Liu Kexuan   He Zehao   Cao Liangcai  

      摘要 + 此论文可免费阅读 (可能需要登录)

The bidirectional error diffusion (BERD) algorithm is free from random phase modulation that introduces speckle noise on the reconstructed images, compared with other computer-generated phase-only hologram (POH) approaches. During the POH generation process, the amplitudes of all pixels are traditionally set to one for diffusing the errors to their neighborhood unprocessed pixels. In this paper, we reveal that the reconstruction quality depends on the uniform amplitude value for different object pattern. The pattern-adaptive bidirectional error diffusion (PA-BERD) algorithm is proposed for high-quality holographic reconstruction. The optimized amplitude value can be acquired for each object pattern and each propagation distance. The PA-BERD based POHs have shown higher reconstruction quality than traditional BERD based POHs in simulations as well as optical experiments.

       PDF全文        Chinese Optics Letters ，2021年第19卷第5期 pp.05      

jiang zengshun   An Xingqi   Zhang Yuqin   Liu Xuan   Qin Xifeng   Zhao Yanjie   Wang Huilin   Liu Guiyuan   song hongsheng  

      摘要 + 此论文可免费阅读 (可能需要登录)

After the 3D self-affine fractal random surface simulated, we use the optical scattering theory to calculate the deep Fresnel region speckle (DFRS) under considering the more strict shadowing effect. The evolution of DFRS with the scattering distance and the intensity probability distribution were studied. It is found that the morphology of the scatterer has an antisymmetric relationship with the intensity distribution of DFRS, and the effect of micro-lenses on the scattering surface causes the intensity probability distribution of DFRS to deviate from the Gaussian speckle in the high light intensity area.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

Zhao Yuqing   Wang Qiangguo   Meng Lihua   Yao Yongping   Liu Shande   Cui Na   su liangbi   Zheng Lihe   Zhang Huiyun   Zhang Yuping  

      摘要 + 此论文可免费阅读 (可能需要登录)

The anisotropy of thermal property in Yb,Nd:Sc₂SiO₅ crystal are investigated from the temperature of 293 to 573 K. Based on the systematical study of thermal expansion, thermal diffusivity and specific heat, the thermal conductivity in Yb,Nd:Sc₂SiO₅ crystal orientated at (100), (010), (001) and (406) is calculated to be 3.46, 2.60, 3.35 and 3.68 W/(m·K), respectively. The laser output anisotropy of continuous-wave (CW) and tunable laser are characterized, accordingly. A maximum output power of 6.09 W is achieved in Yb,Nd:Sc₂SiO₅ crystal with (010) direction, corresponding to a slope efficiency of 48.56 %. The tuning wavelength ranges in Yb,Nd:Sc₂SiO₅ crystal orientated at (100), (010) and (001) is 68, 67 and 65 nm, separately. The effects of thermal properties on CW laser performance are discussed.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

Qiu Feng   Han Yu  

      摘要 + 此论文可免费阅读 (可能需要登录)

Electro-optic (EO) ring resonator modulators have a number of telecommunications and scientific applications, including analog optical links, optical signal processing, and frequency comb generation. Among the EO materials used to fabricate ring modulators, EO polymer has many promising characteristics, including a high EO coefficient of 100-200 pm/V (3-7 times larger than that of LiNbO3), an ultrafast EO response time (<10 fs), a low dielectric constant (3 to 4) with very little dispersion up to at least 250 GHz and a straightforward spin-coating fabrication process. These inherent characteristics will be able to combine excellent EO properties with simple processing to achieve exceptional performance in a variety of high-speed optical modulation and sensing devices. This review focuses on the research and recent development of the ring resonator modulators based on EO polymer. The first part describes the operation principle of EO ring resonator modulators, such as modulation mechanism, EO tunability and 3-dB bandwidth. Subsequently, the emphasis is placed on the discussion of the ring modulators with EO polymer as the waveguide core and the improvement of EO modulation by using EO polymer / titanium dioxide hybrid core. At the end, a series of EO polymer on silicon platforms including slot modulators, etching-free modulators and athermal modulators are reviewed.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

Shi Qiangshi   Shi Qiangshi   Jin Xia   Wu Qiannan   Huang Cheng   Sun Baoyin   Gao Lei   Xu Yadong   Fu Yangyang  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this work, inspired by advances in twisted two dimensional materials, we design and study a new type of optical bi-layer metasurface system, each based on subwavelength metal slit arrays with phase gradient modulation, referred as metagratings (MG). It is shown that due to the found reversed diffraction law, the interlayer interaction that can be simply adjusted by the gap size, can produce a transition from optical beam splitting to high-efficiency asymmetric transmission of incident light from two opposite directions. Our results provide new physics and some advantages for designing subwavelength optical devices to realize efficient wavefront manipulation and one-way propagation.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

Cao Jiayuan   Li Na   Bai Ya   Liu Peng   Li Ruxin  

      摘要 + 此论文可免费阅读 (可能需要登录)

We present a velocity-gauge model for the generation of even-order high harmonics, and reveal that the even-order harmonics originate from the multiple-step transitions among the energy bands in momentum space, while the odd-order harmonics mainly from the direct transitions. The lower valence band is found vital for the generation of even harmonics. Relative intensity of even-order harmonics versus the odd orders is calculated and shows a growing trend as the laser field amplitude increases.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

Li Siqiao   Zhang Tiantian   Qiao Yaojun   Zhou Ji  

      摘要 + 此论文可免费阅读 (可能需要登录)

This paper proposed a hybrid layered asymmetrically clipped optical single-carrier frequency-division multiplexing (HLACO-SCFDM) scheme for dimmable visible light communication. It designs a signal structure that combines LACO-SCFDM and negative LACO-SCFDM in proportion for improving the inherent weaknesses of orthogonal frequency division multiplexing (OFDM)-based dimmable schemes and further enhancing the system performance. Compared to HLACO-OFDM-based dimming scheme, it obtains lower bit error ratio and enables efficient communication over broader dimming range. Its spectral efficiency realizes 2.875 bit/s/Hz within the dimming range of 30%-70%, and the attainable average spectral efficiency gains exceed at least 19.21% compared to other traditional dimmable schemes.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

Meng Fangyuan   Yu Hongyan   Zhou Xuliang   Li Yajie   Wang Mengqi   Yang Wenyu   Chen Weixi   Zhang Yejin   Pan Jiaoqing  

      摘要 + 此论文可免费阅读 (可能需要登录)

Gas sensing for measurement of gas component, concentrations and other parameters plays an important role in many fields. In this letter, a micro-ring resonator laser used for gas sensing is experimentally demonstrated. The multi-quantum-wells micro-ring laser based on whispering-gallery modes (WGMs) with an annular resonator and an output waveguide was fabricated. A single-mode laser with a wavelength of 1746.4 nm was fabricated for the first time experimentally. The output power of 1.65 mW under 40 mA injection current was obtained with a side-mode suppression ratio (SMSR) over 33 dB.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

Zhu Yihuai   Zheng Zhijian   Ge Xiaogang   Du Geguo   Ruan Shuangchen   Guo Chunyu   Yan Peiguang   Hua Ping   Xia Linzhong   Lue Qitao  

      摘要 + 此论文可免费阅读 (可能需要登录)

We experimentally demonstrate an all-fiber supercontinuum source that covers the spectral region ranging from visible to mid-infrared. The ultra-broadband supercontinuum is realized by pumping cascaded photonic crystal fiber and highly-nonlinear fiber with a 1/1.5 μm dual-band pump source. A maximum output power of 9.01 W is achieved using the system, which is the highest power ever achieved from a supercontinuum source spanning from visible to mid-infrared.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

Pan Long   Deng Chenjin   yu cuiping   yue shuai   Gong Wenlin   Han Shensheng  

      摘要 + 此论文可免费阅读 (可能需要登录)

The influence of the sparsity of random speckle illumination on traditional ghost imaging (GI) and ghost imaging via sparse constrains (GISC) in noise environment is investigated. The experiments demonstrate that both GI and GISC obtain their best imaging quality when the sparsity of random speckle illumination is 0.5, which is also explained by some parameters such as detection signal to noise ratio and mutual coherence of measurement matrix.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

Wang Senyu   Ma Yiwei   Xiaoyang Li   Yi Yang   Sun Cuiting   Lin Jingyu   Chengguo Tong   Li Yuxiang   Geng Tao   Sun weimin   Yuan Libo  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this Letter, we propose and investigate a compact optical fiber sensor which aims to measure the torsion in both amount and direction with high sensitivity. This sensor is configured by a triangular-prism-shaped long-period fiber grating which is fabricated by the high frequency CO2 laser polished method. The unique design of the triangular shaped structure breaks the rotational symmetry of the optical fiber and provides the high sensitivity for torsion measurement. In preliminary experiments, the torsion response of the sensor achieves a good stability and linearity. The torsion sensitivity is 0.54 nm/(rad/m), which renders the proposed structure a high sensitive torsion sensor.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

He Chong   Zhou Cheng   Zhou Qian   Xie Shiyi   Tian Jiajun   Yao Yong  

      摘要 + 此论文可免费阅读 (可能需要登录)

A fiber optic sensor for the simultaneous measurement of strain and temperature is proposed and experimentally demonstrated based on Fabry–Pérot (FP) interference and the antiresonant (AR) mechanism. The sensor was implemented using a single-mode fiber (SMF)–hollow-core fiber (HCF)–SMF structure. A temperature sensitivity of 21.11 pm/°C was achieved by tracing the troughs of the envelope caused by the AR mechanism and a strain sensitivity of 2 pm/με was achieved by detecting the fine fringes caused by the FP cavity. The results indicate that the sensor is stable and reliable.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

Tan Chao   Zhao Linjie   Chen Mingjun   Cheng Jian   Yin Zhaoyang   Liu Qi   Yang Hao   Liao Wei  

      摘要 + 此论文可免费阅读 (可能需要登录)

In order to reveal the evolution mechanism of repaired morphology and the material’s migration mechanism on the crack surface in the process of CO2 laser repairing surface damage of fused silica optics, two multi-physics coupling mathematical models with different scales are developed respectively. The physical problems, such as heat and mass transfer, material phase transition, melt flow, evaporation removal and crack healing, are analyzed. Studies show that material ablation and the gasification recoil pressure accompanying the material splash are the leading factors in forming the Gaussian crater with raised rim feature. The use of low-power laser for a long time can fully melt the material around the crack before healing, which can greatly reduce the size of the residual air layer. Combined with the experimental research, the methods to suppress the negative factors (e.g., raised rim, deposited debris, air bubbles) in CO2 laser repairing process are proposed.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

Wang Kaile   Wen Zengrun   Chen Haowei   lu baole   Bai Jintao  

      摘要 + 此论文可免费阅读 (可能需要登录)

We reported a wavelength-flexible all-polarization-maintaining self-sweeping fiber laser based on the intracavity loss tuning brought by the bent optical fiber. The bidirectional cavity structure achieved the self-sweeping effect due to the appearance of the dynamic grating in the active fiber with spatial hole burning effect. Under this, a section of fiber was bent into a circle for adjusting the loss of the cavity. With a descending diameter of bent fiber circle, the sweeping range moves to the shorter wavelength and covers a wide range from 1055.6 to 1034.6 nm eventually. Both the initial wavelength of self-sweeping regime and the threshold of fiber laser show exponential correlation with the diameter of the circular fiber. Our work provides a compact and low-cost way to achieve the broad wavelength-flexible self-sweeping operation.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

Yu Ye   Song Yiwen   Chen Tao   Wang Huaiqiang   Zhuang Songlin   Cheng Qingqing  

      摘要 + 此论文可免费阅读 (可能需要登录)

The Floquet topological insulators (FTI) have been used to study the dynamic quantum system’s topological features within the band structure. However, it is difficult to directly observe the dynamic modulation of the band structure in FTI. Here, we implemented the dynamic Su-Schrieffer-Heeger (SSH) model in periodically curved waveguides to explore new behaviors in FTI using light field evolutions. By changing the driven frequency, near-field evolutions of light in the high-frequency (HF) curved waveguide array exhibit equivalence with the behaviors in the straight array. Furthermore, at the modest driven frequency, the field evolutions in the system show the boundary propagation, which is related to the topological edge modes. Finally, we hope the curved waveguides may open up profound and applicable possibilities for the further development of Floquet engineering in periodically-driven systems, ranging from condensed matter physics to photonics.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

Gu Jun-Hao   Sun Shuai   Xu Yao-Kun   Lin Huizu   Liu Weitao  

      摘要 + 此论文可免费阅读 (可能需要登录)

Applications of ghost imaging is limited by the requirement on large number of samplings. Based on the observation that the edge area contains more information thus requires larger number of samplings, we propose a feedback ghost imaging strategy, to reduce the number of required samplings. The field of view is gradually concentrated onto the edge area, with the size of illumination speckles getting smaller. Experimentally, images of high quality and resolution are successfully reconstructed with much fewer samplings and linear algorithm.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

Feng Ting   Zhu Yunhao   Xie Yejing   Ta Dean   Yuan Jie   Cheng Qian  

      摘要 + 此论文可免费阅读 (可能需要登录)

This study investigated the feasibility of photoacoustic (PA) imaging of bone and characterization of bone features. By conducting the experiments on the bovine femoral heads ex vivo, the light and ultrasonic penetration in bones was studied, together with the depth of PA imaging and measurement in bones. Then, the possibility of PA imaging of bones by raster scanning of the focusing transducer was studied. The micro-CT images of the bovine ribs with and without ethylenediaminetetraacetic acid (EDTA) treatment indicated that the PA images could present the changes of bone microstructure result from the EDTA treatment. By using PA spectral analysis (PASA), the bone samples with and without the treatment of EDTA solution can be distinguished, and the microstructures can be characterized. This study was based on the bovine bone whose size comparable to human bones, suggesting that PA technology can be used as a novel bone diagnostic technique.

       PDF全文        Chinese Optics Letters ，2020年第18卷第12期 pp.12      

Zhong Xin   Wang Xinwei   Sun Liang   Zhou Yan  

      摘要 + 此论文可免费阅读 (可能需要登录)

An enhancement method of rapid lifetime determination is proposed for time-resolved fluorescence imaging to discriminate substances with approximate fluorescence lifetime in forensic examination. In the method, an image-Exclusive-OR treatment with filter threshold adaptively chosen is presented to extract region of interest from dual-gated fluorescence intensity images, and then the fluorescence lifetime image is reconstructed based on rapid lifetime determination algorithm. Furthermore, a max-min threshold filtering is developed to automatically realize visualization enhancement of the lifetime image. In proof experiments, compared with traditional fluorescence intensity imaging and rapid lifetime determination method, the proposed method automatically distinguishes altered and obliterated document written by two brands of highlighters with the same color and close fluorescence lifetime.

       PDF全文        Chinese Optics Letters ，2021年第19卷第4期 pp.04      

Chen Li   Kumar Singh Rakesh   Dogariu Aristide   Chen Ziyang   Pu Jixiong  

      摘要 + 此论文可免费阅读 (可能需要登录)

Encoding information using the topological charge of vortex beams has been proposed for optical communications. The conservation of the topological charge on propagation and the detection of the topological charge by a receiver are significant in these applications and have been well established in free-space. However, when vortex beams enter a diffuser, the wavefront is distorted, leading to a challenge in the conservation and detection of the topological charge. Here, we present a technique to measure the topological charge of a vortex beam obscured in the randomly scattered light. The results of the numerical simulations and experiments are presented and are in good agreement. In particular, only a single-shot measurement is required to detect the topological charge of vortex beams, indicating that the method is applicable to a dynamic diffuser.

       PDF全文        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Wang Pengwei   Wang Chenglong   yu cuiping   yue shuai   Gong Wenlin   Han Shensheng  

      摘要 + 此论文可免费阅读 (可能需要登录)

We propose a color ghost imaging approach where the object is illuminated by three-color non-orthogonal random patterns and the object's reflection/transmission information is received by only one single-pixel detector, and both the sparsity constraint and non-local self-similarity of the object are utilized in the image reconstruction process. Numerical simulated results demonstrate that the imaging quality can be obviously enhanced by ghost imaging via sparsity constraint and non-local self-similarity (GISCNL), compared with the reconstruction methods where only the object’s sparsity is used. Factors affecting the quality of GISCNL, such as the measurement number and the detection SNR, are also studied.

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

Pang Chi   Li Rang   Li Ziqi   Dong Ningning   Wang Jun   Ren Feng   Chen Feng  

      摘要 + 此论文可免费阅读 (可能需要登录)

Copper nanoparticles (Cu NPs) are synthesized under the near-surface region of the Nd:YAG crystal by direct Cu+ ions implantation. Subsequently, monolithic ridge waveguide with embedded Cu NPs is fabricated by C4+ ions implantation and diamond saw dicing. Nonlinear optical response of the sample is investigated by Z-scan technique and pronounced saturable absorption is observed at 1030 nm femtosecond laser. Based on the obvious saturable absorption of Cu NPs embedded Nd:YAG crystal, 1 μm monolithic mode-locked pulsed waveguide laser is implemented by evanescent field interaction between NPs and waveguide modes, reaching the pulse duration of 24.8 ps and repetition rate of 7.8 GHz. The work combines waveguides with NPs, achieving pulsed laser devices based on monolithic waveguide chip.

       PDF全文        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Zhukova Lia   Salimgareev Dmitrii   Lvov Alexandr   Lashova Anastasiya   Korsakov Alexandr   Belousov Dmitrii  

      摘要 + 此论文可免费阅读 (可能需要登录)

The article is devoted to the technology for obtaining optical ceramics of AgBr – TlI and AgBr-TlBr0.46I0.54 systems and manufacture samples with different compositions. The new heterophase crystal ceramics is transparent without absorption windows in the spectral range from 1.0 to 60.0 microns. In the ceramics' transparency spectra based on the AgBr – TlI and AgBr – TlBr0.46I0.54 systems fusibility diagrams, with an increase in the thallium halides mass fraction, as well as the replacement of bromine ion with iodine, the maximum transparency shifts to a long infrared region.

       PDF全文        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Zhu Jing   Xu Shiqing   Lei Lei   Huang feifei   Xiao Zhen  

      摘要 + 此论文可免费阅读 (可能需要登录)

Up-converting(UC) perovskite Er3+-doped PbTiO3 (Er-PTO) nanoparticles with green and red emissions were synthesized via hydrothermal method. The UC properties were manipulated by adjusting the concentration of Er3+ ions dopant. The green emission intensity was decreased as the doping concentration increased from 1 mol% to 4 mol%, whereas the red emission intensity was increased. The influences of Er3+ ions on the temperature-sensing performance were further investigated. The results demonstrated that Er-PTO nanoparticles with doping 1 mol% concentration of Er3+ ions possessed a sensitivity of 3.1×10-3 K-1 at 475 K, presenting a high potential in optical heating devices.

       PDF全文        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Wang Guanxue   Miao Yu   Li Yang   Shan Xinzhi   Gao Xiumin  

      摘要 + 此论文可免费阅读 (可能需要登录)

The unevenly distributed Lorentz-Gaussian beams are difficult to reproduce in practice, (R2-Q1) because it requires modulation in both amplitude and phase terms. Here a new linearly polarized Lorentz-Gauss beam modulated by a helical axicon (LGB-HA) is calculated and the two various experimental generation methods of this beam, (R2-2-Q1) Fourier Transform Method (FTM) and Complex-Amplitude Modulation (CAM) method are depicted. Compared with Fourier Transform Method, Complex-Amplitude Modulation method can modulate the phase and amplitude simultaneously by only one reflection-type phase-only liquid crystal spatial light modulator. Both the two methods are coincident with the numerical results. (R1-Q6) (R2-Q2) Yet the Complex-Amplitude Modulation is more simple, efficient and has a higher degree of conformance through data comparison. (R1-Q6) (R2-Q2) In addition, considering some barriers existed in shaping and reappearing the complicated Lorentz-Gauss beam with heterogeneous distribution, the evolution regularities of the beams with different parameters (B, n, m) were also implemented.

       PDF全文        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Pang Xiaoyan   Feng Chen   Zhao Xinying  

      摘要 + 此论文可免费阅读 (可能需要登录)

The evolution of the spin density vectors (SDVs) is studied in a strongly focused composite field. It is found that the SDVs can be spiral along the propagation axis and they are perpendicular to ys direction on the ys axis. This behavior is governed by the Gouy phase difference between the field polarization components. The 60° rotation of the spatial distribution of the transverse SDVs is also generated, which is found to be controlled by the Gouy phase difference between the field orbital angular momentum modes. Additionally, the spin density singularities are observed in the evolution of the SDVs.

       PDF全文        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Fang Wei   Yang Kui   Li Haiyuan  

      摘要 + 此论文可免费阅读 (可能需要登录)

To balance the accuracy and efficiency in multiple-view triangulation with sequential images, a high-efficiency propagation-based incremental triangulation (INT) method, carving 3D scene point by updating the incoming feature track one-by-one without iterations is proposed. Based on the INT method, a more accurate iteration-limited incremental triangulation (ININT) method is also established with few iterations to bound the propagated errors, ensuring the accuracy of subsequent 3D reconstruction. Finally, experimental results demonstrate that the proposed methods can balance the efficiency and accuracy in different multiple-view incremental triangulation situations.

       PDF全文        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Deng Ming   Ren Tangxuan   Wang Jian   Chen Lin  

      摘要 + 此论文可免费阅读 (可能需要登录)

Retroreflector that reflects light along its incident direction has found numerous applications in photonics, but the available metasurface schemes suffer from the issue of narrow bandwidth and/or a single angle of incidence. Here a retroreflector using double layers of achromatic gradient metasurfaces is reported, which can realize retroreflection over a continuous range of incidence angles within a wide spectral band. The first metasurface serves as a transmissive achromatic lens that performs a broadband spatial Fourier transform and its inverse, while the second metasurface works as a reflective achromatic lens that undergoes a wavelength- and position-dependent phase dispersions. Using this design strategy, a near-infrared retroreflector comprised of silicon nanopillars with the cross-sections of square pillars and square holes is numerically demonstrated, providing a high-performance retroreflection for polarization-independent incident light waves over a continuous range of incidence angles from 0 to 16° within an extremely broad wavelength range between 1.35 and 1.95 μm. The scheme herein can offer a design strategy of broadband retroreflectors, and impact numerous photonics applications.

       PDF全文        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Zhang ZeXin   Tian Jinrong   Xu Changxing   Xu Runqin   Cui Youshuo   Zhuang Bihui   Song Yanrong  

      摘要 + 此论文可免费阅读 (可能需要登录)

Noise like pulses having pedestal of 690 fs and spike of 59.6 fs were generated in a nonlinear Yb-doped fiber amplification system. The seed source is a mode-locked Yb-doped fiber laser by nonlinear polarization rotation, and dissipative soliton pulses were obtained in it. Then the dissipative soliton pulses passed through a 7.6-m dispersive fiber to enhance the dispersion and nonlinearity. On further the dissipative soliton pulses were launched into an Yb-doped fiber nonlinear amplifier, and stable noise like pulses with a pedestal of 6.26 ps and spike of 227 fs were achieved. Finally, by a grating pair, the pedestal and spike of the noise like pulses were effectively compressed to 690 fs and 59.6 fs, respectively. To the best of our knowledge, this is the shortest pedestal demonstrated in noise like pulses operating at 1 µm.

       PDF全文        Chinese Optics Letters ，2020年第18卷第12期 pp.12      

VIJAYAKUMAR   A.   Katkus Tomas   Ng Soon Hock   Juodkazis Saulius  

      摘要 + 此论文可免费阅读 (可能需要登录)

Fresnel incoherent correlation holography (FINCH) is a well-established incoherent imaging technique. In FINCH, three self-interference holograms are recorded with calculated phase differences between the two interfering, differently modulated object waves and projected into a complex hologram. The object is reconstructed without the twin image and bias terms by a numerical Fresnel back propagation of the complex hologram. A modified approach to implement FINCH by a single camera shot by pre-calibrating the system involving recording of the point spread function library and reconstruction by a non-linear cross-correlation has been introduced recently. The expression of the imaging characteristics from the modulation functions in original FINCH and the modified approach by pre-calibration in spatial and polarization multiplexing schemes are reviewed. The study reveals that a reconstructing function completely independent of the function of the phase mask is required for the faithful expression of the characteristics of the modulating function in the image reconstruction. In polarization multiplexing method by cross-correlation, a partial expression was observed, while in spatial multiplexing method by cross-correlation, the imaging characteristics converged towards a uniform behavior.

       PDF全文        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Liu Xu   TAN CHAOYONG   Cheng Yong   Wei Jingsong   Mengzhen Zhu   CHEN XIA   MI CHAOWEI  

      摘要 + 此论文可免费阅读 (可能需要登录)

To obtain short pulse width and high peak power laser, 7 kHz sub-nanosecond microchip laser amplified by a grazing incidence double pass slab amplifier is experimentally demonstrated in this letter. We use a compact side-pumped Nd:YVO4 bounce amplifier with grazing incidence beam for achieving high gains and power extraction. Laser output power of 7.37 W at 7 kHz, 1.2 MW pulse peak power with 877 ps duration and 1.05 mJ energy, 25 pm spectral width, and near diffraction limited mode beam quality are achieved, the optical-to-optical efficiency is 18%. The laser is packaged in a volume of 356×226×84 mm3, may be used for applications such as laser altimeters and ladar systems.

       PDF全文        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Kong Hui   Bian Tian   Yao Jiyong   Ye Qing   Sun Xiaoquan  

      摘要 + 此论文可免费阅读 (可能需要登录)

The temperature tuning of BGSe was demonstrated for the first time. When the temperature of BGSe (56.3°，0°) rised from 30℃ to 140℃, the idle light under type I raised from 3637 nm to 3989 nm, the tunable range reached 352 nm, and the ∆λ_2/ΔT reached 3.20 nm/℃. We calculated the phase matching curve of BGSe when ∅ and T take different values. The relationship between θ and ∆λ_2/ΔT was obtained by fixing ∅ at 0°. The maximum ∆λ_2/ΔT and its corresponding (θ, ∅), phase matching type were reported under different fixed λ_2 (3μm,3.2μm,…5μm).

       PDF全文        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Li Shangyuan   Cao Haidong   Xiaoping Zheng  

      摘要 + 此论文可免费阅读 (可能需要登录)

A photonic approach to concurrently measure the angle-of-arrival (AOA) and the chirp rate of a linear frequency modulated (LFM) signal is proposed and experimentally demonstrated. The measurement is achieved by estimating the differential frequency of a two-tone signal output by a dual-parallel Mach-Zehnder modulator and an additional asymmetry Mach-Zehnder interferometer. Experiments show that the AOA and the chirp rate are measured simultaneously, with an AOA measurement error of $\pm 0.1^\circ$ at an SNR of 9.6 dB. When SNR = -10.4 dB, the AOA error is $\pm 1.3^\circ$ and the chirp rate, measured as $210.2\pm1.5\ \rm{Hz/ps}$ has a standard deviation of $0.7\%$. The measured chirp rate agrees well with the real LFM signal.

       PDF全文        Chinese Optics Letters ，2020年第18卷第12期 pp.12      

Wu Han   Han Bing   wang zinan   Liang Houkun  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this letter, we experimentally investigate fast temporal intensity dynamics and statistical properties of the cladding-pumped Er/Yb co-doped random Rayleigh feedback fiber laser (EYRFL) for the first time, to the best of our knowledge. By using the optical spectral filtering method, strong and fast intensity fluctuations with the generation of extreme events are revealed at the output of EYRFL. The statistics of the intensity fluctuations strongly depends on the wavelength of the filtered radiation, and the intensity probability density function (PDF) with heavy tail is observed in the far wings of the spectrum. We also find the PDF of the intensity in the central part of the spectrum deviates from the exponential distribution, and has the dependence on the laser operating regimes, which indicates some correlations among different frequency components exist in the EYRFL radiation and may play an important role in the random lasing spectrum stabilization process.

       PDF全文        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Tang Kaifei   Liao Wenbin   Lin Da   Li Bingxuan   chen weidong   Zhang Ge  

      摘要 + 此论文可免费阅读 (可能需要登录)

The behavior of self-polarization emission in Nd:YAG/Cr4+:YAG lasers has been proved in some cases, however, the degree and direction of polarization were often sensitive and unstable. We experimentally observed different beam profiles versus the angle of polarizer relative to the polarization direction of laser. In order to explore the polarization mechanism, the dynamics of intracavity polarized eigenmodes were analyzed theoretically. Simulative results were well consistent with our experimental observations. It indicated that the linearly self-polarization emission was a composite state rather than intrinsic state. This study contributed to the improvement of the polarization stability in Nd:YAG/Cr4+:YAG passively Q-switched lasers.

       PDF全文        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Gao Chao   Lei Bing  

      摘要 + 此论文可免费阅读 (可能需要登录)

We report a spatially modulated polarimetry scheme by using a zero-order vortex half-wave retarder (ZVHR) and spatial Fourier analysis method. A ZVHR is employed to analyze the input polarized light and convert it into a vectorial optical field, and an analyzer is set after the ZVHR to form an hourglass intensity pattern due to the spatial polarization modulation, and then the input light’s Stokes parameters can be calculated by spatial Fourier analysis of the hourglass pattern with a single shot. The working principle of the polarimeter has been analyzed by the Stokes-Mueller formalism, and some quantitative measuring experiments of different polarization states have been demonstrated, and the experimental results indicate that the proposed polarimeter is accurate, robust and simple to use.

       PDF全文        Chinese Optics Letters ，2021年第19卷第2期 pp.02      

Chen Shuaidong   Liu Bo   Mao Yaya   Ren Jianxin   Song Xiumin   Ullah Rahat   Zhao Delin   Jiang Lei   Han Shun   Zhao Jianye   Shen Jiajia   Liu Xueyang  

      摘要 + 此论文可免费阅读 (可能需要登录)

A novel physical layer data encryption using two-level constellation masking in three-dimension carrier-less amplitude and phase modulation passive optical network (3D-CAP-PON) is proposed in this letter. The chaotic sequence generated by the Chua's circuit model realizes two-level encryption of displacement masking and constellation rotation for 3D constellation. We successfully conduct an experiment demonstrating 8.7 Gb/s 3D-CAP-8 data transmission over 25 km standard single-mode fiber (SSMF). With two-level constellation masking, a key space size of 2.1×10⁸⁵is achieved to bring about high security and good encryption performance, suggesting broad application prospects in future short-range secure communications.

       PDF全文        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Dai Haitao   Mohamed Zolkefl A.Y.   Xiao Aixiang   Xue Yongxiang   Guo Ziyang   Zhang Yu   Zhang Xiaodong   Liu Changlong  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this letter, we report on an Airy-like beam of magnetostatic surface spin wave (AiBMSSW) supported on the ferromagnetic film, which is transferred from optical field. The propagation properties of AiBMSSW were verified with micromagnetic simulation. From simulation results, the typical parabolic trajectory of Airy-type beam was observed by encoding 3/2 phase pattern into excitation sources. The simulation results are coincident well with design parameters. Furthermore, simulated results showed that the trajectories of AiBMSSW beam could be tuned readily with varied external magnetic field. This work can extend the application scenario of SWs.

       PDF全文        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Zhang Wending   Zhang Lu   Meng Chao   Gao Feng  

      摘要 + 此论文可免费阅读 (可能需要登录)

We present the generation of the nanosecond cylindrical vector beams (CVBs) in two-mode fiber (TMF) and its applications of stimulated Raman scattering. The nanosecond (1064 nm, 10 ns, 10 Hz) CVBs has been directly produced with mode conversion efficiency of ~18 dB (98.4%) via an acoustically-induced fiber grating (AIFG), and then the stimulated Raman scattering signal is generated based on the transmission of the nanosecond CVBs in a 100-meters length TMF. The transverse mode intensity and polarization distributions of the 1st-order Stokes shift component (1116.8 nm) is consistent with the nanosecond CVBs pump pulse.

       PDF全文        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Pan Yue   Gao Xu-Zhen   Ma Rende   Tu Chenghou   Li Yongnan   Wang Huitian  

      摘要 + 此论文可免费阅读 (可能需要登录)

Orbital angular momentum (OAM), as a fundamental parameter of photon, has attracted great attention in recent years. Although various properties and applications have been developed by modulating the OAM of photons, there is rare research about the non-uniform OAM. We propose and generate a new kind of continuously tunable azimuthally non-uniform OAM for the first time, which is carried by hybridly polarized vector optical field with cylindrically symmetric intensity profile and a complex polarization singularity. We also present the perfect vector optical field carrying non-uniform OAM with fixed radius independent of topological charges, which can propagate steadily without radial separation, solving the problem of the unsteady propagation due to the broaden OAM spectrum of the non-uniform OAM. This new kind of tunable non-uniform OAM with cylindrical symmetric intensity profile, complex polarization singularity and propagation stability enriches the family of OAM, and can be widely used in many regions such as optical manipulation, quantum optics, optical communications and so on.

       PDF全文        Chinese Optics Letters ，2020年第18卷第12期 pp.12      

Wang Ju   JIA Ting   Wang Shuaishuai   Li Tianyu   Ma Chuang   Xie Tianyuan   Yu Yang   Yu Jinlong  

      摘要 + 此论文可免费阅读 (可能需要登录)

We propose a concept of wavelength synchronization to ensure the stability of ultra-dense channels in ultra dense wavelength division multiplexing passive optical network (UDWDM-PON) transmitter. A mode-locked laser (MLL) is used to provide wavelength references for users. By injection locking semiconductor laser, the separation of wavelength reference is realized in optical line terminal (OLT). The downlink and uplink wavelength references are interlaced distributed to facilitate the synchronization of uplink carriers. In optical network unit (ONU), the uplink optical carriers are filtered by injection locking semiconductor lasers, which achieve wavelength synchronization for the uplink users. In this paper, an adaptive wavelength synchronization transmitter for UDWDM-PON is realized with a channel spacing of 5 GHz.

       PDF全文        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Zhang Jian   Tu Rui   Huang Chao   Yao Xiaoli   Hu Xin   Ge Haixiong   Zhang Xuefeng  

      摘要 + 此论文可免费阅读 (可能需要登录)

Nanogap plasmonic structures with strong coupling between separated components have different responses to orthogonal polarized light, giving rise to giant optical chirality. Here, we proposed a 3D nanostructure consists of two vertically and twistedly aligned nanogaps, showing the hybridized charge distribution within 3D structures. It is discovered that the structure twisted with 60^o performs plasmonic coupling behaviour with/without gap mode for different circular-polarized plane waves, showing giant chiral response (ΔT) of 60% at the wavelength of 1550 nm. By controlling the disk radius and the insulator layer, the CD signal can be further tuned between 1538~1626 nm.

       PDF全文        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Wang Yanyi   WANG KAIHUI   Zhou Wen   Yu Jianjun  

      摘要 + 此论文可免费阅读 (可能需要登录)

A novel and simple scheme of photonic aided vector millimeter-wave (mm-wave) signal generation without a digital to analog converter (DAC) is proposed. Based on our scheme, 20Gb/s 4-ary quadrature amplitude modulation (4-QAM) mm-wave signal is generated without using a DAC. The experiment results demonstrate that the bit error rate (BER) of 20Gb/s 4-QAM mm-wave signal can reach below hard-decision forward-error-correction (HD-FEC) threshold of 3.8x10-3 after a delivery over 1-m wireless distance. Because the DAC is not required, it can reduce the system cost. Besides, by using photonic technology, the system is easily integrated to create large-scale production and application in high- speed optical communication

       PDF全文        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Zhou Yuewen   Zhang Fangzheng   Pan Shilong  

      摘要 + 此论文可免费阅读 (可能需要登录)

We propose a photonics-assisted equivalent frequency sampling (EFS) method to analyze the instantaneous frequency of broadband linearly frequency modulated (LFM) microwave signals. The proposed EFS method is implemented by a photonic scanning receiver which is operated with a frequency scanning rate slightly different from the repetition rate of the LFM signals. Compared with the broadband LFM signal analysis based on temporal sampling, the proposed method avoids the use of high-speed analog to digital converters and the instantaneous frequency acquisition realized by frequency-to-time mapping is also simplified since real-time Fourier transformation is not required. Feasibility of the proposed method is verified through an experiment, in which frequency analysis of Ka-band LFM signals with a bandwidth up to 3 GHz is demonstrated with a moderate sampling rate of 100 MSa/s. The proposed method is highly demanded for analyzing the instantaneous frequency of broadband LFM signals used in radar and electronic warfare systems.

       PDF全文        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Sun Hao   Yang Jie   Liu Hengzhu   Zheng Xin   Wu Dan  

      摘要 + 此论文可免费阅读 (可能需要登录)

Recently reported plasmon-induced transparency (PIT) in metamaterials endows the optical structures in classical system with quantum optical effects. In particular, nonreconfigurable nature in metamaterials makes multifunctional applications of PIT effect in terahertz communications and optical networks remain a great challenge. Here we present an ultrafast process-selectable modulation of PIT effect. By incorporating silicon islands into diatomic metamaterials, the PIT effect is modulated reversely, depending on the vertical and horizontal configurations, with giant modulation depth as high as 129% and 109%. Accompanied by the enormous switching of transparent window, remarkable slow light effect occurs.

       PDF全文        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Yuan Qizhang   Feng Xunli  

      摘要 + 此论文可免费阅读 (可能需要登录)

Recently the nested Mach-Zehnder interferometer [Phys. Rev. Lett.111, 240402 (2013)] was modified by adding Dove prisms in a paper [Quantum Stud.: Math. Found. 2, 255 (2015)], and an interesting result is that, after the Dove prisms being inserted, a signal at the first mirror of the nested interferometer was obtained. But according to the former original paper, the photons have never been present near that mirror. In this work we interpret this result naturally by resorting to the three path interference method. Moreover, we find that even the photons have been somewhere, they can hide the trace of being there.

       PDF全文        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Li Wentao   Zhou Jian  

      摘要 + 此论文可免费阅读 (可能需要登录)

In order to solve the shortcomings of the traditional contact and non-contact rotational speed measurement methods, and further improve the accuracy and universality of the rotational speed measurement, an instantaneous rotational speed measurement method based on laser Doppler technology is proposed. The principle of laser Doppler velocimeter is expounded, and the composition and working principle of the new system are discussed in detail. Theoretical and experimental results show that: the new rotational speed measurement system belongs to the non-contact measurement method, which greatly improves the applicability and accuracy. Compared to the commonly used speed measurement method, the measurement accuracy of the new speed measurement system will not be affected by the system’s installation angle deviation, and it does not need to measure the radius of the rotating body, so the influence of the radius fluctuation of the rotating body on the measurement accuracy can be avoided while outputting the rotational speed in real time. The relative error of the rotational speed measurement is less than 0.06% (1σ).

       PDF全文        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Shen Danyang   Qian Jing   Wang Chengwei   Wang Guande   Wang Xuehui   Zhao Quanzhong  

      摘要 + 此论文可免费阅读 (可能需要登录)

One-step precipitation of Ag nanoparticles in Ag+-doped silicate glasses was achieved through a focused picosecond laser with a high-repetition rate. Absorption spectra and transmission electron microscopy (TEM) confirmed that metallic Ag nanoparticles were precipitated within glass samples in the laser-written domain. The surface plasmon absorbance fits well with the experimental absorption spectrum. The nonlinear absorption coefficient β is determined to be 2.47 × 10−14 m/W by fitting the open aperture Z-scan curve, which originating from the intraband transition in the s-p Ag band. The formation mechanism of Ag-glass nanocomposites is discussed as well.

       PDF全文        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Lu Cuicui   Ma Lifeng   Li Jing   Liu Zhouhui   Zhang Yuxuan   Zhang Nianen   Zheng Shuqiao  

      摘要 + 此论文可免费阅读 (可能需要登录)

The research on nanophotonic devices has made great progress during the past decades. It is the unremitting pursuit of researchers that realize various device functions to meet practical applications. However, most of the traditional methods rely on human experience and physical inspiration for structural design and parameter optimization, which usually require a lot of resources, and the performance of the designed device is limited. Intelligent algorithms, which are composed of rich optimized algorithms, show a vigorous development trend in the field of nanophotonic devices in recent years. The design of nanophotonic devices by intelligent algorithms can break the restrictions of traditional methods and predict novel configurations, which is universal and efficient for different materials, different structures, different modes and different wavelengths, etc. In this review, intelligent algorithms for designing nanophotonic devices are introduced from their concepts to their applications, including deep learning methods, the gradient-based inverse design method, swarm intelligence algorithms, individual inspired algorithms and some other algorithms. The design principle based on intelligent algorithms and the design of typical new nanophotonic devices are reviewed. Intelligent algorithms can play an important role in designing complex functions and improving the performances of nanophotonic devices, which provide new avenues for the realization of photonic chip.

       PDF全文        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Shan Tao   Ma Jianshe   Wu Tianfeng   Shen Zanqiu   Su Ping  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this letter, a single scattering turbulence model in a narrow beam case for ultraviolet (UV) communication is proposed based on the division of the effective scattering volume. This model takes the variation of atmospheric scattering, absorption, and turbulence in different paths into account. Meanwhile, the applicable transceiver configurations of this model are provided by analyzing path loss error caused by the single scattering assumption in the UV channel. Furthermore, we investigate the effect of turbulence on the probability density function of the arriving power in both coplanar and non-coplanar scenarios. The averaging effect of multipath propagation on the arriving power’s fluctuations is presented. Then the bit-error-rate performance is also studied. This work provides an efficient way for the UV turbulence channel estimation.

       PDF全文        Chinese Optics Letters ，2020年第18卷第12期 pp.12      

Liu Yaoxiang   Wang Tie-Jun   Chen Na   Guo Hao   sun haiyi   Zhang Lu   Qi Zheng   Leng Yuxin   Li Ruxin   Wang Zhanshan  

      摘要 + 此论文可免费阅读 (可能需要登录)

We report on a simultaneous generation of double white light lasers through filamentation by focusing a femtosecond laser pulse. The appearance of the two white light lasers can be controlled by tilting the focusing lens and spectral bandwidth, pulse energy of the double white light lasers were controlled by tuning laser filamenting pulse energy and polarization. Two white light lasers with pulse energies of 1.54 mJ and 1.84 mJ, respectively, were generated with the pump laser energy of 7.43 mJ. Besides being beneficial in understanding the multiple white light lasers generation process through multiple filamentation and its control, the results are also valuable for white light laser-based applications.

       PDF全文        Chinese Optics Letters ，2020年第18卷第12期 pp.12      

leng yuxin   liu keyang   liu yanqi   tang yunhai   chen junchi   wang cheng   Liu Xingyan   wang xiaobin   long yingbin   xu yi   Peng Yujie   lu xiaoming   Liu Zhengzheng  

      摘要 + 此论文可免费阅读 (可能需要登录)

A novel tiled Ti: sapphire (Ti:S) amplifier was experimentally demonstrated with >1 J amplified chirped pulse output. Two Ti:S crystals having a dimension of 14 × 14 × 25 mm were tiled as the gain medium in a four-pass amplifier. A maximum output energy of 1.18 J was obtained with 2.75 J pump energy. The energy conversion efficiency of the tiled Ti:S amplifier was comparable with a single Ti:S amplifier. The laser pulse having the maximum peak power of 28 TW was obtained after the compressor. Moreover, the influence of the beam gap on the far field was discussed. This novel tiled Ti:S amplifier technique can provide a potential way for 100 PW or EW lasers in the future.

       PDF全文        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Arslan Halil   Pehlivanoz Bahar  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this study the effects of purification, dehydration and coagulation processes on the absorption and reduced scattering coefficients of chicken liver tissues have been investigated by using single integrating sphere system. The purification process performed on the tissue samples to remove blood residues has been found to cause a slight change in the optical parameters. Although the dehydration process brings about an increase in the absorption coefficient due to the water loss, no direct relationship has been observed between the reduced scattering coefficient and the dehydration level of the tissue. In addition, it has been observed that there was a relatively small increase in absorption coefficient and a significant increase in reduced scattering coefficient after the coagulation process. Therefore, it can be said that the optical penetration depth decreased significantly after dehydration and coagulation processes unlike blood purification. Moreover, fluence rate distributions inside the fresh, blood purified, dehydrated and coagulated tissue models have been investigated by using MCML simulation code.

       PDF全文        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Guo Junda   Diao Zhihui   Yan Shufeng   Zhang Enqi   Kong Lingsheng  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this Letter, we present a display system based on curved screen and parallax barrier, which provides stereo images with a horizontal field of view of 360° without wearing any eyewear, to achieve an immersive autostereoscopic effect. The display principle and characteristics of this display system are studied theoretically in detail. Three consecutive pixels on curved screen and parallax barrier form a display unit, which can generate separate viewing zones for the left and right eyes, respectively. Simulation and experimental results show that non-crosstalk effect can be obtained in the viewing zones, which proves the effectiveness of this display system. This study provides some new ideas for the improvement of the autostereoscopic display and to enable envisioned applications in virtual reality technology.

       PDF全文        Chinese Optics Letters ，2021年第19卷第1期 pp.01      

Chen Sanbin   Li Jianlang   Ueda Ken-ichi  

      摘要 + 此论文可免费阅读 (可能需要登录)

A rotating Nd:YAG disk laser resonator for efficiently generating vector beam with azimuthal and radial polarization is demonstrated. In the study, the laser crystal is rotary for the thermal alleviation and the polarization discrimination uses a c-cut ytterbium vanadate (YVO4). The laser output could be switched between azimuthal and radial polarizations by simply adjusting the cavity length. The laser power reached 4.38 W azimuthally and 4.64 W radially polarized beams at the slope efficiencies of 45.3% and 48.5%, respectively. Our study proved that an efficient, high-power vector rotary disk lase would be realistic.

       PDF全文        Chinese Optics Letters ，2020年第18卷第12期 pp.12      

Li Jiaming   Li Chuangkai   Chen Yun   Zhao Nan   hou zhiyun   Zhang Qingmao   Zhou Guiyao  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this work, we demonstrated the Bi/Al-codoped silica glass prepared by the laser additive manufacturing technology for the first time. The bismuth was uniformly doped into the silica matrix. The hydroxyl content of the glass sample was measured to be 29.36 ppm. Using 808 nm LD as the excitation source, a broadband NIR emission from 1000 to 1600 nm was obtained. The emission peak was centered at 1249 nm and the corresponding FWHM was more than 400 nm. The results show that the laser additive manufacturing technology is promising to fabricate Bi-doped core materials with high homogeneity and broader emission band, which is beneficial to solve the communication capacity crunch and promotes the development of fiber communication in the upcoming 5th and 6th generation systems.

       PDF全文        Chinese Optics Letters ，2020年第18卷第12期 pp.12      

Chen Junbao   Wang Ming   Xia Wei  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this work, a neural network (NN) method is developed for the pulse duration inferring for an erbium-doped fiber laser at 1550 nm. Experimentally, the interferometric autocorrelation trace is observed clearly with the use of the TPA effect in a GaAs photodiode. The intensity autocorrelation function is curve-fitted by the NN with an appropriate performance, and the measuring accuracy is consistent with a commercial autocorrelator. Compared with the Levenberg–Marquardt curve-fitting method, the NN can retrieve the intensity autocorrelation function more stably and has a certain noise reduction ability, simplifying the signal processing for a TPA photodiode-based autocorrelator.

       PDF全文        Chinese Optics Letters ，2020年第18卷第12期 pp.12      

Wang Liangwei   Shi jing  

      摘要 + 此论文可免费阅读 (可能需要登录)

Squeezed vacuum, as a nonclassical field, has many interesting properties and results in many potential applications for quantum measurement and information processing. Here, we investigate a single atom cavity QED system driven by a broadband squeezed vacuum. In the presence of the atom, we show that both the mean photon number and the quantum fluctuations of photons in the cavity undergo a significant depletion due to the additional transition pathways generated by the atom-cavity interaction. We also show that two-photon excitation can be significantly suppressed by the quantum destructive interference when the squeezing strength is very weak. Theses results presented here is helpful to understand the quantum nature of the broadband squeezed vacuum.

       PDF全文        Chinese Optics Letters ，2020年第18卷第12期 pp.12      

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      

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      

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      

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      

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      

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      

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      

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      

Tang Jiao   Xu Jiao   Zheng Zhiwei   Dong Jun   Dong Hu   Qian Shenyou   Guo Jun   Jiang Leyong   Xiang Yuanjiang  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this paper, we have shown that giant Goos-Hänchen shift of light beam reflected at terahertz frequencies can be achieved by using a composite structure where monolayer graphene is coated on one-dimensional photonic crystal separated by a dielectric slab. This giant Goos-Hänchen shift originates from the enhancement of the electrical field owing to the excitation of optical Tamm states at the interface between the graphene and one-dimensional photonic crystal. It is shown that the Goos-Hänchen shift in this structure can be significantly enlarged negatively and can be switched from negative to positive due to the tunability of graphene’s conductivity. Moreover, the Goos-Hänchen shift of the proposed structure is sensitive to the relaxation time of graphene and the thickness of the top layer, making this structure a good candidate for dynamic tunable optical shift device in terahertz regime.

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

Zhang Yixuan   Gao Chunqing   Wang Qing   Na Quanxin   Zhang Meng   gao mingwei   Huang Shuai  

      摘要 + 此论文可免费阅读 (可能需要登录)

A novel 1 kHz single-frequency Q-switched Er:YAG laser pumped by a 1470 nm laser diode (LD) is demonstrated. The 500 ns, 5.52 mJ single-frequency diffraction-limited pulses are obtained by using a ‘Ramp-fire’ injection-seeding technique and an optical feedback architecture. The half-width of the pulse spectrum is measured to be 1.47 MHz by using the heterodyne technique. The beam quality M2 factors are measured to be 1.18 and 1.24 in x and y directions, respectively.

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

ZOU Xihua   Li Peixuan   Pan Wei   Yan Lianshan  

      摘要 + 此论文可免费阅读 (可能需要登录)

As a key figure-of-merit for high-performance microwave filters, the out-of-band noises rejection is of critical importance in a wide range of applications. This paper overviews the significant advances in the photonic microwave filters (PMFs) having ultra-high rejection ratio for out-of-band noise suppression over the last ten years. Typically, two types of PMFs, the bandpass and bandstop ones, are introduced with fundamental principles, detailed approaches, and then the cutting-edge results for noises rejection. Ultra-high noise rejection ratios of ~80 dB and >60 dB have been demonstrated for single-passband and single-stopband PMFs respectively, which are comparable with the state-of-art electronic filters operating in stringent conditions. These PMSs are also characterized by wide frequency coverage, low frequency-dependent loss, and strong immunity to electromagnetic interference, due to the intrinsic features from advanced photonics technology.

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

Li Ziqi   Li Rang   Pang Chi   Zhang Yuxia   Yu Haohai   Chen Feng  

      摘要 + 此论文可免费阅读 (可能需要登录)

Graphene and other extraordinary two-dimensional materials together with recent advances in optical modulators have set the foundations for the widespread applications of next-generation optoelectronic devices. In this paper, we report on the high-performance fundamentally mode-locked waveguide laser modulated by CVD-grown WSe2 as a saturable absorber. By incorporating WSe2 sample into a monolithic Nd:YVO4 waveguide platform, 6.526 GHz picosecond pulsed laser generation have been achieved at the wavelength of 1 μm with pulse duration as short as 47 ps. This work indicates promising applications of WSe2 for the development of on-chip ultrafast photonics devices.

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

Li Miao   Chen Gui   Leng Jinyong   Chen Jinbao   Li Jinyan  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this work, non-isothermal bleaching of Yb-Li co-doped fiber was investigated. The Yb-Li co-doped fiber was beneficial to reduce the photodarkening (PD)-induced excess loss, and had no bad effect on the temperature of thermal bleaching (TB). Photodarkened fibers were bleached with different temperature ramp rates. The higher the ramp rate, the higher the complete bleaching temperature. The activation energy of the bleaching of Yb/Al/Li fiber was calculated by fitting, which was similar to that of Yb-doped fiber. It indicated that the mechanism of mitigating PD by Li co-doping was different from that of TB, and was not subject to temperature.

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

Li Guangji   Zhang Hongchao   Wang Chengmin   Pan Yunxiang   Lu Jian   Zhou Dayong  

      摘要 + 此论文可免费阅读 (可能需要登录)

The photoelectric properties of In_0.3Ga_0.7As solar cell applied in laser wireless power transmission(LWPT) was studied when irradiated by 1070nm continuous(CW) laser of various intensities. The influences of laser intensity on solar cell parameters extracted by pollination algorithm were analyzed quantitatively. Results show that conversion efficiency of the cell rose to the maximum and then decreased rapidly in the laser intensity range of 50-900mW/cm². With higher energy laser irradiation, the rise of ideality factor and reverse saturation current would lead to the degradation of voltage at maximum power point, which was the main reason for the decrease of conversion efficiency. The results provide basis for choosing the appropriate input energy in the case of different transmission systems.

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

Zhang Qi   Ren Juanjuan   Duan Xueke   Hao He   Gong Qihuang   Gu Ying  

      摘要 + 此论文可免费阅读 (可能需要登录)

Enhancing light-matter interaction in cavity quantum electrodynamics has aroused widespread interests in on-chip quantum information processing. Here we propose a hybrid nanotoroid-nanowire system to enhance photon-exciton interaction. A nanoscale gap is formed by placing a dielectric nanowire close to a dielectric nanotoroid, where the coupling coefficient between photon and emitter can achieve 5.55 times of that without nanogap. Meanwhile, the cavity loss and the spontaneous emission of the emitter will remain at small value to guarantee the realization of strong coupling. The method might hold promise for the research of nanophotonics, quantum optics and novel optical devices.

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

Khan Humayun   Haneef Muhammad   Bakhtawar Bakhtawar  

      摘要 + 此论文可免费阅读 (可能需要登录)

We report a theoretical demonstration for the creation of space time holes based on birefringence of reflection, transmission and the Goos H\"{a}chen shifts from a chiral medium. We observed space time holes in the reflection, transmission and their corresponding GH-shifted beams. Two space time holes are clearly detected in the regions of $0<t\leq5\tau_0$ and $-5w\leq y\leq 5w$ as well as in the regions of $-5\tau_0\leq t\leq0$ and $-5w\leq y\leq 5w$. These space time holes hide objects and information contents from observers and hackers. The objects and information contents are completely undetectable, thus events can be cloaked. The results of this paper have potential applications in invisibility of drone technology and secure communication of information in telecom industries.

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

Jiang Tian   Miao Runlin   Zhao Jie   Xu Zhongjie   Zhou Tong   Wei Ke   You Jie   Zheng Xin   Wang Zhenyu   Cheng Xiangai  

      摘要 + 此论文可免费阅读 (可能需要登录)

Broadband transient reflectivity traces were measured for Bi2Se3 thin films with various substrates via a 400 nm pump-white light probe setup. We have verified the existence of a second Dirac surface state in Bi2Se3 and qualitatively located it by properly analyzing the traces acquired at different probe wavelength. Referring to the band structure of Bi2Se3, the relaxation mechanisms for photo-excited electrons with different energies are also revealed and studied. Our results show a second rise of the transient reflection signal at the time scale of several picosecond. The types of substrate can also significantly affect the dynamics of the rising signal. This phenomenon is attributed to the effect of lattice heating and coherent phonon processes. The mechanism study in this work will benefit the fabrication of high-performance photonic devices based on topological insulators.

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

Jia Yuechen   Chen Feng  

      摘要 + 此论文可免费阅读 (可能需要登录)

Over the last years there has been tremendous progress with compact pulsed lasers based on various solid-state gain media such as crystals and glasses doped with laser-active ions. With the integration of increasingly colorful saturable-absorber materials, these small sources are capable of delivering stable pulses with duration as short as femtosecond and repetition rate exceeding ten gigahertz. These promising sources are known as solid-state waveguide lasers, which have become synonymous with miniaturization, integration, and functionality. This article overviews the progress in the development of passively Q-switched and mode-locked solid-state waveguide lasers employing diverse saturable absorbers. The most commonly used laser configurations, the state-of-the-art waveguide fabrication techniques and the experimental demonstrations of pulsed waveguide lasers are summarized and reviewed. Selected well-noted topics which may shape the future directions in this field are also presented.

       PDF全文        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

wang cong   Peng Qian   Xin Linlin   Liu Jie  

      摘要 + 此论文可免费阅读 (可能需要登录)

Two-dimensional (2D) materials have attracted intense attention in photonics and optoelectronics for their excellent nonlinear characteristics and is applied for the generation of laser pulse. Here, a active-passive Nd:GdVO4 1.3 μm laser is realized by using an acousto-optic modulator and gold nanobipyramids absorber. The pulse width of 150.5 ns is obtained in the doubly Q-switched laser. The compression ratio and enhancement time are 82.6 % and 16. The doubly Q-switched technology compresses the pulse width, improves the peak power and stabilizes the pulse, illustrating the doubly modulation technology opens the door of controllable ultrafast lasers based on 2D materials.

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

Liu Beiyun   You Congya   Zhao Chen   Shen Gaoliang   Liu Yawei   Li Yufo   Yan Hui   Zhang Yongzhe  

      摘要 + 此论文可免费阅读 (可能需要登录)

Graphene, as a novel 2D material, has attracted great of interest in optoelectronics owing to its high carrier mobility and broadband absorption. However, Graphene photodetector exhibits low photoresponsivity because of its low light absorption. In this work, we designed a graphene/MoSe₂ heterostructure photodetector, which exhibits photoresponse ranging from visible to near infrared and an ultrahigh photoresponsivity up to 1:3× 10⁴A/W at 550nm. The electron-hole pairs are excited in a few layered MoSe₂ and separaed by the built-in electric field. Large number of electrons shifted to graphene while holes remain in the MoSe₂, which creates a photogating effect. Moreover, the lifetime of electrons can be greatly extended because the trap of holes in MoSe₂ delays the recombination in the circuit. This photodetector represents powerful performance in the near-infrared wavelength regime and have the potential application in many area.

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

Li Chun   Leng Yuxin   Huo Jinjin  

      摘要 + 此论文可免费阅读 (可能需要登录)

This study investigates the applicability of a few-layer structure ReSe2 as a saturable absorber (SA) for demonstrating a passively Q-switched pulse laser. The ReSe2 SA had a modulation depth of 6.86%. The Q-switched experiment was successful in delivering a maximum average output power of 180 mW at the wavelength of 1906.5 nm. The optimal pulse train had a pulse width of 1.61 μs and a repetition rate of 28.78 kHz. The experiment results verify that the few-layer structure ReSe2 could behave as an excellent SA at all-solid-state lasers, increasing the selection of SA at near 2 μm laser.

       PDF全文        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Bai Zhengyang   Zhang Qi   Huang Guoxiang  

      摘要 + 此论文可免费阅读 (可能需要登录)

Electromagnetically induced transparency (EIT), a typical quantum interference effect, has been extensively investigated in coherent atomic gases. In recent years, it has been recognized that plasmonic analog of atomic EIT, called plasmon-induced transparency (PIT), is a fruitful platform for the study of EIT-like propagation and interaction of plasmonic polaritons. Many proposals have been presented for realizing PIT in various metamaterials, which possess many unique characters, including the suppression of absorption of electromagnetic radiation, the reduction of propagation velocity, etc. Especially, nonlinear PIT metamaterials, obtained usually by embedding nonlinear elements into meta-atoms, can be used to acquire enhanced Kerr effect resulted from the resonant coupling between radiation and the meta-atoms, and to actively manipulate structural and dynamical properties of plasmonic metamaterials. In this article, we review recent research progress on nonlinear PIT metamaterials, elucidate their interesting properties and promising applications. In particular, we give a detailed description on the propagation and interaction of nonlinear plasmonic polaritons in metamaterials via PIT, which are promising for chip-scale applications in information processing and transmission.

       PDF全文        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Amin Md Ziaul  

      摘要 + 此论文可免费阅读 (可能需要登录)

In erbium doped fiber amplifier (EDFA), erbium ions act as a three-level system. Therefore, much higher pump energy is required to achieve the population inversion in an erbium doped fiber (EDF). This higher pump energy requirement complicates the efficient design of an EDFA. However, efficient use of the pump power can improve the EDFA performance. The improved performance of an EDFA can be obtained by reducing the doping radius of the EDF. A smaller doping radius increases pump-dopant interactions and subsequently increases the pumpphoton conversion efficiency. Decreasing the doping radius allows a larger proportion of dopant ions, which are concentrated near the core, to interact with the highest pump intensity. However, decreasing the doping radius beyond a certain limit will bring the dopant ions much closer and introduce detrimental ionion interaction effects. In this paper, we show that an optimal doping radius in EDF can provide the best gain performance. Moreover, we have simulated the well-known numerical aperture (NA) effects on EDFA gain performance to support our claim.

       PDF全文        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Zhang Faxiang   Wang Chang   Zhang Xiaolei   Jiang Shaodong   Ni Jiasheng   Peng Gangding  

      摘要 + 此论文可免费阅读 (可能需要登录)

We present a highly sensitive fiber Bragg grating (FBG) based microphone with a flat response and static pressure equalization. A very high dynamic sensitivity is achieved by a pressure sensing structure based on a carbon fiber diaphragm. Static pressure equalization is realized by a balance structure with a capillary glass tube. The resonances of the sensor are suppressed by air damping structures, and a broadened flat response is achieved. Acoustic-solid interaction model was used to analyze the response characteristics of the microphone. A sensor prototype was produced and tested, and the results are well consistent with the design. The tested sensitivity was -10 dB re 1 pm/Pa from 10 Hz to 2.5 kHz, with a fluctuation of less than ±1.5 dB. Combined with the PGC (Phase Generated Carrier)-based coherent detection scheme, the microphone can achieve a sound resolution of mPa level. The static pressure sensitivity is measured to be -0.27 pm/atm, which is 100 dB lower than the dynamic sensitivity.

       PDF全文        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Hu Jinhua   Fu Jia   Liu Xiuhong   Ren DanPing   Zhao JiJun   Huang Yongqing  

      摘要 + 此论文可免费阅读 (可能需要登录)

We present a perfect graphene absorber with compound waveguide grating at near infrared. The analytical approach is mainly based on the coupled leaky mode theory, which turns the design of absorber to finding out the required leaky modes supported by the grating structure. Perfect absorption occurs only when the radiative loss of the leaky mode match the intrinsic absorption loss, which is also named as critical coupling condition. Furthermore, we also demonstrate that the critical coupling of the system can be robustly controlled, and the perfect absorption wavelength can be easily tuned by adjusting the parameters of compound waveguide grating.

       PDF全文        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Zhao Huijie   Xing Jian   Gu Xingfa   Jia Guorui  

      摘要 + 此论文可免费阅读 (可能需要登录)

A method for calculating atmospheric parameters measurement accuracy requirement based on polarized reflectance retrieval is proposed. The at-sensor polarization states with different atmospheric parameters content are simulated based on atmospheric radiative transfer model in order to select the key parameter affecting the polarization observation. Accuracy requirement of atmospheric parameters is derived through the polarized reflectance retrieval method. Experiment results show that retrieval accuracy of polarized reflectance of typical ground objects can be up to 90%. And the atmospheric parameters measurement accuracy requirement when the retrieval accuracy is more than 75% is derived.

       PDF全文        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Shi Junkai   Li Yao   Gao Shuyuan   Pan Yingling   Wang Guoming   Ji Rongyi   Zhou Weihu  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this paper, we report on a novel architecture for self-starting mode-locked figure-8 erbium-doped fiber laser using a loss-imbalanced nonlinear optical loop mirror (NOLM) with a bidirectional output coupler. All polarization-maintaining structure is adopted. A 2×2 optical coupler with splitting ratio of 50:50 is used at the junction to form a NOLM. Another coupler with splitting ratio of 10:90 is introduced at one end of fiber loop. The 10:90 coupler plays two roles: power attenuator and bidirectional output coupler. This architecture can achieve both large modulation depth and good self-starting ability simultaneously. With this architecture, the self-starting mode locking operation is achieved easily with pump power above threshold. The clockwise and counter-clockwise mode locked output powers are 10.1 mW and 10.3 mW, respectively, with the repetition rate of 3.63 MHz. The spectral bandwidths of the clockwise and counter-clockwise mode locked output pulses are 7.4 nm and 2.9 nm, and the corresponding pulse widths of the direct outputs are 530.6 fs and 1.55 ps, respectively.

       PDF全文        Chinese Optics Letters ，2018年第16卷第12期 pp.12      

Yu Yi   Gong Shaobo   Xu Min   Yuan Boda   Wu Yifan   Nie Lin   Ke Rui   Ye Minyou   Duan Xuru  

      摘要 + 此论文可免费阅读 (可能需要登录)

System validation and density fluctuation calibration of Phase Contrast Imaging (PCI) on HL-2A tokamakare presented. Signals from different channels show not only a pronounced modulation of incident laser beam induced by sound wave but also an excellent magnification and low image distortion of optics. Frequency-wavenumber spectrum is achieved by using two-dimensional Fourier transform of time series signals. Conversion relationship between detected signal amplitude and chord integral plasma density fluctuation is 2.35×1013m-2/mV, which promises a suitable signal level at the order of Volts of the PCI in typical HL-2A discharges.

       PDF全文        Chinese Optics Letters ，2018年第16卷第12期 pp.12      

Yu Lei   Zou Weiwen   Yang Guang   Li Xinwan   Chen Jianping  

      摘要 + 此论文可免费阅读 (可能需要登录)

This Letter theoretically and experimentally studies the response of photonic switching in a channel-interleaved photonic analog-to-digital converter (PADC) with high sampling rate and wide input frequency range. A figure of merit (FoM) is introduced to evaluate the switching response of the PADC when a dual-output Mach-Zehnder modulator (MZM) is served as the photonic switch to parallelize the sampled pulse train into two channels. After the optimization of the FoM and utilization of channel-mismatch compensation algorithm, the system bandwidth of PADC is expanded and the signal-to-distortion ratio (SDR) is enhanced.

       PDF全文        Chinese Optics Letters ，2018年第16卷第12期 pp.12      

Shi Qianqian   Zhang Yan   Wang KunPeng   Wang Chenglin   Zhao Peng  

      摘要 + 此论文可免费阅读 (可能需要登录)

The impact pendulum and torsion pendulum are mostly applied in impulse coupling experiments of high energy laser irradiation on space debris. It is difficult to achieve multi-pulse experiment and thus hard to analyze the multi-pulse impulse coupling effect. Here, we designed a new recoil impulse experimental measurement system of non-contact, multi-degree of freedom and multi-pulse irradiation is designed. The system used a low-pressure and low-temperature vacuum chamber to simulate the space environment, the pinning effect of magnetic levitation to achieve aluminum target suspension and high-speed cameras to record the displacement over time to calculate the impulse of target. Then the impulse coupling experiment of multi-pulse laser irradiation on aluminum target was performed. The result shows that the multi-pulse impulse coupling effect is not the linear accumulation of coupling results by every single pulse and mul-ti-pulse coefficient decreases with the increase of the number of pulses, and eventually stabilizes as the decrease getting smaller and smaller.

       PDF全文        Chinese Optics Letters ，2018年第16卷第12期 pp.12      

xia kaiye   Zhai Xiaohui   Xie Zhaoheng   Zhou Kun   Feng Yutao   Zhang Guangjie   Li Changhui  

      摘要 + 此论文可免费阅读 (可能需要登录)

Photoacoustic (PA) tomography (PAT) breaks the barrier for high resolution optical imaging in strong light scattering medium, having a great potential for both clinical implementation and small animal studies. However, many organs and tissues lack enough PA contrast or even hinder the propagation of PA waves. Therefore, it is challenging to interpret pure PAT images, especially PA three-dimensional (3D) images for deep tissues without enough structural information. To overcome this limitation, in this study, we integrated PAT with X-ray computed tomography (CT) in a standalone system. PAT provides optical contrast and CT gives anatomical information. We performed agar, tissue phantom and animal studies, and the results demonstrated that PAT/CT imaging system can provide accurate spatial registration of important complementary contrasts.

       PDF全文        Chinese Optics Letters ，2018年第16卷第12期 pp.12      

Zhang Yumin   Ren Yue   Dong Mingli   Meng Fanyong   zhu lianqing  

      摘要 + 此论文可免费阅读 (可能需要登录)

The Letter reports the thermal stability and strain response of Fabry-Perot (FP) cavity under different high temperatures. The FP cavity was made by thermal regeneration of two identical cascaded fiber Bragg gratings (FBGs). It is demonstrated that the FP cavity is capable of measuring temperature from 300 °C to 900 °C, with a temperature sensitivity of 15.97 pm/°C. The elongation of fiber was observed through the drifted Bragg wavelength at 700 °C or above when weight was loaded. The elongation was further inferred by the slight change in interference spectra of FP cavity at 900 °C.

       PDF全文        Chinese Optics Letters ，2018年第16卷第12期 pp.12      

yan lulu   zhang yanyan   tai zhaoyang   zhang pan   zhang xiaofei   guo wenge   Zhang Shougang   jiang haifeng  

      摘要 + 此论文可免费阅读 (可能需要登录)

By taking advantage of PDH frequency stabilization technique, frequency instability of most ultrastable laser systems is mainly limited by the thermal noise of the high reflection mirrors. In this letter, we demonstrate a proposal of making an ultrastable laser referenced to a multi-cavity, enabling a lower thermal noise limit due to the larger equivalent beam size. The multi-cavity consists of a few pairs of mirrors and a common spacer. One can stabilize the laser frequencies on these cavities, and average the laser frequencies with an optical synthesizer. In comparison with a single cavity system, relative frequency instability of the synthesized laser can be improved by a factor of the squire root of the cavity number (n). To proof this proposal, we perform an experiment to simulate a two-cavity system with two independent ultrastable lasers. These laser exhibits a frequency instability at 7E-16 for short term. Experimental results show that the relative frequency instability (Allan deviation of Δν/ν) of the synthesized laser is 5E-16 improved by a factor of √2 from a signal cavity stabilized laser. The measured noise effect of optical synthesizing is at E-17 level limited by synchronization of frequency counters, it reaches E-18 level while the lasers have lower noise level. This technique is compatible with other techniques; thus, it can gain a factor of √n on the frequency instability based on the current ultrastable lasers at the state-of-the-art level.

       PDF全文        Chinese Optics Letters ，2018年第16卷第12期 pp.12      

Barcelo-Chong Arturo   Estrada-Potrillo Brian   Canales-Benavides Arturo   Lopez Aguayo Servando  

      摘要 + 此论文可免费阅读 (可能需要登录)

We report the generation of asymmetric Mathieu optical lattices: invariant intensity optical profiles that can described by three parameters. The first one describes the amount of ellipticity, the second one takes into account the degree of asymmetry of the profile, and the third parameter denotes the angular position where is localized the respective asymmetry. We propose a simple angular spectrum to generate these nondiffracting beams, and we report how changes their distribution of power and orbital angular momentum in function of their ellipticity and degree of asymmetry. We confirm the existence of these invariant beams by propagation in an experimental setup.

       PDF全文        Chinese Optics Letters ，2018年第16卷第12期 pp.12      

Zhang Zhiming   Wei Wei   Tang Liqin   Yang Jie   Guo Jiewei   Ding Lei   Li Yigang  

      摘要 + 此论文可免费阅读 (可能需要登录)

An all fiber femtosecond vortex laser based on common fiber components is constructed. It can produce femtosecond orbital angular momentum modes whose pulse width of time is 398fs. The topological charge of output OAM modes from this setup can be adjusted among 0, +1, -1 easily while it is also easy to convert between continuous OAM modes and pulse OAM modes.

       PDF全文        Chinese Optics Letters ，2018年第16卷第11期 pp.11      

Cui Peng   Zhang Wentao   Song Ying  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this paper, a vertical-pendulum-based inclinometer based on Fiber Bragg Grating Fabry-Perot (FBG-FP) cavity is proposed. A low-damping rotation structure is used to reduce the mechanical frictions of the pendulum system and induce wavelength shift of FBG-FPs. We find that the sensitivity can be maximized by optimizing the parameters of the inclinometer. Using high-resolution demodulation system, a sensitivity of 179.9 pm/° and a resolution better than 2.0×10-2 ″ can be achieved. Experiments also show that the proposed inclinometer has good linearity and repeatability.

       PDF全文        Chinese Optics Letters ，2018年第16卷第11期 pp.11      

Deng Suhui   Xiao Yiping   Hu Jie   Chen Jianfang   Wang Yuhao   Liu Mingping  

      摘要 + 此论文可免费阅读 (可能需要登录)

The fluorescence from out-of-focus region excited by the side lobes of Bessel beam is the major concerns for the light-sheet fluorescence microscopy (LSFM) with Bessel beam plane illumination. Here, we propose a method of applying the subtractive imaging to overcome the limitation of the conventional LSFM with Bessel beam plane illumination. In the proposed method, the sample is imaged twice by line-scanning using the extended solid Bessel beam and the ring-like Bessel beam. By subtracting between the two images with similar out-of focus blur, the improved image quality with the suppression of the Bessel beam side lobes and enhanced sectioning ability with improved contrast is demonstrated.

       PDF全文        Chinese Optics Letters ，2018年第16卷第11期 pp.11      

Kang Kai   Zhang Liangliang   Wu Tong   Li Kai   Zhang Cunlin  

      摘要 + 此论文可免费阅读 (可能需要登录)

We report the terahertz (THz) wave generation from single color scheme modulated by pre-ionized air plasma via an orthogonal pumping geometry. It is found that the amplitude of the THz signal generated by the pump beam tends to decrease gradually with the increase of the modulation power. We believe that the ponderomotive force plays an important role in the process of the interaction between the pump beam and pre-ionization beam. The hydrostatic state of the electrostatic separation field caused by modulation beam will directly affect the generation efficiency of the THz wave. Our results contribute to further understanding of the theoretical mechanism and expanding of the practical applications of terahertz THz wave generation and modulation.

       PDF全文        Chinese Optics Letters ，2018年第16卷第11期 pp.11      

tianbo zhao   fenglan fan   ying liu   yifan hong   jinliang zang   guoguo kang   Tan Xiaodi  

      摘要 + 此论文可免费阅读 (可能需要登录)

A novel composite materials are synthesized by incorporating N-acryloylmorpholine (ACMO) in highly-concentrated phenanthrenequinone (PQ) doped poly-(methyl methacrylate) (PMMA). The photosensitizer concentration of PQ was increased from 0.7wt% to 1.8wt%. The doping of ACMO component results in a higher diffraction efficiency and photosensitivity than typical PQ/PMMA system. The enhanced performance of material may stem from the ACMO molecules which might open a new route for improving the holographic performance of PQ/PMMA photopolymer..

       PDF全文        Chinese Optics Letters ，2018年第16卷第11期 pp.11      

Xu Yongchi   Peng Huanfa   Guo Rui   Du Huayang   Hu Guoqing   Zhu Lixin   Chen Zhangyuan  

      摘要 + 此论文可免费阅读 (可能需要登录)

A wideband tunable optoelectronic oscillator (OEO) based on a tunable single-bandpass microwave photonic filter (MPF) and a recirculating delay line (RDL) is proposed and experimentally demonstrated. The MPF is formed by cascading a finite impulse response filter and an infinite impulse response filter, which can enhance the quality-factor of the MPF and suppress the side modes of the OEO. Frequency response of the tunable MPF is theoretically analyzed. By placing the MPF into OEO, tunable microwave signal from 10.3GHz to 26.7GHz and 100MHz-step tunability are experimentally demonstrated. The phase noise is -113 dBc/Hz@10kHz. The results agree well with the theory.

       PDF全文        Chinese Optics Letters ，2018年第16卷第11期 pp.11      

Zhang Xiaotong   Yuan Tingting   Yang Xinghua   Guan chunying   Yang Jun   Liu Zhihai   Deng Hongchang   Yuan Libo  

      摘要 + 此论文可免费阅读 (可能需要登录)

In-fiber integrated optics is an attempt to use silica fiber as a substrate, integrating various optical paths or optical components into a single fiber, to build a functional optical device or component, to realize a micro optical system, achieving various functions. In-fiber integrated optics is expected to be a new branch of photonics integration. This integration technique enables conve-nient light beams control and manipulation inside in one fiber. It also provides a research platform with micro and nano scale for interaction between lightwave and microfluidic maters. In this paper, we briefly summarize the main ideas and key technologies of the in-fiber integrated optics by series integration examples.

       PDF全文        Chinese Optics Letters ，2018年第16卷第11期 pp.11      

Luo Binbin   Lu Huafeng   Shi Shenghui   Zhao Mingfu   Lu Jiao   Wang Yajie   Wang Xing  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate a fiber refractive index (RI) sensor based on excessively tilted fiber grating (ExTFG) immobilized by large-size plasmonic gold nanosells(GNSs). The GNSs are covalently linked on ExTFG surface. Experimental results demonstrate that both the intensity of transverse magnetic (TM) and transverse electric (TE) mode of ExTFG are significantly modulated by the localized surface Plasmon resonance (LSPR) of GNSs due to the wide-range absorption band. The wavelength RI sensitivities of TM and TE mode in the low RI range of 1.333~1.379 are improved by ~25% and ~14% after GNSs immobilization, respectively, and the intensity RI sensitivities are ~599%/RIU and ~486%/RIU, respectively.

       PDF全文        Chinese Optics Letters ，2018年第16卷第10期 pp.10      

Liu Jingsong   Cheng Qiyuan   Yue Daguang   Zhou Xucong   Meng Qingtian  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this paper, we study the molecular alignment and orientation driven by two elliptically polarized laser pulses. It is shown that the field-free molecular alignment can be achieved in a three-dimensional(3D) case while the field-free molecular orientation only along the x and y directions, and that the field-free alignment and orientation along different axes is related to the populations of the rotational states. It is demonstrated that changing the elliptic parameter is efficient for controlling both in-pulse and post-pulse molecular alignment and orientation. And the delay time also has an influence on the field-free molecular alignment and orientation.

       PDF全文        Chinese Optics Letters ，2018年第16卷第10期 pp.10      

Sun Xiaoyan   Cui Dongmei   Hu Youwang   Chu Dong kai   Chen Guowei   Yu Jinlong   Zhou Jianhang   Duan Ji'an  

      摘要 + 此论文可免费阅读 (可能需要登录)

In order to improve the morphology of microchannels fabricated by femtosecond laser ablation, the thermal process was introduced into the post-treatment processing. It was found that thermal process can not only decrease the roughness but also the width and depth of the microchannel. The change rates of width, depth, and roughness of microchannel increases with processing temperature. When we prolong the time of constant temperature, the change rate of width decreases at beginning, and then it tends to be stable. However, the change rates of depth and roughness increase, and then they tend to be stable. In this paper, we discuss the reasons of the above phenomena.

       PDF全文        Chinese Optics Letters ，2018年第16卷第10期 pp.10      

Xing Jianfei   Wen Jianxiang   Wang jie   pang fufei   Chen Zhenyi   Liu Yunqi   Wang Tingyun  

      摘要 + 此论文可免费阅读 (可能需要登录)

A few-mode erbium doped fiber (FM-EDF) is fabricated using MCVD in combination with liquid solution, and the core and cladding diameters of the fiber are approximately 19.44 and 124.12 μm, respectively. The refractive index difference is 0.98%, numerical aperture (NA) is 0.17, and normalized cut-off frequency V at 1550 nm is 6.81. Therefore, it is a five-mode fiber, and can be used as gain medium of higher order mode. Furthermore, a long period of fiber grating (LPFG) is fabricated, which can convert LP01 mode to LP11 mode, and its conversion efficiency is up to 99%. And the first order orbital angular momentum (OAM) is also generated by combining LPFG and polarization controller (PC). Then, an all-fiber amplification system based on FM-EDF and LPFG, for LP11 mode and first order OAM beams, is built up. Its On-Off gain of LP11 mode beam is 37.2dB at 1521.2 nm. And the variation, which transverse mode field intensity of first order OAM is increased with the increasing of pumping power, is obvious. These show that both LP11 mode and first order OAM beams are amplified in the all-fiber amplification system. This is a novel all-fiber amplification, which can be used in the optical communication fields.

       PDF全文        Chinese Optics Letters ，2018年第16卷第10期 pp.10      

Ge Xulei   Yuan Xiaohui   Yuan Fang   Wei Wenqing   Yang Su   Liu Feng   chen min   Zhao Li   Sheng Zhengming   Zhang Jie  

      摘要 + 此论文可免费阅读 (可能需要登录)

The temporal profiles of high-power short-pulse lasers reflected from self-induced plasma mirrors (PM) were measured with high temporal resolution in the sub-picosecond window. The leading front shape of the laser pulse is found to depend sensitively on the laser fluence on PM surface. The spectral modulation is found to play a key role in pulse profile shaping. Our finding will extend our knowledge on properly using plasma mirror.

       PDF全文        Chinese Optics Letters ，2018年第16卷第10期 pp.10      

Zhang Li   Li Fangye   Wang Shuai   Wang Qi   Luan Kairan   Chen Xi   liu xiuhuan   Qiu Lingying   Chen Zhanguo   Zhao Ji-Hong   Hou Lixin   Gao Yanjun   jia Gang  

      摘要 + 此论文可免费阅读 (可能需要登录)

In this paper, we have demonstrated significant electric field induced (EFI) optical rectification (OR) effects existing in the surface layers of germanium (Ge), and measured the distributions of EFI OR signals along the normal directions of surface layers of Ge samples. Based on the experimental results, the ratios of the two effective second-order susceptibility componentsχ_zzz^((2eff))/χ_zxx^((2eff)) for Ge(001) , Ge(110) and Ge(111) surface layers can be estimated to be about 0.92, 0.91, and 1.07, respectively. The results indicated that the EFI OR can be used for analyzing the properties on surface layers of Ge, which has potential applications in Ge photonics and optoelectronics.

       PDF全文        Chinese Optics Letters ，2018年第16卷第10期 pp.10      

zhou linjie   Wang Xinyi   Lu Liangjun   Chen Jianping  

      摘要 + 此论文可免费阅读 (可能需要登录)

Optical delay lines (ODLs) are one of the key enabling components in photonic integrated circuits and systems. They are widely used in time-division multiplexing, optical signal synchronization and buffering, microwave signal processing, beam forming and steering etc. The development of integrated photonics pushes forward the miniaturization of ODLs, offering improved performances in terms of stability, tuning speed and power consumption. The integrated ODLs can be implemented using various structures, such as single or coupled resonators, gratings, photonic crystals, multi-paths switchable structures, recirculating loop structures. The delay tuning in ODLs is enabled by either changing the group refractive index of the waveguide or changing the length of the optical path. This paper reviews the recent development of integrated ODLs, with a focus on their abundant applications and flexible implementations. The challenges and potentials of each type of ODLs are pointed out.

       PDF全文        Chinese Optics Letters ，2018年第16卷第10期 pp.10      

Liu Jiao   Liu Yang   Tang Xiaojun   Wang Chao  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate a high-efficiency and high-power quasi-three-level laser based on a trapezoidal composite slab architecture with a 270 μm-thick Yb-doping surface. The design of surface-doped slab architecture, temperature effects, laser oscillator model and laser oscillator experiments with surface-doped slab as laser host media have been presented. By theoretical calculation, the temperature rise in the surface-doped slab is only seventh of that is in the bulk doped slab at the same maximum pump power of 30 kW. Finally, in the laser oscillator experiments, the output energy of 21.6 J is obtained when the pump energy is 48 J with the repetition rate of 5 Hz and pulse width of 1 ms. The optical-optical efficiency is 45%.

       PDF全文        Chinese Optics Letters ，2018年第16卷第10期 pp.10      

He Xi   Liu Cheng   Zhu Jianqiang  

      摘要 + 此论文可免费阅读 (可能需要登录)

We propose a novel on-line beam diagnostic method based on beam splitting single-shot phase retrieval. The incident beam to be measured is diffracted into many replicas by a Dammann grating and then propagate through a weakly scattering phase plate with known structure, the exiting beams propagate along their original direction and form an array of diffraction pattern on the detector plane. By applying the intensity of diffraction patterns into an iterative algorithm and calculating between grating plane, weakly scattering plane, and the detector plane, the complex field of incident beam can be reconstructed rapidly, the feasibility of this method is verified experimentally with wavelength of 1053nm and 632.8nm.

       PDF全文        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

Guo Xin   Ding Jinbin   Zhou Yi   Wang Yu  

      摘要 + 此论文可免费阅读 (可能需要登录)

The ablation of Sintered Silicon Carbide Ceramics by ArF excimer laser were studied. Three zones are generated: the ablation zone presented molten morphology and composed by Si and C phase; the condensation zone formed by vaporized SiC; the oxidation zone showed the characteristics of thermal oxidation. The ablation depth and oxidation range increase linearly with fluence and pulses within 0.5-4J/cm2, but the normalized ablation efficiency is constant (3.60±0.60). The theoretical photochemical ablation depth supplies 25% of the total depth at 1J/cm2 but decreases to 16% at 4J/cm2. The ablation is dominated by photothermal effect and conforms to thermal evaporation mechanism.

       PDF全文        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

Wang Kejia   Gu Xinyang   Zhang Zhenwei   Yang Zhengang   Liu Jinsong   Wang Shenglie  

      摘要 + 此论文可免费阅读 (可能需要登录)

Previous research shows that few-cycle laser (FCL) pulses with low energy and without a bias field can be used to coherently detect terahertz (THz) pulses. As we know, it is very difficult to stabilize the carrier envelop phase (CEP) of FCL pulses, i.e. there are some random fluctuations for the CEP. Here we theoretically investigate the influence of such instability on the accuracy of THz detection. Our results show that although there is an optimum CEP for THz detection, the fluctuations of CEP will lead to terrible thorns on the detected THz waveform. In order to solve this problem, we propose an approach via using two few-cycle laser pulses with opposite CEPs, i.e. their CEPs are differed by <i>π</i> .

       PDF全文        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

Sulaiman Abdul Hadi   Abdul kadir Muhammad Zamzuri   YUSOFF NELIDYA   Cholan Noran Azizan   Abdullah Fairuz   Abas Ahmad Fauzi   Alresheedi Mohammed Thamer   Adzir Mahdi Mohd  

      摘要 + 此论文可免费阅读 (可能需要登录)

We demonstrate a broad bandwidth multiwavelength laser based on a bidirectional Lyot filter and semiconductor optical amplifier with a mechanism of intensity dependent loss as the flatness agent. A wide bandwidth of multiwavelength spectrum of 32.9 nm within 5 dB uniformity is obtained under optimized polarization parameters. For this case, the number of generated lasing lines is 329 with a fixed wavelength separation of 0.1 nm. The power stability of this multiwavelength laser is less than 1.35 dB within 200 minutes time frame. This shows that the bidirectional Lyot filter provides an alternative option for multiwavelength generation in laser systems.

       PDF全文        Chinese Optics Letters ，2018年第16卷第9期 pp.09      

zhou daibing   Zhao Lingjuan  

      摘要 + 此论文可免费阅读 (可能需要登录)

We report 20 Gb/s transmission of 4-level pulse amplitude modulation (PAM) signal using a directly modulated tunable distributed Bragg reflector (DBR) laser, Transmission distance over 20 km was achieved without using optical amplifiers and optical dispersion compensation modules. A wavelength tuning range of 11.5 nm and the 3-dB bandwidth greater than 10 GHz over the entire wavelength tuning range was obtained.

       PDF全文        Chinese Optics Letters ，2018年第16卷第9期 pp.09