ZOU Xihua   Li Peixuan   Pan Wei   Yan Lianshan  

      摘要 + ：(浏览：5次) | 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 (下载：2)        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 + ：(浏览：6次) | 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 (下载：3)        Chinese Optics Letters ，2019年第17卷第2期 pp.02      

Yuan Shuai   Wang Lirong   Liu Fengjiang   Zhou Fengquan   Li Min   Xu Hui   Nie Yuan   Nan Junyi   Zeng Heping  

      摘要 + ：(浏览：3次) | 此论文可免费阅读 (可能需要登录)

We report a universal approach based on the surface plasmon resonances (SPRs) attained in filamentation in water doped with gold nanoparticles for enhancing the nonlinear refractive index. The filament-induced supercontinuum spectrum in water overlaps with SPRs of gold nanospheres, which further leads to a modification on the Kerr nonlinear refraction index. In our experiment, the measured nonlinear refractive index (n2) in water doped with gold nanoparticles increases six times as compared with that in pure water. Such enhancement may be useful for filament-induced nonlinear applications with modest incident intensity.

       PDF全文 (下载：0)        Chinese Optics Letters ，2019年第17卷第3期 pp.03      

Li Miao   Chen Gui   Leng Jinyong   Chen Jinbao   Li Jinyan  

      摘要 + ：(浏览：6次) | 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 (下载：4)        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 + ：(浏览：4次) | 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 (下载：1)        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 + ：(浏览：2次) | 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 (下载：0)        Chinese Optics Letters ，2019年第17卷第3期 pp.03      

Khan Humayun   Haneef Muhammad   Bakhtawar Bakhtawar  

      摘要 + ：(浏览：12次) | 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 (下载：3)        Chinese Optics Letters ，2019年第17卷第3期 pp.03      

Fu Zhijie   Wang Qiyu   Wang Zhaoying   Bin Wu   Cheng Bing   Lin Qiang  

      摘要 + ：(浏览：13次) | 此论文可免费阅读 (可能需要登录)

The first Asia-Pacific Comparison of Absolute Gravimeters (APMP.M.G-K1) was organized by the National Institute of Metrology (NIM) of China during from December 21st, 2015 to March 25th, 2016 in Changping, Beijing. Our compact cold atom gravimeter (CCAG) was transported from Hangzhou to Beijing with a long distance of about 1200 km to participate in this comparison. The CCAG is the only one which based on the principle of atom interferometry among all the instruments. The absolute gravity in the indicated three test sites has been measured as requested by the organizer. The sensitivity of our CCAG is estimated to be 90 μGal/√Hz even when the measurements are carried out without any vibration isolation. Besides, the accuracy of this gravimeter has been evaluated to be about 19 μGal by considering the significant system errors. Our results show a good agreement with the given reference value.

       PDF全文 (下载：1)        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

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

      摘要 + ：(浏览：18次) | 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 (下载：5)        Chinese Optics Letters ，2019年第17卷第2期 pp.02      

Jia Yuechen   Chen Feng  

      摘要 + ：(浏览：28次) | 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 (下载：19)        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

He Zhiwen   Zheng Yang   Liu Hongyan   Li Mingkun   Lu Hua   Zhang Heze   Feng Qingliang   Mao Dong  

      摘要 + ：(浏览：28次) | 此论文可免费阅读 (可能需要登录)

We demonstrate an all-fiber Q-switched cylindrical vector laser based on a black phosphorus saturable absorber and a transverse mode converter. The saturable absorber is prepared by incorporating the polyvinyl alcohol with anti-oxidized black phosphorus nanosheets exfoliated in aqueous poly dimethyldiallyl ammonium chloride solutions. The mode converter is composed of tapered two-mode fiber and single-mode fiber, and it can excite switchable azimuthally and radially polarized beams by modulating the input polarization. By enhancing the pump power from 64.68 mW to 174.82 mW, the repetition rate of Q-switched azimuthally/radially polarized laser enlarges from 16.72/19.25 kHz to 30.71/37.82 kHz.

       PDF全文 (下载：24)        Chinese Optics Letters ，2019年第17卷第2期 pp.02      

wang cong   Peng Qian   Xin Linlin   Liu Jie  

      摘要 + ：(浏览：14次) | 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 (下载：1)        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 + ：(浏览：19次) | 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 (下载：3)        Chinese Optics Letters ，2019年第17卷第2期 pp.02      

Cai Yuancheng   Ling Yun   Gao Xiang   Xu Bo   Qiu Kun  

      摘要 + ：(浏览：14次) | 此论文可免费阅读 (可能需要登录)

We propose and investigate the use of Kramers–Kronig (KK) receiver in single sideband orthogonal frequency division multiplexing radio over fiber (SSB-OFDM-RoF) link based on optical remote heterodyne solution. This scheme is effective in eliminating the signal-to-signal beating interference (SSBI) introduced by square-law detection of photo-detector (PD) in SSB-OFDM-RoF link. We extensively studied the influences of different carrier-to-signal power ratios (CSPRs), laser linewidths and transmission distances on our proposed scheme. It is proved that the KK-based receiver can reduce optimal CSPR by more than 5 dB and provide about 1.1 dB gain over the conventional mixer-based receiver scheme with CSPR of 11 dB after 75 km fiber transmission.

       PDF全文 (下载：3)        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Li Jiakun   Feng Qibo   Bao Chuanchen   Zhang Bin  

      摘要 + ：(浏览：12次) | 此论文可免费阅读 (可能需要登录)

We report a method for simultaneously and directly measuring all the six-degrees-of-freedom motion errors of a rotary axis. Such method combines the principles of laser interferometry and laser collimation measurement. One reference rotary axis and two retro-reflectors are used to achieve simultaneous sensitivity to all six errors in a full-circle measuring range. As no separation models are required, our method is capable to dynamically measure these errors in real time and conveniently determine the origin of the errors. An automatic measuring device was built. The effectiveness of our method is experimentally demonstrated.

       PDF全文 (下载：6)        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Li Chun   Leng Yuxin   Huo Jinjin  

      摘要 + ：(浏览：18次) | 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 (下载：7)        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Kharmyssov Chingis   Ko Match   Kim Jong R.  

      摘要 + ：(浏览：23次) | 此论文可免费阅读 (可能需要登录)

We propose a fast and accurate automated algorithm to segment retinal pigment epithelium and internal limiting membrane layer from spectral-domain optical coherence tomography (SDOCT) B-scans images. A hybrid algorithm, which combines intensity thresholding and graph-based algorithms, was used to process and analyze SDOCT radial scans (a hundred and twenty B-scans) images obtained from twenty patients. The relative difference in position of the layers segmented by the proposed hybrid algorithm and by clinical expert was 1.49% ± 0.01%. The processing time of the hybrid algorithm was 9.3 s for six B-scans. The Dice’s coefficient of the hybrid algorithm was 96.7%±1.6%. The proposed hybrid algorithm for the segmentation of SDOCT images had good agreement with manual segmentation and reduced processing time.

       PDF全文 (下载：4)        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Zhou Yong   Gao Panyun   Zhang Xiu   Wang Peng   Chen Liang   Gao Weiqing  

      摘要 + ：(浏览：28次) | 此论文可免费阅读 (可能需要登录)

We propose a switchable multi-wavelength erbium-doped fiber laser based on a four-mode fiber Bragg grating. The four-mode fiber Bragg grating is fabricated in a hydrogen pre-loaded fiber by the phase mask method which can support four linearly polarized modes around 1550 nm. The five operation wavelengths are at 1547.5, 1546.8, 1546.0, 1545.1 and 1544.2 nm, respectively. Through adjusting the polarization state and the lateral offset coupling in cavity, the laser can be switched into the operation state of single, dual or triple wavelengths. The proposed laser has the advantages of simple configuration, stable operation and easy adjustment.

       PDF全文 (下载：7)        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Meng Xin   Yang Zhongming   Du Jinyu   Fan Guobin  

      摘要 + ：(浏览：24次) | 此论文可免费阅读 (可能需要登录)

A double-pass grating imaging spectrometer is proposed and demonstrated. The traditional entrance slit is replaced by a middle reflective slit which is used as a spectral filter rather than a spatial filter. The light from the scene passes through the same dispersive grating twice. The full image of the scene can be obtained with snapshot. Therefore the stripe noise and images distortion caused by image mosaicking can be eliminated. Besides, the target is easier to be captured and focused just like using a camera. This method can be used to obtain clearer spectral images of the scene conveniently and quickly.

       PDF全文 (下载：4)        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Bai Zhengyang   Zhang Qi   Huang Guoxiang  

      摘要 + ：(浏览：38次) | 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 (下载：10)        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Ma Huiliang   Jia Xin-Hong   Lin Kai   Xu Cong  

      摘要 + ：(浏览：48次) | 此论文可免费阅读 (可能需要登录)

For Brillouin optical time-domain analysis (BOTDA) based on distributed Brillouin amplification (DBA), constant Brillouin response achieved by the exponentially variable bandwidth/intensity pump modulation suffers from the much lower pumping efficiency for long-range sensing, which counterbalances the merit of DBA. In this letter, pump modulation by multiple constant bandwidths was proposed and demonstrated. ~98.9 km sensing with ~5 m spatial resolution and no use of optical pulse coding (OPC) was achieved by ~8 dBm Brillouin pump, which is lower by ~9 dB in theory by comparison with exponentially increased bandwidth modulation. Compared with traditional DBA-BOTDA, signal-to-noise ratio (SNR) enhancement with > 4.6 dB was obtained. The flattened standard deviation (STD) of Brillouin frequency shift (BFS) (less than ~2 MHz) along the whole fiber was demonstrated.

       PDF全文 (下载：22)        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Amin Md Ziaul  

      摘要 + ：(浏览：29次) | 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 (下载：7)        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Zhang Zexia   Chang Jun   Ren Hongxi   Fan Kaiyuan  

      摘要 + ：(浏览：38次) | 此论文可免费阅读 (可能需要登录)

This letter proposes a snapshot imaging spectrometer, which obtains the spectral information and spatial information in one “shot”. The device proposed can achieve the datacube size of 21*29*40 between the waveband 400-800nm. The core element of this system is the microlens array, which contains 60*60 microlens in a square arrangement, each microlens has an aperture of 125μmX125μm, and F number is 15. The microlens array is mounted in a rotation mount which provides 360° of rotation around the optical axis to maximize the spectral resolution. The final resolution of the system is about 10nm.

       PDF全文 (下载：9)        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 + ：(浏览：40次) | 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 (下载：7)        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Diao Zhihui   Kong L   Yan Junliang   Guo Junda   Liu Xiaofeng   Xuan Li   Yu Lei  

      摘要 + ：(浏览：42次) | 此论文可免费阅读 (可能需要登录)

In this letter, we present an electrically tunable holographic waveguide display (HWD) based on two slanted holographic polymer dispersed liquid crystal (HPDLC) gratings. Experimental results show that a see-through effect is obtained in the HWD that both the display light from HWD and the ambient light can be clearly seen simultaneously. By applying an external electric field, the output intensity of the display light can be modulated, which is attributed to the field-induced rotation of the liquid crystal molecules in the two HPDLC gratings. We also show that this electrically tunable performance enables the HWD to adapt to different ambient light condition. This study provides some ideas towards the development of HWD and its application in augmented reality.

       PDF全文 (下载：7)        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 + ：(浏览：42次) | 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 (下载：11)        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Sun Fangyuan   Zhao Yufei   Shu Shili   Hou Guanyu   Lu Huanyu   Zhang Xin   Wang Lijie   Tian Sicong   Tong Cunzhu   Wang Lijun  

      摘要 + ：(浏览：23次) | 此论文可免费阅读 (可能需要登录)

A modified spectral beam combining (SBC) approach based on double asymmetrical filters was proposed. By using this scheme, the high-order lateral modes at the edge of the far-field pattern can be suppressed in the external cavity, and the beam quality in the slow-axis direction was improved from 16.1 to 13.4 compared to the conventional SBC. In the meanwhile, the electrical-to-optical efficiency from the modified SBC was more than 40% with an output power of 34.1 W, which was similar to that of the conventional SBC.

       PDF全文 (下载：13)        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Li Guiyun   Gu Liyuan   Hu Jingpei   Zhu Linglin   zeng Aijun   Huang Huijie  

      摘要 + ：(浏览：41次) | 此论文可免费阅读 (可能需要登录)

Single layer graphene deposited on the metal substrate can hardly be imaged by the optical microscope. In this paper, a large field-of-view imaging ellipsometer is introduced to image the single layer graphene which is deposited on metal substrate. By adjusting the polarizer and the analyzer of imaging ellipsometer, the light reflected from surfaces of either single layer graphene or Au film substrate can extinguish, respectively. Thus the single layer graphene can be imaged correspondingly under brightfield or darkfield imaging mode. The method can be applied to imaging large-area graphene on metal substrate.

       PDF全文 (下载：7)        Chinese Optics Letters ，2019年第17卷第1期 pp.01      

Zhao Huijie   Xing Jian   Gu Xingfa   Jia Guorui  

      摘要 + ：(浏览：25次) | 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 (下载：7)        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 + ：(浏览：59次) | 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 (下载：8)        Chinese Optics Letters ，2018年第16卷第12期 pp.12