonators such as gyroscopes.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

Cai Hao   Yu Xingtao   Chu Qian   Jin Zhiqiang   Lin Bo   Wang Guanghui  

      摘要 + 此论文可免费阅读 (可能需要登录)

A metal-lined hollow-core fiber based Raman probe extension kit is proposed in this paper for in Situ and sensitive ultramicro-analysis. Hollow-core fiber can confine light and fluid sample in its hollow core, with enhanced light-sample interaction. By using a homemade light coupling device with a glass window for liquid isolation, a 3.5 cm-long hollow-core fiber could mount on and connect to a Raman probe, with perfect light coupling efficient. After full filling the hollow-core fiber chamber with volume of 13 µL by using a syringe pump, it can act as an extension kit for ordinary Raman probe and could be used as ultramicro-analysis tool for the sample of microfluidic chips. In order to enhance its sensitivity, a gold film coated fiber tip is inserted into the capillary, which can double the Raman signal received by reflecting pump light and Raman light. Finally, a good sensitivity of detection limit of 5% for ethanol solution and an enhancement factor of 2 comparing with direct detection of bulk sample volume are demonstrated. Above all, our device can be utilized as a Raman probe extension kit, which is suitable for rapid, sensitive and in Situ measurements for few µL sample.

       PDF全文        Chinese Optics Letters ，2019年第17卷第11期 pp.11      

huang wei   cui yulong   Zhou Zhiyue   Li zhixian   Chen Yubin   Wang Zefeng  

      摘要 + 此论文可免费阅读 (可能需要登录)

We report here a diode-pumped pulsed mid-infrared laser source based on gas-filled hollow-core fibers (HCFs) towards all-fiber structure by tapering method. The pump laser is coupled into an acetylene-filled HCF through a tapered single-mode fiber. By precisely tuning the wavelength of the diode to match different absorption lines of acetylene near 1.5 μm, mid-infrared emission around 3.1~3.2 μm is generated. With 2 m HCFs and 3 mbar acetylene gas, a maximum average power of 130 mW is obtained with a laser slope efficiency of ~24%. This work provides a potential scheme for all-fiber mid-infrared fiber gas lasers.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Lu Zhiyong   Lu Wei   Zhou Yu   Sun Jianfeng   Xu Qian   wang lijuan  

      摘要 + 此论文可免费阅读 (可能需要登录)

A scanning three-dimensional coherent ladar based on the frequency modulated continuous wave (FMCW) is proposed and demonstrated, which can obtain many three-dimensional high-quality images. The system utilizes an electro-optic modulator and an optical filter to output a linear frequency modulated continuous waveform with a bandwidth of 2GHz. The flexible and variable rotating double prism is used for beam scanning. The images of flight demonstration are formed by attitude compensation correction. The experiment result validates the performance of our system for airborne three-dimensional scanning imaging.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Zhang Li   Lin Fei   qiu xiaodong   Chen Lixiang  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate the full vectorial feature of second-harmonic generation (SHG), i.e., from infrared full Poincaré beams to visible full Poincaré beams, based on two cascading type-I phase-matching BBO crystals of orthogonal optical axes. We visualize the structured features of vectorial SHG wave by using Stokes polarimetry and show the interesting doubling effect of polarization topological index, i.e., a low-order full Poincaré beam is converted to a high-order one. However, the polarization singularities of both C-points and L-lines are found to keep invariant during the SHG process. Our scheme could offer a deeper understanding on the interaction of vectorial light fields with media and can be generalized to other nonlinear optical effects

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

zhou xiong   Wang Hui   Xia Haiping   Song Hongwei   Chen Xu   Hu jianxu   chen baojiu  

      摘要 + 此论文可免费阅读 (可能需要登录)

Yb³⁺/Er³⁺ co-doped Na₅Lu₉F₃₂ single crystals used as a spectral upconverter to improve the power conversion efficiency of perovskite solar cells are prepared via an improved Bridgman approach. Green and red upconversion (UC) emissions under the excitation of near-infrared (NIR) bands of 900-1000 nm and 1400-1600 nm can be observed. The effectiveness of the prepared materials as spectral converter is verified by the enhancement of power conversion efficiency of perovskite solar cells. Sample with UC layer is 15.5% more efficient to convert sunlight to electricity comparing to the UC layer-free sample due to the absorption of sunlight in the NIR range. The results suggest the synthesized Yb³⁺/Er³⁺ co-doped Na₅Lu₉F₃₂ single crystals are suitable for enhancing the performance of perovskite solar cells.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Zhang Xiaotong   Yang Shitai   Yuan Libo  

      摘要 + 此论文可免费阅读 (可能需要登录)

By using a specialty designed optical fiber, a series of powerful microparticle manipulation tools including optical tweezers, a micro-optical hand and an optical gun are developed and demonstrated. In this paper, a review of our research activities on the optical manipulation of microparticles will be presented. In particular, we will describe a kind of specialty optical fiber designed and fabricated for building optical trapping and manipulating tools. The performance of annular core fiber based optical tweezers, a multicore, fiber-based micro-optical hand and a coaxial dual waveguide fiber-based optical gun are demonstrated as examples of applications and discussed in detail. The fiber can be used in cell manipulation in life science and drug response in medicine.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Yang Xin   Wei Shibiao   Kou Shanshan   Yuan Fei   Cheng En  

      摘要 + 此论文可免费阅读 (可能需要登录)

The misalignment of optical vortex (OV) beams, including transversal displacement and tilt, occurs in many situations, including on reflection or refraction at an interface between two different media and in propagation and tracking systems for optical communications. We propose a reliable method to determine and subsequently eliminate tilt and transversal displacement in an OV beam. An experimental setup was established to verify the proposed method and the experimental results showed good agreement with those of the numerical simulations. Using the measured misalignments, the initial orbital angular momentum spectrum can be recovered in free space.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Miao Shuaijie   Zhang Wentao   Song Ying  

      摘要 + 此论文可免费阅读 (可能需要登录)

A new structure of short-cavity random fiber laser (RFL) with narrow linewidth lasing is proposed. A π-phase-shifted fiber Bragg grating (π-FBG) loop mirror was used in the RFL to spectral filtering and suppress multi-mode oscillation due to the narrow transmission window. The random feedback of the RFL was implemented by a randomly dispersed weak reflection FBG array. The high gain of the erbium-doped fiber and a half-open cavity design result in a low lasing threshold. The linewidth of the laser was 225 Hz with 58 dB side-mode-suppression-ratio. The laser threshold was 4.5 mW and the optical signal-to-noise ratio was up to 63 dB.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Liu Zhentao   Shen Xia   Liu Honglin   Yu Hong   Han Shensheng  

      摘要 + 此论文可免费阅读 (可能需要登录)

The resolution of a conventional imaging system based on first-order field correlation can be directly obtained from the optical transfer function. However, it is challenging to determine the resolution of an imaging system through random media, including imaging through scattering media and imaging through randomly inhomogeneous media, since the point-to-point correspondence between the object and the image plane in these systems cannot be established by the first-order field correlation anymore. In this paper, from the perspective of ghost imaging, we demonstrate for the first time to our knowledge that the point-to-point correspondence in these imaging systems can be quantitatively recovered from the second-order correlation of light fields, and the imaging capability, such as resolution, of such imaging schemes can thus be derived by analyzing second-order correlation of the optical transfer function. Based on this theoretical analysis, we propose a lensless Wiener-Khinchin telescope based on second-order spatial autocorrelation of thermal light, which can acquire the image of an object by a snapshot via using a spatial random phase modulator. As an incoherent imaging approach illuminated by thermal light, lensless Wiener-Khinchin telescope can be applied in many fields such as X-ray astronomical observations.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Liu Xinyang   Li Xiaowen   Zhao Shengzhi   Yang Kejian   Guo Lei   Li Tao   Qiao Wenchao   Li Ming   Zhang Baitao   He Jingliang   Zheng Lihe   Su Liangbi   Xu Jun  

      摘要 + 此论文可免费阅读 (可能需要登录)

A dual-wavelength synchronously mode-locked homogeneously broadened bulk laser operating at 1985.6 nm and 1989 nm is presented for the first time, to the best of our knowledge, which delivers a maximum output power of 166 mW and a repetition rate of 85 MHz. The pulse duration was measured to be 16.8 ps by assuming a Sech2 pulse shape. The recorded autocorrelation trace showed frequency beating signals with an interval of 3.8 ps and a FWHM duration of 2 ps, corresponding to an ultrahigh beating frequency of about 0.26 THz, which agrees well with the frequency difference of the emitted two spectral peaks. The results indicated that such a kind of dual-wavelength mode-locked Tm:YAP laser could be potentially used for generating terahertz radiations.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Chen Zhidong   Sang Xinzhu   Li Hui   Wang Yuan   Zhao Linmin  

      摘要 + 此论文可免费阅读 (可能需要登录)

A novel see-through virtual retina display (VRD) system is proposed in this letter. An optical fiber projector is used as the thin-light-beam source, which is modified from a laser scan projector by separating the laser sources and the scan mechanical structure. A synthetic aperture method is proposed for simple, low-cost fabrication of a volume holographic lens with large numerical aperture. These two key performance-enhanced elements are integrated into a lightweight and ordinary-glasses-like optical see-through VRD system. The proposed VRD system achieves a weight of 30 grams and a diagonal field of view of 60.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Li Yuepeng   Cai Yawen   Li Runmin   Shi Haosen   Tian Haochen   He Mingzhao   Song Youjian   Hu Minglie  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate a robust femtosecond LIDAR setup by using two free running environmentally stable all polarization-maintaining (PM) nonlinear amplified loop mirror mode-locked fiber lasers. Based on asynchronous optical sampling (ASOPS) method, a ranging accuracy of ±2 μm within 65m has been achieved, as tested in an 80-meter long underground optical tunnel. Through Kalman filter in the real-time data processing, the measurement accuracy can be maintained at a 200 Hz update rate. This setup provides a practical tool for various large scale industrial and astronomical ranging applications.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Gan Haiyong   He Yingwei   Liu Xiangliang   Xu Nan   Wu Houping   Feng Guojin   Liu Wende   Lin Yandong  

      摘要 + 此论文可免费阅读 (可能需要登录)

An absolute cryogenic radiometer (ACR) with a detachable optical window was designed and built for high accuracy optical radiant power measurement and photodetector spectral responsivity calibration. The ACR receiver is an electroplated pure copper cavity with a 50-μm-thick wall and inner surface coated with a specular black polymer material mixed with highly dispersible carbon nanotubes. The absorptivity of the cavity receivers was evaluated to be ≥0.9999 in 250 nm ~16 μm wavelength range and ≥0.99995 in 500 nm ~16 μm. The cavity receiver works at the temperature of ~5.2 K with nW-level noise-equivalent-power. The relative standard uncertainty is 0.041% for the measurement of ~100 μW optical radiant power (250 nm ~ 16 μm) and 0.015% for ~1 mW (500 nm ~ 16 μm).

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Deng Yuting   Jin Guofan   Zhu Jun  

      摘要 + 此论文可免费阅读 (可能需要登录)

Freeform surfaces are difficult to manufacture due to their lack of rotational symmetry. To reduce the requirements for manufacturing precision, a design method is proposed for freeform reflective-imaging systems with low surface-figure-error sensitivity. The method considers both the surface-figure-error sensitivity and optical specifications, which can design initial systems insensitive to surface figure errors. Design starts with an initial planar system; the surface-figure-error sensitivity of the system is reduced during the construction. The proposed method and another which is irrelevant to figure-error sensitivity are used to design a freeform off-axis three-mirror imaging system. Comparison of the sensitivities of the two systems indicates the superiority of our proposed method.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Wang Xin   Yang Sihua  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this study, the feasibility of visualization of human joints using photoacoustic tomography (PAT) is investigated. To verify this idea, the system of integrated optical fiber bundles and custom-made flexible transducer is established, both of which give the advantage of morphological adaptation, therefore, the coupling section can be worn on human limbs. The imaging capacity of the flexible-transducer-based PAT system is validated by mapping the structures of the finger and the wrist joint. To our knowledge, it is the first time to achieve photoacoustic imaging of such a large human wrist joints. The cross-sectional photoacoustic images of a healthy joint clearly exhibit main internal structures including phalanx, tendons and blood vessels, which are comparable with the corresponding 3.0 T MRI images. The experimental results demonstrate that the proposed system holds promise for early diagnosis of joint disorders.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Zhou Xingye   Tan Xin   Wang Yuangang   Song Xubo   Han Tingting   Li Jia   Lu Weili   Gu Guodong   Liang Shixiong   Lv Yuanjie   Feng Zhihong  

      摘要 + 此论文可免费阅读 (可能需要登录)

Ultroviolet (UV) detectors with large photosensitive area are more advantageous in low-level UV detection applications. In this letter, high-performance 4H-SiC p-i-n avalanche photodiodes (APDs) with large active area (800 µm diameter) are reported. With the optimized epitaxial structure and device fabrication process, a high multiplication gain of 1.4×10⁶ is obtained for the devices at room temperature, and the dark current is as low as ~10 pA at low reverse voltages. In addition, a record external quantum efficiency (QE) of 85.5% @ 274 nm is achieved, which is the highest value for the reported SiC APDs. Furthermore, the rejection ratio of UV to visible light reaches about 10⁴. The excellent performance of our devices indicates a tremendous improvement for large-area SiC APD-based UV detectors. Finally, the UV imaging performance of our fabricated 4H-SiC p-i-n APDs is also demonstrated for system-level applications.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Zhang Kui   Wang Zhengwei   Chen Guodong   Wang Yang   zeng Aijun   Zhu Jing   Avakaw Syarhei   Tsikhanchuk Heorgi  

      摘要 + 此论文可免费阅读 (可能需要登录)

A Te-free binary phase change material SbBi is used as a new inorganic photoresist for laser heat-mode lithography. It shows good film-forming ability, low threshold power for crystallization, and enough etching selectivity. Line-type, dot-type, and complex pattern structures with the smallest feature size of 275 nm are fabricated on SbBi thin films using a laser direct writing system. In addition, the excellent grating structures with a period of 0.8 m demonstrate that thermal interference does not affect the adjacent microstructures obviously. These results indicate that SbBi is a promising laser heat-mode resist material for micro/nanostructure fabrication.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Luo Xiaoqing   Tan Zhi-Yong   Wang Chang   Cao Juncheng  

      摘要 + 此论文可免费阅读 (可能需要登录)

We propose and experimentally demonstrate a wideband linear polarization converter in reflection mode operating from 2.4 to 4.2 THz with conversion efficiency more than 80%. Our device can expand the applications to a higher frequency band. A numerical simulation was performed for this metamaterial converter, which showed a good agreement with experimental results. Importantly, a concise and intuitive calculating model is proposed for the Fabry-Pérot cavity. The theoretical results indicate that the underlying reason for the enhanced polarization conversion is the additional phase difference induced by the resonance of meta-structure and multiple reflections within the Fabry-Pérot cavity.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Yang Baodong   Zhang Jinfang   Wang Junmin  

      摘要 + 此论文可免费阅读 (可能需要登录)

An experimental investigation of two-color polarization spectroscopy (TCPS) is presented based on the cesium 6S1/2 - 6P3/2 - 8S1/2 (852.3 nm + 794.6 nm) ladder-type system in a room-temperature vapor cell. The dependency of lineshapes of TCPS on the power of 852.3 nm pump and 794.6 nm probe laser are measured in detail, and we confirm that the linewidth of TCPS in counter-propagating configuration between the pump and probe laser beams is obviously narrower than that of co-propagating configuration due to atomic coherence effect. It is helpful for laser stabilization to excited state transition using TCPS without frequency modulation.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Xie Youpeng   Lei Ting   Yang Chuanwu   Du Luping   Yuan Xiao-Cong (Larry)  

      摘要 + 此论文可免费阅读 (可能需要登录)

Digital micro-mirror device (DMD)-based optical switch has the advantages of high-speed channels reallocation, miniaturization, stability and large capacity for short reach optical communication in Datacenter. However, the thermal turbulent atmosphere in Datacenter would cause perturbations and channel crosstalk for the optical switch. The self-healing optical beams such as the Bessel beams have the non-diffraction property to mitigate the turbulence issue. Here, we propose and demonstrate Bessel beams enabled DMD-based optical switch to improve the stability and performance of the optical communication in turbulent atmosphere. We statistically characterize the beam wanders of the Gaussian beams and Bessel beams in turbulent atmosphere at the temperatures of 60oC and 80oC. We built the two channels optical switch communication system and measure the bit error rate of the 15Gbit/s OOK signals transmitted by the Gaussian beams and Bessel beams at the temperatures of 60℃ and 80℃, respectively. The optical switch using the Bessel beams shows lower bit error rates with weaker fluctuations compared with the Gaussian beams. The DMD-based optical switch using the Bessel beams has the potential for practical optical communication applications in Datacenter.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Wang Xin-wen   Liu Kangkang   Cheng He-nan   ren wei   xiang jingfeng   Ji Jing-wei   Peng Xiang-kai   Zhang Zhen   zhao jianbo   ye meifeng   Li Lin   Li Tang   wang bin   qu qiuzhi   Liu Liang   lü desheng  

      摘要 + 此论文可免费阅读 (可能需要登录)

A high-performance transportable fountain clock is attractive for use in laboratories with high-precision time-frequency measurement requirements. This letter reports the improvement on stability of a transportable rubidium-87 fountain clock because of an optimization of temperature characteristic. This clock integrates its physical packaging, optical benches, microwave frequency synthesizers and electronic controls onto an easily movable wheeled plate. Two optical benches with high vibration resistance is realized in this work. No additional adjustment is required after several times movement of them. The Allan deviation of the fountain clock frequency was measured by comparing it with that of the hydrogen maser. The fountain clock got a short-term stability of 2.3×10⁻¹³@1s and long-term stability to the order of 10⁻¹⁶@100000s

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Kong Qian   Zhan Yafeng   Wan Peng  

      摘要 + 此论文可免费阅读 (可能需要登录)

We report on a DCN architecture based on hybrid Optical Circuit Switching (OCS) and Optical Burst Switching (OBS) interconnect for dynamic DCN connectivity provisioning. With the combination of the centralized and distributed control of the Software Defined Optical Networks (SDON), the proposed interconnect can achieve unprecedented flexibility in dealing with both mice and elephant flow in the DCN. Numerical simulation is employed to investigate the performance of the proposed architecture. The results show that OBS module has preferable performance in dealing with larger burst packet, and the throughput is constrained by the capacity of the server Random Access Memory (RAM) module.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Cen Yuan   Xie Jianlan   Liu Jianjun  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this Letter, a photonic crystal (PC) flat lens with scatterer-size-gradient is proposed, which simultaneously achieve imaging of point source and sub-wavelength focusing of plane wave in the first, the second and the fifth bands. The imaging of point source breaks through the diffraction limit in the second and the fifth bands. The PC flat lens with scatterer-size-gradient is expected to be used to new multifunctional optical imaging and focusing device, which improves the application potential of PC flat lens.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Gao Xin-Xia   Cui Jin-Ming   Huang Yunfeng   Li Chuanfeng   Guo Guangcan  

      摘要 + 此论文可免费阅读 (可能需要登录)

We have demonstrated a mode matching method between two different fibers by a hybrid thermal expanded core (TEC) technique, which can be applied to match the modes of fiber-based Fabry-P\'erot cavities (FFPCs). Experimentally, this method has achieved an expansion of the ultraviolet fiber core by 3.5 times while keeping fundamental mode propagation. With the experiment parameters, the fundamental mode coupling efficiency between the fiber and micro-cavity can reach 95% for a plano-concave cavity with a length of 400 \mum. This method can not only have potential in quantum photonics research, but also can be applied in classical optical fields.

       PDF全文        Chinese Optics Letters ，2019年第17卷第9期 pp.09      

Xia Renjie   Wang Changshun   Chen Tianyu   Pan Yujia   Lyu Ziyao   Sun Lili  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this paper, an all-optical logic sequence generator based on two different polarization holographic gratings has been proposed and demonstrated, which has one input port and four output ports. The polarization state of input light signal determines logic output signals. It can produce four kinds of logic sequence output signals: 1000, 0100, 0010, and 0001, corresponding to the input light signal of four different polarization states: the p-linear, s-linear, left-handed circular, and right-handed circular. The two polarization gratings have been recorded and the working principle of the logic sequence generator has been proved by diffraction pattern analysis of polarization gratings.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Xue Jinxing   Liu Candong   Zeng Zhinan   Li Ruxin   Xu ZhiZhan  

      摘要 + 此论文可免费阅读 (可能需要登录)

We theoretically investigate delay-dependent attosecond transient absorption spectra in the helium atom dressed by an infrared laser pulse in the wavelength range of 800–2400 nm. By numerically solving the three-dimensional time-dependent Schrödinger equation, we find that the absorption spectrogram exhibits a multiple-fringe structure for using the longer-wavelength dressing pulse. The quantitative calculation of the transition matrix between different Floquet states provides direct evidence on the origin of the multiple-fringe structure. Our result shows that the wavelength of the dressing pulse is an important parameter and the unique feature of attosecond transient absorption spectroscopy can be induced in the mid-infrared regime.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Wang Guoyan   Jiang Lan   Sun Jingya   Hu Jie   Wang Qingsong   Li Ming   Lu Yongfeng  

      摘要 + 此论文可免费阅读 (可能需要登录)

Cylindrical shockwave inside PMMA generated simultaneously with two hemispherical shockwaves induced by femtosecond Gaussian beam laser was investigated using ultrafast pump-probe imaging technique. The evolutions of these three shockwaves with probe delay and incident pulse number have been systematically analyzed. The plasma intensity and filament length in the center of cylindrical shockwave both decayed with pulse number. Moreover, the self-focused filament moved downstream towards the output surface with increased pulse number. The experimental results and mechanism illustrated that energy deposition was suppressed by degraded nonlinear effect due to pre-ablated structure in multi-pulses irradiation.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Li Yingyi   Yang Ke   Liu Gaoyou   Yao Baoquan   Ju Youlun  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate a Fe:ZnSe laser gain-switched by a ZnGeP₂ (ZGP) optical parametric oscillator (OPO) under the pulse repetition frequency (PRF) of 1 kHz at room temperature. The 2.9 μm signal light of the OPO is employed as the pump for the Fe:ZnSe laser. The maximum output power of the Fe:ZnSe laser is 58 mW with the pulse duration of 2.7 ns under the incident pump power of 280 mW, corresponding to a peak pulse power of 21.5 kW and an optical-to-optical efficiency of 20.7%. The spectrum of the Fe:ZnSe laser has a range of 4030.2-4593.6 nm with a dip in 4187.1-4340.4 nm due to the absorption of CO₂.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Ji Jianhua   Zhang Jianjia   Wu Bing   Wang Ke   Xu Ming  

      摘要 + 此论文可免费阅读 (可能需要登录)

We experimentally demonstrate a 10 Gb/s FSO wiretap channel based on spatial diversity scheme and optical code division multiple access (OCDMA). In weak and middle turbulence cases, bit error rate of legitimate user can be decreased and physical layer security can be enhanced simultaneously.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

He Xiaopeng   Huang Panhui   Yang Xiaoyu   Jin Zuanming   Lou shitao   Zhang Xiaolei   Jin Qingyuan  

      摘要 + 此论文可免费阅读 (可能需要登录)

The ultrafast spin dynamic of in-plane magnetized Fe/Pt films was investigated by terahertz emission spectroscopy. The amplitude of emitted terahertz wave is proportional to the intensity of the exciting laser beams. Both the amplitude and polarity of the terahertz wave can be adjusted by modifying the external magnetic field. The dependency of the amplitude on external magnetic fields is coincidence to the hysteresis loops of the sample. Also the polarity of terahertz wave is reversed as the magnetization orientation is reversed. The superdiffusive transient spin current with inverse spin Hall effect (ISHE) is attributed to main mechanism of the terahertz emission.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Wang Xiaojing   Ren Huaijin   Wang Gang   He Jun  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this article, a new method is presented to calculate the interactive length between fundamental wave (FW) and second harmonic generation (SHG) for the configuration of total internal reflection on the inner surface of nonlinear crystal. Three independent experiments are designed to measure bandwidths of this second harmonic wave. The theoretical expression of the intensity of SHG is obtained through nonlinear coupled wave equation. By utilizing the measured bandwidths and the intensity equation through mathematical calculation, the interactive length of this phase-matched SHG can be calculated. Because there is no existing method to obtain the interactive length either from the theoretical calculation or experimental measurement. This method can be applied to estimate the extremely short interactive volume in nonlinear processes.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Huang Junchao   Wang Lingke   Duan Yifei   Huang Yafeng   ye meifeng   Li Lin   Liu Liang   Li Tang  

      摘要 + 此论文可免费阅读 (可能需要登录)

Excess frequency noise induced by mechanical vibration is the dominant noise source at low Fourier frequencies in fiber-delay-line (FDL) stabilized lasers. To resolve this problem, a double-winding fiber spool is designed and implemented that has ultralow acceleration sensitivity in all spatial directions. By carefully choosing the optimal geometry parameters of the fiber spool, we achieve acceleration sensitivity of 8 × 10−11/g and 3 × 10−11/g in axial and radial directions, respectively.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Liu xiaojuan   Hu Ping   Huang Yan   Liu Fangfang   Liu Ying   Guo Liping   Ge Xiaolu  

      摘要 + 此论文可免费阅读 (可能需要登录)

A passively Q-switched erbium-doped fiber laser is proposed and demonstrated utilizing a Zirconium Disulfide (ZrS2)-based saturable absorber. ZrS2 nanosheets are prepared whose modulation depth, saturation intensity and nonsaturable absorbance are measured to be 14.7%, 0.34 MW/cm2 and 17.4%, respectively. Then, a Q-switched EDF laser is implemented by the ZrS2-SA. The pulse repetition rate varies from 40.65 kHz to 87.1 kHz when the pump power changes from 55 mW to 345 mW. The shortest pulse width is 1.49 μs with pulse energy of 33.5 nJ. As far as we know, this is the shortest pulse width obtained by ZrS2-SA so far.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Fu Shiyao   Zhai Yanwang   Zhou Heng   Zhang Jianqiang   Yin Ci   Gao Chunqing  

      摘要 + 此论文可免费阅读 (可能需要登录)

Multi-ring optical vortices are a kind of structured beams that carry orbital angular momentum (OAM) and have concentrical doughnut intensity distributions. In this paper, we present both theoretically and experimentally a scheme that employing the dimensions of both the OAM states and radial index of multi-ring optical vortices simultaneously to accomplish high-dimensional free-space data coding/decoding transmissions. Such scheme can further improve the coding efficiency when limited OAM states are available. In the proof-of-concept experiment, 64-ary coding/decoding employing 16 OAM states and 4 radial indices are present. And the coding/decoding performance when facing various atmosphere turbulence is evaluated. Furthermore, a 64×64 gray image (totally 32768 bits) is also transmitted through multi-ring optical vortices coding in free-space successfully, showing good transmission performance.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

tellal azeddine   ziane omar   Baldeck Patrice  

      摘要 + 此论文可免费阅读 (可能需要登录)

The diffraction of a dielectric microline pair is optimized by numerical simulations to generate an efficient focusing pattern with a micron-scale footprint. Microlines separated by 1.12 µm are fabricated by two-photon polymerization on a glass substrate, and their diffraction pattern is characterized by 3D wide-field transmission microscopy. A line pair, having a width W = 0.4 µm and a height H = 0.8 µm, leads to a diffraction-limited focusing in the visible spectrum. Depending on wavelength, its focal length, lateral resolution, and depth of focus are in the ranges of 0.8-1.3 µm, 0.22-0.44 µm, and 1.7-2.13 µm, respectively. Such microlens based on the diffraction of only two subwavelength scatterers could be used for the design of miniature optical sensors with micron and sub-micron pixels.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

KOIRALA ISHWOR   Park Chul-Soon   Lee Sang-Shin   Choi Duk-Yong  

      摘要 + 此论文可免费阅读 (可能需要登录)

Angle tolerant transmissive subtractive color filters incorporating a metasurface exploiting hydrogenated amorphous silicon (a-Si:H) nanopillars (NPs) on a glass substrate, were proposed and demonstrated. The achieved transmission efficiency ranged from 75% to 95% at off-resonance wavelengths. For NP resonator, electric and magnetic field distributions in conjunction with absorption cross-sections were investigated to confirm resonant transmission dip which is primarily governed by the absorption resulting from simultaneous excitation of magnetic and electric dipoles via Mie scattering. The proposed devices exhibit higher angular tolerance and lower crosstalk for the absorption spectra and therefore be applicable with photodetectors, image sensors, and imaging/display devices.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Che Abd Rashid Nurfatihah   Ngajikin Nor Hafizah   Azmi Asrul Izam   Arsat Rashidah   Isaak Suhaila   Cholan Noran Azizan   Azmi Nur Ellina  

      摘要 + 此论文可免费阅读 (可能需要登录)

Spectrophotometer with LED being the light source for uric acid detection is proposed in this work. The mechanism of the uric acid detection is based on energy absorbed by sodium urate, which is a chemical product of uric acid and sodium hydroxide (NaOH) solution. For the performance validation, comparison between the spectrophotometer with LED and halogen lamp is carried out. Measurement results suggest that spectrophotometer system with LED light has better sensitivity than that with halogen light. At 460 nm wavelength, the sensitivity for the spectrophotometer with LED is 0.0046 dL/mg, which is 73% higher than that with halogen light that records 0.0012 dL/mg. This enhanced sensitivity is attributed to the higher luminous efficacy of the LED light beam. As a result, a larger amount of flux interacts with the sample, leading to the sensitivity enhancement. The spectrophotometer with LED is also applied for detection of uric acid in real human urine sample. Based on the experimental data at 460 nm wavelength, the method manages to achieve the sensitivity of 0.0016 dL/mg, accuracy of 96.01%, limit of detection (LOD) of 4.79 mg/dL and limit of quantification (LOQ) of 14.52 mg/dL. These findings show that the use of LED as the input light is promising for the spectrophotometer.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Xie Yafeng   Zhang Saifeng   Zhang Xiaoyan   Dong Ningning   Kislyakov Ivan   Luo Song   Chen Zhanghai   Nunzi Jean-Michel   Zhang Long   Wang Jun  

      摘要 + 此论文可免费阅读 (可能需要登录)

Mechanically exfoliated (ME) and chemical vapor deposition (CVD) MoS₂ monolayers have been extensively studied, but the large differences of nonlinear optical performance between them have never been clarified. Here, we prepared MoS₂ monolayers using ME and CVD methods and investigated the two-photon absorption (TPA) response and its saturation. We found TPA coefficient of ME monolayer was about (1.88±0.21)×10³ cm/GW, nearly two times of CVD one, (1.04±0.15)×10³ cm/GW. Furthermore, we simulated and compared the TPA-induced optical pulse modulation in multilayer cascaded structures, which is instructive and meaningful for the design of optical devices such as beam shaper, optical limiter.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Guan Yan   Wang Fang   Yang Ying   Wang De'en   Zhang Xin   Qiang Yuan   Zhou Wei   Hu Dongxia   Deng Xuewei   Ren Huaijin  

      摘要 + 此论文可免费阅读 (可能需要登录)

Collinear phase-matching of sum-frequency generation (SFG) has been studied thoroughly previously, while non-collinear schemes are sometimes more flexible in application. However, this phase-matching type is more difficult to meet and control. We employ a convenient method to obtain harmonic generation in bulk KDP: using an incident wave vector and a reflected wave vector to consist triangle phase-matching relationship. With a simple, flexible set-up, we can observe 351nm SFG and the conversion efficiency is up to ~3.6% per reflection. Furthermore, we believe this approach has potential application value and improvement space.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

li qin   Li Wenbo   Chu Wei   Cao Yuxiang   Zhang Wencheng   Ma Hongliang   Jin Zuanming   Dai Ye  

      摘要 + 此论文可免费阅读 (可能需要登录)

Spatio-temporal coupling characteristics of ultrafast laser pulse are quantitatively tailored. An asymmetric microstructure is induced in the focal volume when laser scans perpendicular to the direction of spatial chirp in fused silica. The tilted direction reverses when adding a Dove prism into the light path. The sign of pulse front tilt can be turned from positive to negative by changing the group delay dispersion by step. We reveal that tilted direction of microstructure depends on spatial chirp and the interplay between spatio-temporal chirp leads to the change of tilted angles.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Liu Shun   Lu Ping   Chen Enci   Ni Wenjun   Liu Deming   Zhang Jiangshan   Lian Zhenggang  

      摘要 + 此论文可免费阅读 (可能需要登录)

This letter shows Vernier effect based on two segments of PANDA polarization maintaining fiber (PMF) whose length is 28 cm and 23 cm, respectively. The two PMF is spliced together and the angle between the fast axes is set to 45°. This cascaded PMF is inserted in a Sagnac loop to form an interferometer which can generate Vernier effect. The spectrum consists of finesse fringe and envelope and realize simultaneous measurement of strain and temperature. The envelope can provide strain and temperature sensitivities of 58.0 pm/με and -1.05 nm/°C. The finesse fringe provides sensitivities of 5.9 pm/με and -1.36 nm/°C.

       PDF全文        Chinese Optics Letters ，2019年第17卷第8期 pp.08      

Guo Hui   He Ruyong   Wei Chaopeng   Lin Zequn   Wang Le   zhao shengmei  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this paper, we propose an advanced framework of ghost edge imaging, named compressed ghost edge imaging (CGEI). In the scheme, a set of structured speckle patterns with pixel shifting are illuminated on an unknown object. The output is collected by a bucket detector without any spatial resolution. By using compressed sensing algorithm, we obtain horizontal and vertical edge information of the unknown object with the bucket detector detection results and the known structured speckle patterns. The edge is finally constructed via two-dimensional edge information. The experimental and numerical simulations results show that the proposed scheme has a higher quality and reduces the number of measurements, in comparison with the existed edge detection schemes based on ghost imaging.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Zhang Yinlong   Liang YiZhi   Jin Long   Guan Bai-Ou  

      摘要 + 此论文可免费阅读 (可能需要登录)

All-optical ultrasound probe, which contains a photoacoustically based ultrasound generator paired with a photonic acoustic sensor, provide promising imaging modality for diagnostic and MRI compatible applications. Here, we demonstrate the fabrication of a fiber-based all-optical ultrasound probe and its application in pulse-echo ultrasound imaging. The ultrasound generator is fabricated on a 125-μm multimode optical fiber by forming a light-absorbing multiwalled carbon nanotubes (MWCNTs)-polydimethylsiloxane (PDMS) composite coating on its distal end. A peak-to-peak acoustic pressure 0.95 MPa has been achieved at nearly the damage threshold 2.46 μJ, by chemically functionalizing the fiber surface to enable strong nanotube adsorption. Ultrasound reception was performed by a fiber-laser ultrasound sensor which translates ultrasound pressure into differential lasing-frequency changes. By linearly scanning the probe, ex vivo two- and three-dimensional imaging of a segment of swine trachea has been demonstrated, by detecting the echo ultrasound signals and reconstructing the acoustic scatters. The probe presents axial and lateral resolutions at 150 and 62 μm, respectively. The small-sized, side-looking all-fiber ultrasound probe presents a promising approach for assembling an interventional endoscopy.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Huang Junchao   Wang Lingke   Duan Yifei   Huang Yafeng   ye meifeng   Liu Liang   Li Tang  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate frequency stabilization of a 1.55 μm erbium-doped fiber laser by locking it to a 5-km-long optical fiber delay line (FDL). The stabilized laser is characterized via comparison with a second identical laser system. We obtain fractional frequency stability of better than 3*10-15 over timescales of 1–10 s and a laser linewidth of 0.2 Hz, which is the narrowest linewidth of an FDL-stabilized laser observed to date.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

huang wei   cui yulong   Li zhixian   zhou zhiyue   Wang Zefeng  

      摘要 + 此论文可免费阅读 (可能需要登录)

We reported here a single-pass 1.56 μm fiber gas Raman laser in a deuterium-filled hollow-core fiber and a 2.86 μm cascade fiber gas Raman laser with methane in the second stage. The maximum output power of 1.56 μm and 2.86 μm is 27 mW and 8.5 mW with Raman conversion efficiency of 30% and 42% respectively. The results offer a new method to produce 1.5 μm fiber source and prove the potential of the cascade fiber gas Raman laser in extending the available wavelength.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Zhang Min   Xu Bo   Li Xiaoyun   Cai Yi   Wu Baojian   Qiu Kun  

      摘要 + 此论文可免费阅读 (可能需要登录)

A novel predictive dynamic bandwidth allocation (DBA) method based on Long Short-Term Memory (LSTM) neural network is proposed for 10-Gigabit-capable passive optical network in mobile front-haul (MFH) links. By predicting the number of packets that arrive at the optical network unit buffer based on LSTM, the round-trip time delay in traditional DBAs can be eliminated to meet the strict latency requirement for MFH links. Our study shows that LSTM has better performance than feed-forward neural network. Based on extensive simulations, the proposed scheme is found to be able to achieve the latency requirement for MFH and outperforms the traditional DBAs in terms of delay, jitter and packet loss ratio.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Lu Chenghao   Zhu Bing   Zhu Chuanyi   Ge Licheng   Liu Yi'an   Chen Yuping   Chen Xianfeng  

      摘要 + 此论文可免费阅读 (可能需要登录)

All-optical logic gates including AND, XOR, and NOT gates, as well as a half-adder, are realized based on two-dimensional lithium niobate photonic crystal (PhC) circuits with PhC micro-cavities. The proposed all-optical devices have an extinction ratio as high as 23 dB due to the effective all-optical switch function induced by two-missing-hole micro-cavities. These proposed devices can have potential implementation of complex integrated optical functionalities including all-optical computing in lithium niobate slab or thin film.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Wang Aimin   Yang Wan   Wu Danlei   Wu Runlong   Liu Guanyu   Chen Bingying   Feng Lishuang   Zhang Zhigang  

      摘要 + 此论文可免费阅读 (可能需要登录)

We present a Er:fiber based femtosecond laser at 780 nm with 256-MHz repetition rate, 191-fs pulse duration, and over 1-W average power. Apart from the careful third-order dispersion management, we introduce moderate self-phase modulation to broaden the output spectrum of the Er:fiber amplifier and achieve 193-fs pulse duration and 2.43-W average power. Over 40% frequency doubling efficiency was obtained by a periodically poled lithium niobate crystal. Delivering through a hollow-core photonics bandgap fiber, this robust laser becomes an ideal and convenient light source for two-photon autofluorescence imaging.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Zhang Pan   Liu Dean   Yang Aihua   Zhu Jianqiang  

      摘要 + 此论文可免费阅读 (可能需要登录)

A method is proposed to optimize the recording structure of the photorefractive volume grating to compensate the high spatial frequency in the distorted wavefront by optical phase conjugation. Based on coupled-wave equation, the diffraction efficiency of the recorded grating formed by the scattered beams in different recording structures is simulated. The theoretical results show that the recorded modulations with high spatial frequency can be significantly improved in the small recording angle. In experiment, three recording structures with the recording angle 7.5°, 30° and 45° are chosen to verify the compensation effect. Compared with the reconstructed image in the large recording angle 45°, the signal to noise ratio of image recorded in 7.5° increases to 3.2 times.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Sun Xiaocong   Wang Yajun   Tian Long   Zheng Yaohui   Peng Kunchi  

      摘要 + 此论文可免费阅读 (可能需要登录)

Squeezed states belong to the most prominent nonclassical resources. They have compelling applications in precise measurement, quantum computation and detection. Here, we report on the direct measurement of 13.8 dB squeezed vacuum states by improving the interference eciency and gain of balanced homodyne detection. By employing an auxiliary laser beam, the homodyne visibility is increased to 99.8%. The equivalent loss of the electronic noise is reduced to 0.05% by integrating a junction eld-eect transistor (JFET) buering input and another JFET bootstrap structure in the balanced homodyne detector.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Miao Runlin   Tong Mingyu   Yin Ke   Ouyang Hao   Wang Zhenyu   Zheng Xin   Cheng Xiangai   Jiang Tian  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this work, a soliton mode-locked erbium-doped fiber laser (EDFL) with a high-quality molecular beam epitaxy (MBE) grown topological insulator (TI) Bi2Se3 saturable absorber (SA) is reported. To fabricate the SA device, a 16-layer Bi2Se3 film was grown successfully on a 100 μm thick SiO2 substrate and sandwiched directly between two fiber ferrules. The TI-SA had a saturable absorption of 1.12 % and a saturable influence of 160 MW/cm2. After inserting the TI-SA into the unidirectional ring-cavity EDFL, self-starting mode-locked soliton pulse trains were obtained at a fundamental repetition rate of 19.352 MHz. The output central wavelength/pulse energy/pulse duration/signal to noise ratio (SNR) of radio frequency spectrum were 1530 nm/18.5 pJ/1.08 ps/60 dBm, respectively. These results demonstrate that MBE technique could provide a controllable and repeatable method for the fabrication of identical high-quality TI-SAs, which is critical important for ultrafast pulse generation.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Wang Yan   Lin Nan   Gao Wanli   Song Huanyu   Hu Minglie   Li Haiming   Bao Wenxai   Ma Xiaoyu   Zhang Zhigang  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate a strain compensated long lifetime SESAM with a high modulation depth for fiber lasers. The SESAM was measured to have a damage threshold of 9.5 mJ/cm², a modulation depth of 11.5%, a saturation fluence of 39.3 µJ/cm², and an inversed saturable absorption coefficient of 630 mJ/cm². The SESAM has been applied to a linear cavity mode-locked Yb:fiber laser, which has been working for more than a year without damage of the SESAM.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Sun ShengZhi   Ye Song   Wang Zhenyan   Song Juan   Qian Bin   Qiu Jianrong  

      摘要 + 此论文可免费阅读 (可能需要登录)

We report on the elemental redistribution behavior in oxyfluoride glasses with a high repetition rate near-infrared femtosecond laser. Elemental analysis by Electro-Probe Microanalyzer demonstrates that the redistributions of Ca2+ and Yb3+ ions change dramatically with pulse energy, which are quite different compared with previous reported results. Confocal fluorescence spectra of Yb3+ ions demonstrate that the luminescence intensity changes obviously with the elemental redistribution. The mechanism of the observed phenomenon is discussed. This observation may have potential applications in the fabrication of micro-optical devices.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Xu Aopeng   Kong Delong   Fu Zhijie   Wang Zhaoying   Lin Qiang  

      摘要 + 此论文可免费阅读 (可能需要登录)

For most of atom interferometers, vibration isolation unit is applied to reduce vibration noise. In our experiment, instead of isolation, the vibration signals are monitored, combining with the sensitive function, the compensation phase shift for the atom interferometer is obtained. We focused on the correction over a wide spectrum rather than on “monochromatic” frequencies. The sensitivity of the atom gravimeter can be upgraded by a factor of more than two. Furthermore, we demonstrated that the atom interferometer can still produce a good measurement result without passive vibration isolation in extremely noisy environments by using vibration compensation.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Li Jian   Xu Yang   Zhang Mingjiang   Zhang Jianzhong   Qiao Lijun   Wang Tao  

      摘要 + 此论文可免费阅读 (可能需要登录)

We propose and experimentally demonstrate a novel Raman-based distributed fiber-optics temperature sensor for improving the temperature measurement accuracy and engineering applicability. The proposed method is based on the double-ended demodulation with a reference temperature and dynamic dispersion difference compensation method, which can suppress the effect of local external physics perturbation and intermodal dispersion on temperature demodulation results. Moreover, the system can omit the pre-calibration process by using the reference temperature before the temperature measurement. The experimental results of dispersion compensation indicate that the temperature accuracy optimizes from 5.6 ℃ to 1.2 ℃, and the temperature uncertainty decreases from 16.8 ℃ to 2.4 ℃. Moreover, the double-end configuration can automatically compensate the local external physics perturbation of the sensing fiber, which exhibits a distinctive improvement.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Zhang Yuxia   Yang Yilun   Zhang Lianhan   Lu Dazhi   Xu Min   Hang Yin   Yan Shishen   Yu Haohai   Zhang Huaijin  

      摘要 + 此论文可免费阅读 (可能需要登录)

Praseodymium ion doped gain materials have the superiority of lasing at various visible wavelengths directly. Simple and compact visible lasers are booming with the development of blue laser diodes in recent years. In this paper, we demonstrate the watt level red laser with a single blue laser diode and Pr:YLF crystal. On this basis, the passively Q-switched pulse lasers are obtained with monolayer graphene and Co:ZnO thin film as the Q-switchers in the visible range.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Wang Meng   Wang fan   Feng Suya   Yu Chunlei   Wang Shikai   Zhou Qinling   Zhang Lei   Lou Fengguang   Chen Danping   Hu Lili  

      摘要 + 此论文可免费阅读 (可能需要登录)

A large-mode-area (LMA) ytterbium doped photonic crystal fiber (PCF) with core NA of 0.034 and core diameter of 50 μm was made by stack-and-draw technique. The core is formed by Yb3+/Al3+/F-/P5+ co-doped silica glass containing 0.09 mol% Yb2O3 with absorption coefficient at 976 nm up to 3.2 dB/m. The core glass with homogeneous distribution of Yb3+ ions and refractive index difference of 4×10-4 compared with pure silica was prepared by sol-gel method and heat homogenization at 2000°C. Laser power amplification of this LMA PCF was studied using a seed source of 21 picosecond pulse duration and 48.7MHz repetition rate at 1030 nm wavelength. With pump power of 520 W, a maximum 272 W (266 KW peak power) quasi single-mode laser output with M2 of 2.2 was achieved in a 4.7 m fiber length bent at a diameter of 47 cm with slope efficiency of 52%, and no obvious mode instability, SRS or thermal damage on end facet of fiber were observed.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Ruan Cunjun   Kong Deyin   Dai Jun   Chen Kanglong   Guo Sujie   Wu Xiaojun  

      摘要 + 此论文可免费阅读 (可能需要登录)

The high-resolution frequency domain spectroscopy (FDS) is set up using coherent and continuous wave terahertz emitter and receiver. Terahertz waves are generated and detected by two photomixers with two distributed feedback (DFB) lasers. Atmospheric water vapor with different relative humidity is systematically investigated by the FDS. A high frequency resolution of ~14 MHz is obtained with the help of Hilbert transformation, leading a well resolved and distinct transmittance characterization of water vapor. Compared with conventional THz time domain spectroscopy (TDS), the high-resolution continuous wave THz spectrometer is one of the most practical system in gas-phase molecular sensing, identification, and monitoring.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Li Zhigang   Yang Rui   Sun Meiyu   Han Jing   Zhang Dengying   chen jiannong   Zhang Dawei   Zhu Linwei  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this letter, we propose a simple and effective approach for transforming conventional Talbot array illuminator (TAI) with multilevel phase steps into a binary-phase Talbot array illuminator (BP-TAI) through the detour phase encoding. The BP-TAI is a binary (0 π) phase-only diffractive optical element, which can be utilized to generate a large-scale focal spots array with a high compression ratio. As an example, we design a square BP-TAI with the fraction parameter β=15 for achieving a square multifocal lattice with a high compression ratio β^2. Theoretical analysis and experimental results demonstrate that the detour phase encoding is efficient for designing the BP-TAI, especially with the high compression ratio. Such results may be exploited in practical large-scale optical trapping and X-ray imaging.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Ruan Zuliang   Pei Li   Zheng Jingjing   Wang JianShuai   Wu Liangying   Ning Tigang   Wang Ji  

      摘要 + 此论文可免费阅读 (可能需要登录)

A refractive index intensity detecting sensor with long-period grating written in the single mode - thin core - single mode fiber structure is proposed and optimized theoretically. The sensor is composed of two single-mode fibers connected by a section of long period fiber grating fabricated on thin-core fiber. After optimization and benefit from phase matching point, the loss peak of the structure can reach to 62.8dB theoretically. The wavelength of the characteristic peak is fixed at the phase matching point, so the intensity detection can be achieved. The sensitivity can reach to 272.5dB/RIU. The structural optimization of this paper provides a reference for the fabrication of an easy-made all-fiber sensor without extra cladding.

       PDF全文        Chinese Optics Letters ，2019年第17卷第7期 pp.07      

Li Min   Liu Xin   Zhang Ang   Xian Hao  

      摘要 + 此论文可免费阅读 (可能需要登录)

The precise alignment of high-performance telescope is a key factor to ensure the imaging quality. However, for telescopes with wide field of view, the images are sometimes under-sampled. To study the effects of under-sampled images on the precision of telescope alignment, numerical simulations are implemented with stochastic parallel gradient descent (SPGD) algorithm. The results show that the alignment program can converge stably and quickly. However, with the reduction of full width at half maximum (FWHM) of images, the relative residual errors increase from 9.5% to 19.5%, and the wavefront errors raise from 0.0972λ to 0.1074λ, indicating the accuracy of alignment decreases.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Zheng Yu   Sun Fang-Wen  

      摘要 + 此论文可免费阅读 (可能需要登录)

Forward-scattering-light interferometry has become the most commonly used position detection scheme in optical levi-tation system. Usually, 3-set detectors are required to obtain the 3-dimensional motion information. Here, we simplify the 3-set detectors to one set by inserting a Dove prism. With an optical levitation system in vacuum, we investigate the role of Dove prism in the position measurement process. The relationship between power spectral density and ro-tation angle of Dove prism is experimentally demonstrated and analyzed. This work shows that the Dove prism can much reduce the complexity of experimental setup, which can be applied in the compact optical levitation system for studies in metrology, quantum physics and biology.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Hou Zhi-Shan   Cao Jia-Ji   Li Aiwu   Yang Han  

      摘要 + 此论文可免费阅读 (可能需要登录)

Based on natural protein materials, a series of lenses with different height and focal length were assembled on glass substrates by femtosecond laser non-contact, masking and cold processing. This lens array itself possesses unique and characteristic optical performance in three-dimensional parallel imaging and bending imaging. What is more profound is that by using equilibrium swelling of protein-hydrogel, once the lens array was placed in liquid environment, with the change of ion concentration (eg. pH), the refractive index and curvature of the protein-hydrogel would change, which leads to the flex of focal plane of the lens, finally realizes the dynamically tunable of protein microlens. These smart stress device may have great potential in optical biosensing and microfluidic chip integrated field.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Wu Chenchen   Liu Ning   Hu Hai   Guo Xiangdong   Liao Baoxin   Liu Jiaming   Wang Liming   Chen Chunying   Yang Xiaoxia   Dai Qing  

      摘要 + 此论文可免费阅读 (可能需要登录)

Abstract: Monitoring the chemical and structural changes in protein side chains and endpoints by infrared spectroscopy is important to study the chemical reaction and physical adsorption process of proteins. However, the detection of side chains and endpoints in nanoscale proteins is still challenging due to its weak infrared response. Here, by designing a double-layered graphene plasmon sensor on MgF2/Si substrate in the IR fingerprint region, we detect the vibrational modes in side chains and endpoints (1397 cm-1 and 1458 cm-1) of monolayer protein. The sensor could be applied on biochemistry to investigate the physical and chemical reaction of biomolecules.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Pan Yijie   Liao Wenhan   Wang He   Yao Yan   Cai Jinhui   Qu Jifeng  

      摘要 + 此论文可免费阅读 (可能需要登录)

Atomic Doppler broadening thermometry(DBT) potentially is an accurate and practical approach for the thermodynamic temperature measurement. However, previous reported atomic DBT had a long acquisition time and had only been proved at the triple point of water, 0℃, for the purpose of determination of the Boltzmann constant. This research implemented the Cesium atomic DBT for fast room temperature measurement. Cs133 D1(6S1/2→6p1/2 transition) line was measured by direct laser absorption spectroscopy, and quantity of thermal-induced linewidth broadening was precisely retrieved by the Voigt profile fitting algorithm. The preliminary results showed the proposed approach had a 4 minutes single-scan acquisition time and a 0.2% reproducibility. It is expected that the atomic DBT could be used as an accurate, chip-scale, and calibration-free temperature sensor and standard.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Sun Yuxiang   Wang Mengxia   Wang Xinle   Zhou Ying   Wang Bo   Wang Zhengping   Yu Fapeng   Xu Xinguang  

      摘要 + 此论文可免费阅读 (可能需要登录)

With tin diselenide (SnSe2) film as saturable absorber (SA), the passively Q-switched self-frequency doubling (SFD) lasers were realized in Nd3+:ReCa4O(BO3)3 (Re = Y, Gd) crystals. For Nd:YCOB crystal, the maximum average output power at 532 nm was 19.6 mW, and the corresponding pulse repetition frequency, pulse duration, single pulse energy and peak power were 17.6 kHz, 91.9 ns, 1.1 µJ, 12.1 W, respectively. For Nd:GdCOB crystal, these values were 14.5 mW, 22.1 kHz, 48.7 ns, 0.66 µJ and 13.5 W.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Hu Hai   Zhao Jianyang   Wang Weimin   Ho James   Kuang Langxing   Liu Wenbin  

      摘要 + 此论文可免费阅读 (可能需要登录)

High power LASER diodes (LD) with a lasing wavelength between 700-780 nm have great potential in various medical use. Here we report our recent efforts in developing InGaAsP/AlGaInP based commercial high power edge-emitting LD which has 755 nm emission peak with a world-record continuous wave (CW) output power of 12.7 W, the highest reported so far. The lack of Al atoms in active region significantly lowers the chance of catastrophic optical damage (COD) during high power laser operation. Meanwhile, with accumulated 3800 running hours, our ongoing aging tests reveal excellent reliability of our devices.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Hu Kai   Yi Lilin   Wei Wei   Hu Weisheng  

      摘要 + 此论文可免费阅读 (可能需要登录)

We propose a general guideline on the design of stimulated Brillouin scattering (SBS) based microwave photonic filter (MPF) using directly-modulated pump. Filter gain profiles and passband ripples with the waveform repetition periods of the driving current ranging from 2 ns to 100 ns are measured after transmission of different fiber length. The results show that the filter performance has nothing to do with the fiber length and the DAC bandwidth requirement for the driving current is no more than 500MHz. Therefore the low cost, flexible reconfiguration and miniaturization characteristics make SBS filter using directed-modulated pump a promising choice as MPF.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Lu Hao   Wu Ying   xie wenjing   tang qi   Han Caiqin   Liu Ying  

      摘要 + 此论文可免费阅读 (可能需要登录)

The changes of mechanical properties and biological activities of monomeric erythrocytes are studied using the optical tweezers micromanipulation technology. Firstly, the mechanical properties of irradiated erythrocyte membranes are obtained. Weaker power laser irradiation can delay the decay of the mechanical properties of erythrocytes, and promote the biological activity of erythrocytes, while higher power laser irradiation damages erythrocytes. The stronger the laser irradiation is, the more obvious and rapid the damage will be. The temperature of the cell surface will be changed by regulating the laser power and irradiation time, so the biological functions of erythrocyte can be controlled. Secondly, the finite element simulation of the temperature change on the cell surface under the condition of laser irradiation is carried out using a simulation software, and the precise temperature of the cell surface irradiated cumulatively by a laser with different powers is obtained. Finally, the processes of abscission, unfolding and denaturation of hemoglobins in erythrocytes at different temperatures due to the photothermal effect are analyzed using the model. The mechanism of the laser irradiation on the elasticity of erythrocyte membranes is also obtained.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Zhang Haifeng   Long Mingliang   Deng Huarong   Wu Zhibo   Chen zhi'en   Zhang Zhongping  

      摘要 + 此论文可免费阅读 (可能需要登录)

Space debris laser ranging was achieved with a 60-W, 200-Hz, 532-nm nanosecond slab, single-frequency green laser at the Shanghai Astronomical Observatory's 60-cm satellite laser ranging system. There were 174 passes of space debris measured in 2017, with the minimum radar cross section (RCS) being 0.25 m², and the highest ranging precision up to 13.6 cm. The RCSs of space debris measured with the farthest distances in 174 passes was analyzed. The results show that the farthest measurement distance (R) and RCS (A) was fitting to R=1388.159A^0.24312, indicating that this laser can measure the distance of 1388.159 km at a RCS of 1 m², which is very helpful to surveillance and research on low-Earth-orbit space debris.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

Lu Tingting   Ma Jian   Zhu Xiaolei   Chen Weibiao  

      摘要 + 此论文可免费阅读 (可能需要登录)

An external frequency doubling electro-optically Q-switched Nd:YAG 473 nm blue laser was demonstrated. With absorbed pump energy of 48 mJ at 100 Hz repetition rate, about 2 mJ of 473nm blue laser pulse energy was achieved by cascade frequency doubling. The second harmonic conversion efficiency was 64.5% and overall optical-optical efficiency was 4.2%, respectively. The blue laser pulse width was less than 10ns and beam quality factor was less than 2.4.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

Song Wei   Zheng Shanguang   Fu Yanan   Min Changjun   Zhang Yuquan   Xie Zhenwei   Yuan Xiao-Cong (Larry)  

      摘要 + 此论文可免费阅读 (可能需要登录)

Controlling both amplitude and phase of light in subwavelength scale is a challenge for traditional optical devices. Here we propose and numerically investigate a novel plasmonic meta-hologram, demonstrating broadband manipulation of both phase and amplitude in subwavelength scale. In the meta-hologram, phase modulation is achieved by the detour phase distribution of unit cells, and amplitude is continuously modulated by a T-shaped nano-cavity with tunable plasmonic resonance. Compared to phase-only hologram, such meta-hologram could reconstruct 3D images with higher signal-to-noise ratio and better image quality, and thus offering great potential in applications such as 3D displays, optical communications, and beam shaping.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Luo Peng   Hao Qiang   Fu Hanmei   Zeng Heping  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate here an environmentally stable and extremely compactable Er-doped fiber laser system capable of delivering sub-100-fs temporal duration at repetition rate at 10 MHz. This laser source employs a SESAM mode-locked soliton laser to generate seed pulses. A single-mode-fiber (SMF) amplifier and a double-cladding fiber (DCF) amplifier (both with double-pass configuration) are bridged by a divider and used to manage the dispersion map and boost the soliton pulses. With the help of ×64 replicas, as high as 60-nJ energy within 95-fs duration are obtained at 10 MHz, corresponding to 600-kW peak power.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Yuan 元晴晨 Qingchen   Liang 方亮 Fang   Zhao 赵强 Qiang   Wang 王亚东 Yadong   Mao 毛博 Bo   Khayrudinov Vladislav   Lipsanen Harri   Sun 孙志培 Zhipei   Zhao Jianlin   Gan Xuetao  

      摘要 + 此论文可免费阅读 (可能需要登录)

The position-dependent mode couplings between a semiconductor nanowire (NW) and a planar photonic crystal (PPC) nanocavity are studied. By scanning a NW across a PPC nanocavity along the hexagonal lattice's Γ-M and M-K directions, the variations of resonant wavelengths, quality factors, and mode volumes in both fundamental and second-order resonant modes are calculated, implying optimal configurations for strong mode-NW couplings and light-NW interactions. For the fundamental (second-order) resonant mode, scanning a NW along the M-K ( Γ-M ) direction is preferred, which supports stronger light-NW interactions with larger NW-position tolerances and higher quality factors simultaneously. The simulation results are confirmed experimentally with good agreements.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Han Yuxiao   Gu Bing   Zhang Shuai   Rui Guanghao   He Jun   Cui Yiping  

      摘要 + 此论文可免费阅读 (可能需要登录)

Understanding the nonlinear optical effect of novel materials plays a crucial role in the fields of photonics and optoelectronics. Herein, we theoretically and experimentally investigate the simultaneous presence of third-order locally refractive nonlinearity and thermally induced nonlocal nonlinearity saturation. We present analytical expressions for the closed-aperture Z-scan trace and the number of spatial self-phase modulation (SSPM) rings, which allows one to unambiguously and conveniently separate the contributions of local and nonlocal nonlinear refraction in the case that both effects occur simultaneously. As a test, we study both the local and thermally induced nonlocal nonlinear refraction in fullerene/toluene solution by performing continuous-wave Z-scan and SSPM measurements at two different wavelengths. This work enriches the understanding of physical mechanism of optical nonlinear refraction effect in solution dispersions of nanomaterials which can be exploited for nonlinear photonic devices.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Mandal Gour   Mukherjee Rahul   Mallick Khaleda   Mandal Paulomi   Patra Ardhendu  

      摘要 + 此论文可免费阅读 (可能需要登录)

We have projected and verified a bidirectional intra-/inter-radio-access-technology carrier-aggregation method for next-generation heterogeneous mobile network supported Filter-bank multi-carrier. Successful transmission of intra/inter-band carrier-aggregation between five broadband FBMC signal and three bands 4G-LTE-A signal over 50-km SMF plus 10-m free-space are successfully broadcasted by employing incoherent light-injection scheme in downlink. In uplink, two intra-bands carrier-aggregated WLAN IEEE 802.11g signal is carried over the equal distance. High receiver sensitivity, low EVM, clear constellation diagrams show successful delivery of different wireless services for different consumers. Therefore, proposed hybrid-system should become potential solution for future mobile-fronthaul network because of its low latency and high-capacity.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Qian Guang   Niu Bin   Wu Zhao   Kan Qiang   Gu Xiaowen   Zhou Fengjie   Kong Yuechan  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this paper, we reported the preliminary results of an integrating periodically capacitive-loaded travelling wave electrode (CL-TWE) Mach-Zehnder modulator (MZM) based on InP-based multiple quantum well (MQW) optical waveguides. The device configuration mainly includes an optical Mach-Zehnder interferometer (MZI), a direct current (DC) electrode, two phase electrodes and a CL-TWE consisting of a U-electrode and an I-electrode. The modulator was fabricated on 3-inches InP epitaxial wafer by standard photolithography, ICP dry etching, wet etching, electroplating and etc. Measurement results show that the MZM exhibits a 3 dB electro-optic bandwidth of about 31 GHz, a Vπ of 3 V, and an extinction ratio of about 20 dB.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

li long   pan yan   Cui yang   liu rong   yang cheng   liu lan   tian yingzhong   wang bin  

      摘要 + 此论文可免费阅读 (可能需要登录)

The Depth of Focus (DFF) is a technique for estimating the depth and 3D shape of an object from a multi-focus image sequence. At present, focus evaluation algorithms based on DFF technology will always cause inaccuracies in deep map recovery from image focus. There are two main reasons behind this issue. The first is that the window size of the focus evaluation operator has been fixed. Therefore, for some pixels, enough neighbor information cannot be covered in a fixed window and is easily disturbed by noise, which results in distortion of the model. For other pixels, the fixed window is too large, which increases the computational burden. The second is the level of difficulty to get the full focus pixels even though the focus evaluation calculation on the actual calculation process has been completed. In order to overcome these problems, an adaptive window iteration algorithm is proposed to enhance image focus for accurate depth estimation. This algorithm will automatically adjust the window size based on gray differences in a window that aims to solve the fixed window problem. Besides that, it will also iterate evaluation values to enhance the focus evaluation of each pixel. Comparative analysis of the evaluation indicators and model quality has shown the effectiveness of the proposed adaptive window iteration algorithm.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Huang Yong   Wu Chuanchao   Xia Shaoyan   Liu Lu   Chen Shanlin   Tong Dedi   Ai Danni   Yang Jian   Wang Yongtian  

      摘要 + 此论文可免费阅读 (可能需要登录)

Vascular Doppler optical coherence tomography (DOCT) images with weak boundaries are usually difficult for most algorithms to segment. We propose a modified random walk algorithm (MRW) with a novel regularization for the segmentation of DOCT vessel images. Based on MRW, we perform automatic boundary detection of vascular wall from intensity images and boundary extraction of blood flowing region from Doppler phase images. Dice coefficient, sensitivity coefficient and specificity coefficient were adopted to verify the segmentation performance. Experimental study on DOCT images of the mouse femoral artery, showed the effectiveness of our proposed method, yielding 3D visualization and quantitative evaluation of the vessel.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

Xia Huijuan   Yang Shumin   Wang Liansheng   Zhao Jun   Xue Chaofan   Wu Yanqing   Tai Renzhong  

      摘要 + 此论文可免费阅读 (可能需要登录)

Achromatic Talbot lithography (ATL) with high resolution has been demonstrated to be an excellent technique for large area periodic nano-fabrication. In this work, the uniformity of pattern distribution in ATL was studied in detail. Two ATL transmission masks with ~50% duty cycle in square lattice were illuminated by a spatial coherent broadband EUV beam with a relative bandwidth of 2.38%. Nonuniform dot size distribution were observed by experiments and FDTD simulations. The sum of the two kind of diffraction patterns, with different lattice direction (45° rotated) and different intensity distribution, results in the final nonuniform pattern distribution.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Song Weitao   Cheng Qijia   Liu Yue   Zheng Yuanjin   lin zhiping   Wang Yongtian  

      摘要 + 此论文可免费阅读 (可能需要登录)

We proposed a three-dimensional (3D) image authentication method using binarized phase images in a double random phase integral imaging (InI). Two-dimensional (2D) element images obtained from integral imaging are encoded using a double random phase encryption (DRPE) algorithm. Only part of the phase information is used in the proposed method rather than using all of the amplitude and phase information, which can make the final data spare and beneficial to data compression, storage, and transmission. Experimental results verified the method, and successfully proved the developed 3D authentication process using a nonlinear cross correlation method.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

Wang Xiangchuan   Li Shupeng   Jiang Xin   Hu Jintao   Xue Min   Xu Shangzhe   Pan Shilong  

      摘要 + 此论文可免费阅读 (可能需要登录)

Optoelectronic components and subsystems such as optically controlled phased array antennas, distributed radar networks, interferometric optical fiber hydrophones and high-speed optoelectronic chips demand for high accuracy optical time delay measurement with large measurement range and capability for single-end and wavelength-dependent measurement. In this paper, the recent advances in the optical time delay measurement of fiber link with high accuracy are reviewed. The general models of the typical time delay measurement technologies are established with the operational principle analyzed. The performance of these techniques is also discussed.

       PDF全文        Chinese Optics Letters ，2019年第17卷第6期 pp.06      

Zhao Zhigang   Kuroda Kenta   Harasawa Ayumi   Kondo Takeshi   Shin Shik   Kobayashi Yohei  

      摘要 + 此论文可免费阅读 (可能需要登录)

A monolithic Lens-Window-Prism (LWP) device, made of lithium fluoride (LiF) or magnesium fluoride (MgF2), was proposed. When either of the devices was fixed onto one end of a gas cell filled with Xe, it becomes a “wedge-crystal” like device and was used to convert a 1-MHz femtosecond 347 nm laser to its third harmonic radiation at 10.7 eV. This led to an improved beam profile, a more compact and less lossy configuration. A stable output power of ~11 μW was demonstrated for 2 hours using LiF-LWP. In addition, MgF2-LWP was also verified for its practicability at 10.7 eV.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

chang yawei   jiang tongxiao   Zhang Zhigang   Wang Aimin  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate an all-fiber Yb:fiber frequency comb with nonlinear-amplifying-loop-mirror based Yb:fiber laser oscillator. The fiber-spliced hollow-core photonic bandgap fiber was used as dispersion compensator, which was also directly spliced to a piece of tapered photonic crystal fiber for octave-spanning spectrum. The spectrum of the compressed 107 fs laser pulses was broadened, covering 600 nm to 1300 nm in a high-nonlinearity tapered fiber for f to 2f beating. The signal-to-noise ratio of offset frequency was measured to be 22 dB.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

Tsang Peter   Poon T.-C.   Wang William   Zhu Xiuling   Chan Kenny  

      摘要 + 此论文可免费阅读 (可能需要登录)

Past research has demonstrated that a sampled phase-only hologram (SPOH) is capable of representing an image without the magnitude component of the hologram. At present, a SPOH can only record and reconstruct a single source image. In this paper we propose, for the first time, a method for representing multiple images with a single integrated SPOH (ISPOH). Subsequently, each image can be retrieved from the ISPOH with a unique key parameter, and displayed as a visible image on a phase-only spatial light modulator.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

Wang Haoyu   Zheng Jun   Fu Yifei   Wang Chengliang   Huang Xinran   Ye Zhicheng   Qian Liejia  

      摘要 + 此论文可免费阅读 (可能需要登录)

Separating lights into different paths according to the polarization states while keeping respective path's polarizations with high purification is keen for polarization multiplex (PMX) in optical communications. Metallic nanowire gratings (MNGs) with multi-slits in a period are proposed to achieve polarized beam splitters (PBSs) in reflection and diffraction. The setting of multi-slits largely reduces the reflection of photons with transverse magnetific field (TM) via plasmonic waveguiding effect, which leads to highly polarized output lights with extinction ratio (ETR) larger than 20 dB in each channel. The proposed reflection/diffraction PBSs enrich the approaches to control the polarization states with the advantages of wide incident angles and flexible beam splitting angles.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

Cheng Ju   Zhang Jia   陆 建   Bian Xintian   Zhang Hongchao   Shen Zhonghua   Ni Xiaowu   Ma Pengcheng   Shi Jin  

      摘要 + 此论文可免费阅读 (可能需要登录)

The apatite compound Ca4La6(SiO4)4(PO4)2O2 (CLSPO) was explored as the host material for phosphors used in white light-emitting diodes (wLEDs). The crystal structure of the CLSPO host prepared by the solid-state reaction method was investigated with Rietveld refinement. The Rare-earth ions (Eu3+/ Tb3+/Ce3+, Tb3+/Tb3+, Mn2+) activated CLSPO phosphors were synthesized and their photoluminescence properties, quantum yields as well as thermal stabilities were studied. Under near-ultraviolet excitations, the Eu3+ and Tb3+ doped CLSPO compounds exhibited red and green emissions with high luminescence efficiencies. Besides, tunable emissions from green to orange were obtained by introducing Mn2+ ions into the Tb3+ doped CLSPO samples. The results showed the phosphors studied may have potential applications for wLEDs.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

Shisong Wu   Yuanyang Li  

      摘要 + 此论文可免费阅读 (可能需要登录)

A 1550-nm all-fiber pulsed laser Doppler vibrometer (LDV) based on time-domain chopping (TDC) techniques is developed to overcome demodulation failures caused by multipath interference. The system adopts an adjustable configuration on pulse duration and pulse repetition frequency according to the distance. An experiment is carried out at a 25 m standoff with a pulse duration of 80 ns, single pulse energy of 0.4 nJ, and pulse repetition frequency of 1 MHz. A waveform and spectrogram of the demodulated voice show that the pulsed LDV system has a good performance in long-range voice listening.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

Zhang Quan   Yu Junjie   Shi Biran   Tang Fanchun   Li Jianlang  

      摘要 + 此论文可免费阅读 (可能需要登录)

The excitation of high-order Laguerre-Gaussian mode in a Nd:YAG laser resonator was presented by applying the diffraction of a second-order circular Dammann grating (CDG) for annular pumping. In the study, the 808-nm pump light was shaped into double-ring structure by the CDG and matched spatially with that of an ideal LG11 mode. As a result, the laser resonator generated LG11 vortex mode, and the laser power reached 204 mW with 14.5-% slope efficiency. Also, when the cavity mirror was tilted, the laser output could switch to LG01 vortex mode. The results showed the convenience and versatility of CDG in annular-pumped vortex laser.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

Sun Licheng   Liu Tinghao   Fu Xing   Guo Yading   Wang Xiaojun   Shao Chongfeng   Zheng Yamin   Sun Chuang   Lin Shibing   Huang Lei  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this letter, a 116-actuator deformable mirror (DM) was used to correct the wavefront distortion in a 10.7 J, 10 Hz Nd:YAG slab amplifier. By applying a pump-light homogenizer to transform the 3×1 near-field beam array into an integrated beam, the beam quality was greatly improved from 5.54 times diffraction limited (TDL) to 1.57 TDL after being corrected by the DM. To the best of our knowledge, this is the first investigation on the beam quality control of an arrayed near-field beam in the high-energy diode-pumped solid-state lasers.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

Han Xiao-Chuan   Feng Lantian   li yuxuan   Zhang LanXuan   Zhang Yongsheng   Song Junfeng  

      摘要 + 此论文可免费阅读 (可能需要登录)

The continuous-time quantum walk (CTQW) is the quantum analogue of the continuous-time classical walk (CTCW), and is widely used in universal quantum computations. Here, taking the advantages of the waveguide arrays, we implement large-scale CTQWs on chips. We couple the single-photon source into the middle port of the waveguide arrays and measure the emergent photon number distributions by utilizing the fiber coupling platform. Subsequently, we simulate the photon number distributions of the waveguide arrays by considering the boundary conditions. The boundary conditions are quite necessary in solving the problems of quantum mazes.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

Adzir Mahdi Mohd   Kuen Yao Lau   Pin Jern Ker   Abas Ahmad Fauzi   Alresheedi Mohammed Thamer  

      摘要 + 此论文可免费阅读 (可能需要登录)

Saturable absorber is commonly employed to generate ultrashort laser with mode-locking scheme. In an erbium-doped fiber laser system, the laser regimes either 1530 nm or 1550 nm wavelength are procured based on the absorption profile of the erbium-doped fiber. The absorption of erbium-doped fiber is designed to emit at both wavelengths by control the net gain of the laser cavity. Subsequently, simultaneous erbium-doped fiber laser emission is attained at 1533.5 nm and 1555.1 nm with the pulse duration of 910 fs and 850 fs, respectively. Therefore, this work maximizes the output portfolios of mode-locking fiber laser for dual-wavelength ultrashort pulses emission.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

cao zhen   He Hongbo   Hu Guohang   Zhao Yuanan   Yang Liujiang   Shao Jianda  

      摘要 + 此论文可免费阅读 (可能需要登录)

A time-resolved high-power laser photometer, which measures the real-time variations of transmission, internal reflection, and scattering simultaneously with picosecond time resolution, was developed to investigate the material response sequence during high-power nanosecond laser irradiation in thick fused silica. It was found that the transient transmission decreased sharply accompanied with an increase in internal reflection at the rising edge of the laser pulse. The transient transmission recovered while laser damage did not occur, but it did not recover if the scattering increased, indicating the occurrence of laser damage. The reason of sharp-decrease of transmission and the relationship between the transmission drop and laser damage were discussed.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

zhang jingang   Nie Yunfeng   Fu Q.   Peng Yifan   Xiang Libin  

      摘要 + 此论文可免费阅读 (可能需要登录)

Conventional optical system design employs combinations of different lenses to combat aberrations, which usually leads to considerable volume and weight. In this paper, a tailored design scheme that exploits state-of-the-art digital aberration correction algorithms in addition to traditional optics design is investigated. In particular, the proposed method is applied to the design of refractive telescopes by shifting the burden of correcting chromatic aberrations to software. By enforcing cross-channel information transfer in a post-processing step, the uncorrected chromatic aberrations are well mitigated. Accordingly, a telescope of f-8, 1,400mm focal length, and 0.14° field of view is designed with only two lens elements. The image quality of the designed telescope is evaluated by comparing it to the equivalent designs with multiple lenses in a traditional optical design manner, which validates the effectiveness of our design scheme.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

Li Shasha   Shen Baifei   Wang Wenpeng   Bu Zhigang   Zhang Hao   Zhang Hui   Zhai Shuhua  

      摘要 + 此论文可免费阅读 (可能需要登录)

Vortex harmonics with fractional average orbital angular momentum are generated when a relativistic fractional vortex beam incidents on and reflects from an overdense plane plasma target. A two-step model is presented to explain the far-field patterns of the harmonics. In the first step, a fundamental spot-shaped hole is produced during the hole-boring (HB) stage, and harmonics are generated simultaneously. In the second step, different order harmonics are diffracted by the hole and propagate to the far-field. This process can be accurately described by Fraunhofer diffraction theory. This work facilitates a basic recognition of fractional vortex beams.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

Guo Xi   Xing Zhikun   Qin Huabao   Sun Qizhen   Liu Deming   Zhang Lin   Yan Zhijun  

      摘要 + 此论文可免费阅读 (可能需要登录)

We have investigated the whole polarization-extinction-ratio (PER) spectrum and annealing properties of 45°-tilted fiber gratings (45°-TFGs). Experimental results show the PER spectrum of 45°-TFGs is Gaussian-like profile and covers 540nm bandwidth form 1260 to 1800nm, in which the bandwidth with PER greater than 10dB is over 250nm. The output polarization distribution of 45°-TFGs was analyzed by employing a bulk linear polarizer, and the results show a perfect figure “8”, which indicates that the 45°-TFG is a type of linear polarizer. Moreover, the annealing property of 45°-TFGs was measured up to 700 ℃, in which the PER of grating started to decrease at 300℃ and reached to the minimum at 700℃. Based on these results, the 45°-TFGs can be used as ultra-wide bandwidth in-fiber polarizing devices.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

Shi Nuannuan   Li Wei   Zhu Ninghua   Li Ming  

      摘要 + 此论文可免费阅读 (可能需要登录)

To overcome the beam squint in wide instantaneous frequency, we review a number of system level optical controlled phase array antenna (OCPAA) for beam forming. The optical delay network based on fiber device in terms of topological structure of N-bit optical switch, fiber grating, high-dispersion fiber, vector-sum technology is discussed, respectively. At last, integrated circuit is simply summarized.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

SHAO DIXIANG   Chen Yao   Zhou T.   Zhang R.   FU ZHANGLONG   Zhuang Songlin   Cao Juncheng  

      摘要 + 此论文可免费阅读 (可能需要登录)

Optical frequency combs, which are generated by the cascade of a phase modulator and a Mach-Zehnder intensity modulator, are used as a polychromatic signal source in the terahertz imaging system to improve imaging quality. Interference effect caused by the monochromatic wave has been greatly suppressed. The required optical power in the presented system is as low as ~30% of that in the system using the Er-doped fiber amplifier as source, which can reduce cost and protect photodiodes from damage. This work provides an effective, low power consumption, low cost, and easy way to realize terahertz imaging with high quality, and can be used in the future security inspection.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Yan Dongyu   Liu Bowen   Chu Yuxi   Song Huanyu   Chai Lu   Hu Minglie   Wang Qingyue  

      摘要 + 此论文可免费阅读 (可能需要登录)

We report a hybrid femtosecond laser system based on a femtosecond Yb-doped fiber laser and an Yb:KGW regenerative amplifier. To match the central wavelength of the seed source, an Yb:KGW crystal is used in the regenerative amplifier for Np-polarization. We study and optimize the dynamics of nonlinear amplification to alleviate the gain narrowing effect. With optimization, the system can output 270-fs pulses with 21-μJ pulse energy at a 60-kHz repetition rate.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Zhan Yueying   He Jianhua   Wang Fei   Wang Liqian  

      摘要 + 此论文可免费阅读 (可能需要登录)

In our paper, we selected several commercial optical transceivers, which consist of single-channel transceiver modules, parallel transmitting and receiving modules, and EPON OLT and ONU modules, to do the total ionizing dose (TID) testing via gamma-ray radiation method. The changing of current and receiver sensitivity of optical transceivers are discussed and analyzed. Based on the TID testing exposed to a total ionizing dose of 50 krad (Si) at a dose rate of about 0.1 rad (Si)/s, the performance of single-channel transceivers and parallel receiving modules have not changed after 50 krad (Si) exposed, the parallel transmitting and EPON ONU modules have not worked after 40 krad (Si) and 47 krad (Si) exposed, the EPON OLT module has bit error in the process of irradiation and it can work well after annealing, and the reason for the error of OLT is analyzed. Finally, based on the theoretical analyzed and testing results, this paper provides several design suggestions to improve the reliability for optical transceivers, which can be referenced by satellite system designation for various space missions.

       PDF全文        Chinese Optics Letters ，2019年第17卷第5期 pp.05      

zhang yanjun   Li Yunchao   Hu Xuwen   Zhang Lu   Liu Zhaojun   Zhang Kaifang   Mou Shihao   Zhang Shougang   Yan Shu-Bin  

      摘要 + 此论文可免费阅读 (可能需要登录)

As the key part of chip-scale atomic clocks (CSACs), the vapor cell directly determines the volume stability and power consumption of the CSAC. The reduction of the power consumption and CSAC volumes demands the manufacture of corresponding vapor cells. However, their micro-fabrication is challenging. This overview presents the research development of vapor cells of the past few years and analyzes the shortages of the current preparation technology. By comparing several different vapor cell preparation methods, we successfully realized the micro-fabrication of vapor cells using anodic bonding and deep silicon etching. The microelectromechanical system (MEMS) fabrication process is presented in detail. It is simple and avoids weak bonding strengths caused by alkali metal volatilization during anodic bonding under high temperatures. Finally, the vapor cell D2 line was characterized via optical absorption resonance. According to the results, the proposed method is suitable for CSAC.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Sun Han   wang Lan   Zhang Yaxin   Liang Shixiong   Han Jiaguang   Lan Feng   Zhou Xinlan   Yang Ziqiang  

      摘要 + 此论文可免费阅读 (可能需要登录)

This paper presents a double layer structure combined with cracked cross meta-surface and grating surface to realize arbitrary incident linear THz wave polarization conversion. The arbitrary incident linear polarization THz wave will be induced the same resonant modes in the unit-cell, which results in polarization conversion insensitive to the linear polarized angel. Moreover, the zigzag-shaped resonant surface current leads to a strong magnetic resonance between the meta-surface and gratings, which enhanced the conversion efficiency. The experimental results show more than 70% conversion rate can be achieved under arbitrary linear polarized within a wide frequency band. Moreover, around 0.89THz nearly perfect polarization conversion is realized.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Li Hui   Zhao Qingchao   Jiang Shaodong   Ni Jiasheng   Wang Chang  

      摘要 + 此论文可免费阅读 (可能需要登录)

A fiber Bragg grating (FBG) and Fabry-Perot (FP) cavity cascaded fiber sensing system was manufactured for temperature and pressure sensing. Temperature high up to 175 ℃ sensing was performed by FBG for the linear variation of FBG wavelength with temperature. After temperature was sensed, the demodulation system can find the original FP cavity length and its pressure-cavity length correlation coefficient, thus the ambient pressure would be calculated. The sensing pressure can be as high as 100 MPa with a repeatability of 1/10000 and high stability. This kind of fiber sensor has been used in Shengli Oil Field.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Gong Dejing   Yuan Yinquan   Liang Lei   Yang Minghong  

      摘要 + 此论文可免费阅读 (可能需要登录)

Using theoretical simulations for optical fiber surface plasmon resonance (SPR) sensor and prism based SPR sensor coated with negative permittivity material (NPM), we investigated the effect of the permittivity of NPM on the transmitted spectrum of optical fiber SPR sensor and the reflected spectrum of prism based SPR sensor, and then obtained optimum permittivity of the NPM which can excite the sharpest SPR spectrum in white light region (400-900 nm).

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Shahzadi Mahnoor   Zhang W. L.   Talha Muhammad  

      摘要 + 此论文可免费阅读 (可能需要登录)

Exciton-polaritons offer an exceptional platform for future photoelectronic and quantum information applications. The influence of optical Stark effect on exciton-polariton in microcavity embodied with a monolayer WS2 is studied. A polarization dependent model is proposed to study the change of strongly coupled excitons and photons in WS2 microcavity. It is revealed through both steady and dynamical states analysis that an outside optical Stark pulse can effectively vary the polariton characteristics such as dispersion, exciton and photon fractions through blue shifting of excitonic resonance. Thus, the analysis and control of excitons-polaritons in a WS2 microcavity via spin-selective trigger could be achievable.

       PDF全文        Chinese Optics Letters ，2019年第17卷第2期 pp.02      

Ma Yuxuan   Meng Fei   Wang Yan   Wang Aimin   Zhang Zhigang  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate a 0.95 GHz repetition rate fully stabilized Yb:fiber frequency comb without optical amplification. Benefitted from the high mode power and high coherence, this comb achieved 35 dB to 42 dB signal to noise ratio on the direct heterodyne beat signals with at least 6 continuous wave lasers (at 580nm, 679nm, 698nm, 707nm, 813nm and 922 nm) while keeping >40 dB carrier envelop frequency signal. It can be used for the direct measurement of optical frequencies in visible and near-infrared wavelengths, and has a great potential on simultaneous comparison of multiple optical frequencies.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Qian Qizhang   Wang Nan   Zhao Shengzhi   Li Guiqiu   Li Tao   Li Dechun   Yang Kejian   Zang Jie   Ma Houyi  

      摘要 + 此论文可免费阅读 (可能需要登录)

Gold nanorods (GNRs) with two different aspect ratios were successfully utilized as saturable absorbers (SAs) in passively Q-switched Nd:LLF laser emitting at 1.34 μm. Based on the GNRs with an aspect ratio of 5, a maximum output power of 1.432 W was achieved, and the narrowest pulse width was 328 ns with a repetition rate of 200 kHz. But in the case of the GNRs with the aspect ratio of 8, a maximum output power of 1.247 W was achieved, and the narrowest pulse width was 271 ns with a repetition rate of 218 kHz. Our experimental results reveal that the aspect ratios of GNRs have different saturable absorption effects at a specific wavelength. In other words, for passively Q-switched lasers at a given wavelength, we are able to select the most suitable GNRs as an SA by changing their aspect ratio.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Li Zhuang   lv xiaoyi  

      摘要 + 此论文可免费阅读 (可能需要登录)

Echinococcosis—a parasitic disease caused by Echinococcus granulosus or Echinococcus multilocularis larvae—occurs in many regions in the world. This disease can pose a serious threat to public health and thus requires a convenient and cost-effective method for early detection. So we developed a novel method based on visual saliency and scale-invariant features, that detects the tapeworm parasites .This method improves upon existing bottom-up computational saliency models by introducing a visual attention mechanism. The results indicated that the proposed method offers a higher level of both accuracy and computational efficiency when detecting Echinococcus granulosus protoscoleces, which in turn could improve early detection of echinococcosis.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Xiong Baoxing   Gao Fan   Zhang Xiang   Yuan Xiao  

      摘要 + 此论文可免费阅读 (可能需要登录)

The two-dimensional angular filter based on volume Bragg gratings in photothermorefractive glass for ns laser pulse is demonstrated. The experimental results show that the near-field beam quality of laser pulse was effectively improved. The near-field modulation and contrast ratio were improved 1.75 and 4.48 times, respectively. The PSD curves showed that the spatial frequencies more than 0.9mm-1 in x direction and 1.2mm-1 in y direction were effectively suppressed.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

YAN Xu   郭 立新   Chen Minjian   Chai Shuirong  

      摘要 + 此论文可免费阅读 (可能需要登录)

Vortex splitting is one of the main causes of instability in orbital angular momentum (OAM) modes transmission. Recent advances in OAM modes free-space propagation have demonstrated that abruptly autofocusing Airy vortex beams (AAVBs) can potentially mitigate the vortex splitting effect. However, different modes of vortex embedding will affect the intensity gradients of the background beams, leading to changes in the propagation characteristics of vortex beams. This study presents the unification of two common methods of coupling autofocusing Airy beams with vortices by introducing a parameter (m) which also controls the intensity gradients and focusing properties of the AAVBs. We demonstrate that vortex splitting can be effectively reduced by selecting an appropriate value of the parameter (m) according to different turbulence conditions. In this manner, the performance of OAM-based free-space optical (FSO) systems can be improved.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Cao Yun   Xiong Jichuan   Liu Xuefeng   Xia Zhiying   Wang Weize   Yadav N.P.   Liu Weiping  

      摘要 + 此论文可免费阅读 (可能需要登录)

This paper tackles the issue of non-contact detection of ultrasonic fields by utilizing a novel optical method based on the parametric indirect microscopic imaging (PIMI) technique. A general theoretical model describing the three-dimensional anisotropic photoelastic effect in solid was developed. The mechanism of polarization status variations of light passing through the stress and strain fields was analyzed. Non-contact measurements of ultrasonic field propagating in an isotropic quartz glass have been fulfilled using the PIMI technique under different ultrasonic excitation conditions. PIMI parameters such as sinδ, Φ and the Stokes parameters have been found sensitive to ultrasonic fields.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Liu kai   Wei Qi   Huang Yongqing   Duan Xiaofeng   Wang Qi   Ren Xiaomin   Cai Shiwei  

      摘要 + 此论文可免费阅读 (可能需要登录)

An integrated optoelectronic chip pair which can transmit and receive optical signals simultaneously are proposed in this paper. The design and optimization of its key structure, the VCSEL's DBR, is presented. Analysis is also done for its influence on the integrated chip's performance. Moreover, the chip pair's performance under dynamic conditions are analyzed. Their 3 dB modulation bandwidths are higher than 10 GHz and their 3 dB photo-response bandwidths are around 23 GHz. Their applications will further improve the performances of the optical interconnects

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Zhu Lida   Wang Yi   Yuan Yi   Zhou Hongxian   Zhao Yuqian   Ma Zhenhe  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrated a method for CCT measurement with a sub-micrometer sensitivity using a spectral domain optical coherence tomography (SD-OCT) system without needing a super broad bandwidth light source. By combining the frequency and phase components of Fourier transform (FT), the method is capable of measurement of a large dynamic range with a high sensitivity. Absolute phases are retrieved by comparing the correlations between the detected and simulated interference fringes. The phase unwrapping ability of the present method was quantitatively tested by measuring the displacement of a piezo linear stage. The human CCTs of six volunteers were measured to verify its clinical application. It provides a potential tool for clinical diagnosis and research applications in ophthalmology.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

chen minghui   jia wenyu   he jintao   geiser martial   zheng gang  

      摘要 + 此论文可免费阅读 (可能需要登录)

This study introduced the research into, and development of, a portable, miniaturised system for the measurement of the refractive index of sub-microlitre liquid based on a microfluidic chip. A technical method, namely, double-beam interference, was proposed for use in the measurement. Based on this, by using a laser diode as a light source, changes in refractive index were calculated by utilising a complementary metal-oxide-semiconductor (CMOS) to detect the movement of interference fringes of the liquid. Firstly, this study simulated the effects of influencing factors on the interference infringes of two Gaussian beams, such as their spot sizes, distance between two beam spots, and detection range. Secondly, this research introduced the system design and construction of the double-beam interference method and analysed the results of refractive index tests on sub-microlitre aqueous glucose solutions with different concentrations therewith. The measurement accuracy reached 10-4 RIU. This system has a compact structure and is rendered portable by using batteries for its power supply. The entire system is designed to be a double Z-shaped structure with a length of about 15 cm, a width of 5 cm, and height of about 10 cm: it can be used to measure changes in refractive index of sub-microlitre to nanolitre liquids based on the use of a microfluidic chip.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Guo Yujian   Alkhazragi Omar   Kang Chun   SHEN CHAO   Mao Yuan   Sun Xiaobin   Ng Tien   Ooi B. S.  

      摘要 + 此论文可免费阅读 (可能需要登录)

This tutorial focuses on devices and technologies that are part of laser-based visible light communication (VLC) systems. Laser-based VLC systems have advantages over their light-emitting-diode-based counterparts, including having high transmission speed and long transmission distance. We summarize terminologies related to laser-based solid-state lighting and VLC, and further review the advances in device design and performance. The high-speed modulation characteristics of laser diodes and superluminescent diodes, the on-chip integration of optoelectronic components in the visible color regime, such as the high-speed integrated photodetector, were introduced. The modulation technology for laser-based white light communication systems, and the challenges for future development were then discussed.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Chen Menglin   Luo Zhijun   Liu Yanan   Gan Zongsong  

      摘要 + 此论文可免费阅读 (可能需要登录)

Fractional density of states (FDOS) hinders the accurate measuring of the overall spontaneous emission (SE) control ability of a three-dimensional (3D) photonic crystal (PC) with the current widely used SE decay lifetime measurement systems. Based on analyzing the FDOS property of a 3D PC from theory and simulation, the excitation focal spot position averaged FDOS with a distribution broadening parameter were proposed to accurately reflect the overall SE control ability of the 3D PC. Experimental work was done to confirm that our proposal is effective which can contribute to comprehensively characterize the SE control performance of photonic devices with quantified parameters.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Yan Wen   Yao Yuan   Sun Yuxin   Hoyt Chad   Jiang Yanyi   Ma Longsheng  

      摘要 + 此论文可免费阅读 (可能需要登录)

We study a Zeeman slower using the magnetic field generated by a coil pair for a magneto-optical trap. The efficiency of the Zeeman slower is shown to be dependent on the intensity and the frequency detuning of the laser light for slowing the atoms. With the help of numerical analysis, optimal experimental parameters are explored. Experimentally, the optimal frequency detuning and intensity of the slowing beam are explored, and 4.2 × 107 ytterbium atoms are trapped in the magneto-optical trap.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Ge Aichen   Liu Bowen   Chen Wei   Tian Haochen   Song Youjian   Chai Lu   Hu Minglie  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate a coherent synthesis system based on femtosecond Yb-doped fiber laser technology. The output pulse of the amplification system is divided into two replicas, and seeded into photonic crystal fibers of two parallel branches for nonlinear pulse compression. Because of the different nonlinear dynamics in the photonic crystal fibers, the compressed pules show different spectra which can be spliced to form a broad coherent spectrum. The integrated timing jitter between the pulses of two branches is less than one tenth of an optical cycle. By coherently synthesizing pulses from these two branches, 8-fs few-cycle pulses are produced.

       PDF全文        Chinese Optics Letters ，2019年第17卷第4期 pp.04      

Shang Jimin   Zhang Shuai   Wang Yongqiang   Wen Hongyu   Wei Zhongming  

      摘要 + 此论文可免费阅读 (可能需要登录)

The electronic and optical properties of the ZrS2/SnS2 van der Waals heterostructure have been investigated. We find out the formed heterostructure has an intrinsic type-I band alignment. Moreover, the characteristics of optical absorption in heterostructure can be enhanced to the amount of 10^6 in ultraviolet light region. In addition, the tuning electronic properties of ZrS2/SnS2 heterostructure are very interesting, due to the transitions from type-I to type-II band alignment can be occurred by applying an external electric field. These results suggest that the atomically thin materials ZrS2/SnS2 heterostructure will be utilized for the flexible optoelectronic applications.

       PDF全文        Chinese Optics Letters ，2019年第17卷第2期 pp.02      

wang taijin   wang jiang   Wang Yonggang   yang xiguang   liu sicong   lv ruidong   Chen Zhendong  

      摘要 + 此论文可免费阅读 (可能需要登录)

A single output Q-switched Nd: GdVO4 laser with a reflective graphene oxide (GO) saturable absorber was demonstrated. The shortest pulse duration in Q-switched laser is 115 ns and the output power ranges from 1.23 W at 1.71 MHz to 2.11 W at 2.50 MHz when the pump power rises from 7.40 W to 10.90 W, with the utilization of GO Langmuir-Blodgett (LB) films based on the convenient and low-cost LB technique. To the best of our knowledge, It’s the highest output power in Q-switched laser with GO saturable absorber.

       PDF全文        Chinese Optics Letters ，2019年第17卷第2期 pp.02      

Yang Huashan   Zhang Fuling   Leng Lemeng   Zeng Zhaobang   Shao Yue   Zhang Hui   Yang Nan   Chen Xiangning  

      摘要 + 此论文可免费阅读 (可能需要登录)

A simple method improving grating couplers’ coupling efficiency without any extra micro fabrication processes is proposed. This method can improve the coupling efficiency with 1.69dB by utilizing the combined interference in cladding layer and air gap between the cladding surface and the paralleled angle polished fiber facet. The proposed method can be applied to various kinds of on-chip grating couplers. Back reflection, 1-dB bandwidth and fiber alignment tolerance has been also improved at the same time.

       PDF全文        Chinese Optics Letters ，2019年第17卷第3期 pp.03      

Wang Hua   Du Tuanjie   Li Yanhong   Zou Jinhai   Wang Kaijie   Zheng Fuyong   Fu Junfeng   Yang Jihai   Fu Hongyan   Luo Zhengqian  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrated a 2080 nm long-wavelength mode-locked Tm-doped fiber laser operating in the dissipative soliton resonance (DSR) regime. The compact all-fiber dumbbell-shaped laser is simply constructed by a 50/50 fiber loop mirror (FLM), a 10/90 FLM and a piece of large-gain Tm-doped double-clad fiber pumped by a 793 nm laser diode. The 10/90 FLM is not only used as an output mirror, but also acts as a periodical saturable absorber for initiating DSR mode locking. The stable DSR pulses are generated at the center wavelength as long as 2080.4 nm, and the pulse duration can be tunable from 780 ps to 3240 ps as the pump power is increased. The maximum average output power is 1.27 W, corresponding to a pulse energy of 290 nJ and a nearly constant peak power of 93 W. This is, to the best of our knowledge, the longest wavelength for DSR operation in mode-locked fiber laser.

       PDF全文        Chinese Optics Letters ，2019年第17卷第3期 pp.03      

shan chong   Zhao Yuanan   Gao Yanqi   Zhao Xiaohui   Hu Guohang   Ma Weixin   Shao Jianda  

      摘要 + 此论文可免费阅读 (可能需要登录)

The spatial resolved method, which measures the laser-induced damage fluence by identifying the location of damage point at the Gaussian beam three-dimensional direction, is demonstrated. The advantages and practicality of this method has been explained. Taking a triple frequency beam splitter as an example, the defect damage fluence can be calculated by the spatial resolved method accurately. The different defect damage performance of the triple frequency splitter was distinguished under irradiations of 355nm laser only and 532nm laser only. The spatial resolved method provides a way to obtain precise information of optical film defect information.

       PDF全文        Chinese Optics Letters ，2019年第17卷第3期 pp.03      

Zhao Junhao   Xiao Gang   Zhang Xingchen   Bavirisetti Durga Prasad  

      摘要 + 此论文可免费阅读 (可能需要登录)

By improving the long-term correlation tracking algorithm (LCT), an effective object tracking method (ILCT) is proposed to address the issue of occlusion. If the object is judged being occluded by the designed criterion, which is based on the characteristic of response value curve, an added re-detector will perform re-detection and the tracker is ordered to stop. Besides, a filtering and adoption strategy of re-detection results is given to choose the most reliable one for the re-initialization of the tracker. Extensive experiments are carried out under the conditions of occlusion and the results demonstrate that ILCT outperforms some state-of-the-art methods in terms of accuracy and robustness.

       PDF全文        Chinese Optics Letters ，2019年第17卷第3期 pp.03      

Zhao Yanting   Song Zixuan  

      摘要 + 此论文可免费阅读 (可能需要登录)

We report the observation of ultralow-power absorption saturation in a tapered optical nanofiber（TOF）mounted in a hot cesium vapor in a vacuum chamber. The small optical mode area of TOF produces a great influence on optical properties, allowing optical interactions with nanowatt-level power. The comparison of transmission characteristic for the TOF system and free-space vapor is investigated at different input power and atomic density. The unique performance of the Cs-TOF system makes it promising candidate in resonant nonlinear optical applications with ultralow power.

       PDF全文        Chinese Optics Letters ，2019年第17卷第3期 pp.03      

liu mengli   Yuyi Ouyang   Hou Huanran   Liu Wenjun   Wei Zhiyi  

      摘要 + 此论文可免费阅读 (可能需要登录)

Compared with the extensively studied MoS2 and WS2, tungsten telluride (WTe2) owns smaller bandgap, which is applicable to near-infrared system in photodetectors, communications and ultrafast optic. In this work, the WTe2 SA with the tapered fiber structure is prepared by the magnetron-sputtering technology, which enable the prepared SA to be low in cost and has strong nonlinearity. The modulation depth of prepared WTe2 SA is measured as 31.06%. The Q-switched fiber laser operating at 1.5 μm is successfully investigated by incorporating the proposed SA into the prepared ring cavity. As far as we know, this is the first attempt of WTe2 in the Q-switched fiber laser at 1.5 μm yet.

       PDF全文        Chinese Optics Letters ，2019年第17卷第2期 pp.02      

Jiang Leyong   Tang Jiao   Wang Qingkai   Wu Yuexiang   Zheng Zhiwei   xiang yuanjiang   Dai Xiaoyu