Journals >Laser & Optoelectronics Progress
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2016
Volume: 53 Issue 12
38 Article(s)
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Atmospheric Optics and Oceanic Optics
Experimental Study of Impact of High Power Laser Irradiation on Compensation Ability of Deformable Mirrors
Feng Fei, Wei Binbin, Liu Wenguang, Jiang Zongfu, and Zhou Qiong
Continuous faceplate discrete actuator deformable mirror (CFDA-DM) is the most important device in adaptive optics. In high power laser systems, this kind of deformable mirror (DM) is apt to produce thermal deformation, which can seriously affect the compensation ability of DM and the output beam quality. Experimental Continuous faceplate discrete actuator deformable mirror (CFDA-DM) is the most important device in adaptive optics. In high power laser systems, this kind of deformable mirror (DM) is apt to produce thermal deformation, which can seriously affect the compensation ability of DM and the output beam quality. Experimental platform is set up to study DM thermal deformation. In the experiment, when DM is continuously irradiated by 2.5 kW laser for 130 s, the peak-to-valley value (dPV) of wavefront increases from 0.0806λ (before irradiation) to 0.5423λ, the higher order aberration of faceplate is 0.1220λ, and the low order aberration is mainly defocus and astigmatism. After dPV of a zero degree astigmatism is compensated from 0.4853λ to 0.0707λ, DM is irradiated by 2.5 kW laser for 180 s again. In consequence, the dPV of wavefront increases from 0.0707λ to 0.7548λ, and the higher order aberration of wavefront is 0.2487λ. The above results show that the thermal deformation does not only lead to lower order aberration, but also produce higher order aberration, which cannot be compensated by DM itself. The higher order aberration is the key factor that influences the output beam quality of high power laser systems..
Laser & Optoelectronics Progress
- Publication Date: Dec. 06, 2016
- Vol. 53, Issue 12, 120101 (2016)
Inversion of Seawater Optical Communication Channel Characteristics Based on Remote Sensing Data
Ao Jun, Liu Jingqiu, and Ma Chunbo
Laser communication is a new hot spot in underwater wireless communication. It′s the key in channel research to evaluate the laser transmission attenuation under seawater environment accurately. A new remote sensing inversion algorithm is proposed by synthesizing the existed QAA-RGR (Quasi-Analytical Algorithm Red-GreeLaser communication is a new hot spot in underwater wireless communication. It′s the key in channel research to evaluate the laser transmission attenuation under seawater environment accurately. A new remote sensing inversion algorithm is proposed by synthesizing the existed QAA-RGR (Quasi-Analytical Algorithm Red-Green-Bands-Ratio) remote sensing inversion algorithm and the national satellite ocean application service (NSOAS) model, which can evaluate the attenuation coefficient spectra based on moderate-resolution imaging spectroradiometer (MODIS) land bands data directly. Compared the absorption coefficient spectrum and scattering coefficient spectrum, which is estimated by inversion algorithm with MODIS L2 level data, the feasibility of the inversion algorithm is verified. It is important to analysis and understand the optical properties of seawater at coastal areas dynamically..
Laser & Optoelectronics Progress
- Publication Date: Nov. 13, 2016
- Vol. 53, Issue 12, 120102 (2016)
Calculation of Solar Spatial Position Based on Rayleigh Atmosphere Polarization Pattern
Yan Hao, Tang Jun, Zhang Nan, Yang Jiangtao, Wang Chenguang, Liang Jianqi, Qian Kun, and Wu Dajin
Solar spatial position is a very important navigation information in the field of navigation by using atmospheric polarization pattern. And how to get the solar spatial position is very important in navigation. A method based on Rayleigh atmosphere polarization pattern and K-means clustering algorithm is introduced to Solar spatial position is a very important navigation information in the field of navigation by using atmospheric polarization pattern. And how to get the solar spatial position is very important in navigation. A method based on Rayleigh atmosphere polarization pattern and K-means clustering algorithm is introduced to calculate the solar spatial position. The atmospheric polarized model of skylight is established on the basis of the Rayleigh scattering theory of atmosphere. According to the basic regularities of atmospheric polarization pattern, data of the polarization (DOP) are analyzed by the method of K-means clustering algorithm. The problem of solving position of the sun is transformed into the problem of solving the center of K-means cluster. Finally, the simulation experiment and practical experiment are carried out to verify the algorithm. The experiment shows that, at different times of the same day under clear weather, the errors of the solar position and altitude angle are all less than 0.01°. The algorithm error is smooth, and the relative error can reach higher precision. The solar spatial space can be effectively solved by atmospheric polarization pattern..
Laser & Optoelectronics Progress
- Publication Date: Nov. 20, 2016
- Vol. 53, Issue 12, 120103 (2016)
Performance Analysis of Underwater Optical Communication Based on LDPC and PPM
Du Jinsong, Zhou Tianhua, Chen Weibiao, and Hu Fangren
Because the signal attenuation is great in sea channel so as to seriously impact on the performance of communication system, an excellent error correcting code is necessary to reduce the error rate of data transmission in underwater optical communication. A system model of underwater optical communication is establisheBecause the signal attenuation is great in sea channel so as to seriously impact on the performance of communication system, an excellent error correcting code is necessary to reduce the error rate of data transmission in underwater optical communication. A system model of underwater optical communication is established by combining low density parity-check code with pulse position modulation. A simplified soft demodulation based on the general PPM soft demodulation is used to reduce the complexity of the algorithm, which is convenient for hardware implementation. What's more, the simplified soft demodulation method is very suitable for the extraction of soft information in sea channel because it does not need the detailed features of channel. The error performance between the general method and simplified method is analyzed by using Matlab software. According to the simulation results, the system code gain by using simplified method is decreased because of the simplified extraction of soft information, but it is still higher than code gain of the uncoded system. When PPM order is lower, the performance by using simplified method is even superior to that by Solomon Reed code. On the whole, the scheme of the simplified soft demodulation based on the combination of LDPC and PPM is very suitable for underwater optical communication in huge ranges of applications..
Laser & Optoelectronics Progress
- Publication Date: Dec. 06, 2016
- Vol. 53, Issue 12, 120605 (2016)
Diffraction and Gratings
Influence of Sub-Wavelength Grating on Micro-Electro-Mechanical System Wavelength Tunable Vertical Cavity Surface Emitting Laser
Jiang Xiaowei
The anti-reflection sub-wavelength gratings are placed at the inner cavity of the micro-electro-mechanical system (MEMS) wavelength tunable vertical cavity surface emitting laser (VCSEL), top surface and bottom surface of the top distributed Bragg reflectors(DBR), respectively. The effects of the positions on the wavelThe anti-reflection sub-wavelength gratings are placed at the inner cavity of the micro-electro-mechanical system (MEMS) wavelength tunable vertical cavity surface emitting laser (VCSEL), top surface and bottom surface of the top distributed Bragg reflectors(DBR), respectively. The effects of the positions on the wavelength tuning range, the standing wave field and the resonant cavity wavelength are analyzed. The simulation results demonstrate that when the sub-wavelength grating is placed in the inner cavity of the MEMS wavelength tunable VCSEL, the largest wavelength tuning range can be achieved, which can reach 54 nm, while the largest wavelength tuning ranges for the other two structures are 40 nm and 33 nm, respectively. It is known by analysis of the standing wave field that the active region energy is 0.36% of the total energy when the sub-wavelength grating is set on the top surface of the top DBR, while it is 0.08% and 0.02% when the sub-wavelength gratings are set in the inner cavity and on the bottom surface of the top DBR. In addition, the resonant cavity wavelength with the corresponding to the transverse electric (TE) and transverse magnetic (TM) polarizations appears the separation of 8.3 nm and 10.1 nm when the sub-wavelength gratings are put in the inner cavity and on the bottom surface of the top DBR, while it has not separation for the top surface of the top DBR. Thus, the polarization stable principles of the three structures are different..
Laser & Optoelectronics Progress
- Publication Date: Nov. 15, 2016
- Vol. 53, Issue 12, 120501 (2016)
Fiber Optics and Optical Communications
Real-Time Signal Polarization Compensation Method for Periscopic Laser Communication Terminal
Jiang Lun, Wang Chao, An Yan, Liu Zhuang, Li Yingchao, and Zhang Lizhong
Aiming at the problem of low mixing efficiency caused by unstable signal polarization states because of moving reflector in the periscopic laser communication terminal, a real-time polarization compensation method based on rotating waveplates is presented, by which 45° linear-polarized receiving signal light is keAiming at the problem of low mixing efficiency caused by unstable signal polarization states because of moving reflector in the periscopic laser communication terminal, a real-time polarization compensation method based on rotating waveplates is presented, by which 45° linear-polarized receiving signal light is kept so as to improve the system mixing efficiency. The geometric model of periscopic scanner is established, and based on it, the polarization transmission characteristics are analyzed by three-dimensional polarization tracks method, and the system polarization transmission matrix is obtained as well. The polarization states of output beams under different azimuths and pitch angles are given and the connection between rotation angles of polarization compensation elements (1/4 waveplate and 1/2 waveplate) and azimuths and pitch angles of periscopic scanner is established. The effect of the waveplates rotating anlgle errors on the polarization state of output light is analyzed..
Laser & Optoelectronics Progress
- Publication Date: Dec. 06, 2016
- Vol. 53, Issue 12, 120601 (2016)
Scale Factor Error During Startup Process of Fiber Optic Gyro
Wang Xiaxiao, Wei Liangyong, Wang Xiang, and Li Chuansheng
In modern war weapons and inertial navigation systems, the fiber optic gyro (FOG) is required to start quickly. The effect of temperature on the scale factor error in the process of FOG startup is studied. The FOG startup time is closely related to the output performance of a superluminescent diode (SLD). The effect ofIn modern war weapons and inertial navigation systems, the fiber optic gyro (FOG) is required to start quickly. The effect of temperature on the scale factor error in the process of FOG startup is studied. The FOG startup time is closely related to the output performance of a superluminescent diode (SLD). The effect of the SLD output wavelength on the FOG scale factor error is studied, and the theoretical results are analyzed in simulation and verified experimentally. The results show that the change of SLD output wavelength caused by the temperature change seriously affect the scale factor error in the process of FOG startup. The larger the temperature change is, the larger the scale factor error in the process of FOG startup is. The maximum scale factor error is up to 0.048, 0.0144, 0.025 when the temperature is -20, 50, 70 ℃, and the startup time is up to 6, 7, 11 s respectively..
Laser & Optoelectronics Progress
- Publication Date: Nov. 18, 2016
- Vol. 53, Issue 12, 120602 (2016)
Integrated Technology of Communication and Velocity Measurement in Satellite Coherent Optical Communication
Xu Yunxiang, Xu Mengmeng, Sun Jianfeng, Wu Bin, and Wang Bo
To deal with the difficulty in realizing optical phase-locked loop (OPLL) and shorten capture time in satellites coherent light communication, a heterodyne detection and digital signal processor (DSP) based integrated method of communication and velocity measurement is proposed, which uses the frequency shift estimatioTo deal with the difficulty in realizing optical phase-locked loop (OPLL) and shorten capture time in satellites coherent light communication, a heterodyne detection and digital signal processor (DSP) based integrated method of communication and velocity measurement is proposed, which uses the frequency shift estimation and phase recovery technology in optical fiber communication. Principle and feasibility of the method are analyzed theoretically and verified experimentally. Simulation results show that when the received power is higher than -48.14 dBm under the mode of communication, the bit error rate (BER) of the system is better than 10-4, and when the signal noise ratio (SNR) is higher than 17 dB under the mode of velocity measurement, the estimation accuracy of the satellite radial relative velocity is superior to 0.62 m/s..
Laser & Optoelectronics Progress
- Publication Date: Dec. 06, 2016
- Vol. 53, Issue 12, 120603 (2016)
Analysis of Crosstalk in Fiber Grating Sensor Array Caused by Fiber-End Reflection
Zhang Zili, Chen Xiaojun, Ye Bo, and Ge Huiliang
Signal crosstalk of the fiber grating array induced by fiber-end reflection is calculated and analyzed theoretically. The signal crosstalk value of the sensor array element caused by the end reflection is tested by experiment. According to the mechanism of the signal crosstalk, the suppression method of the fiber-end rSignal crosstalk of the fiber grating array induced by fiber-end reflection is calculated and analyzed theoretically. The signal crosstalk value of the sensor array element caused by the end reflection is tested by experiment. According to the mechanism of the signal crosstalk, the suppression method of the fiber-end reflection is proposed, and it is verified by experiment. After suppression of the fiber-end reflection, the crosstalk value is less than -70 dB due to the fiber-end reflection, which can meet the requirement of actual use of the fiber grating sensor array..
Laser & Optoelectronics Progress
- Publication Date: Nov. 23, 2016
- Vol. 53, Issue 12, 120604 (2016)
Fourier Optics and Signal Processing
Joint Fresnel Transform Correlator Based on Phase Encoding
Dou Shuaifeng, Lei Ming, Shen Xueju, and Lin Chao
The joint Fresnel transform correlator is achieved by using a phase-only spatial light modulator to encode linear phase mask. Under the illumination of monochromatic plane wave, the reference image and the target image are modulated by the linear phase mask. In the plane where Fresnel diffraction field centers are supeThe joint Fresnel transform correlator is achieved by using a phase-only spatial light modulator to encode linear phase mask. Under the illumination of monochromatic plane wave, the reference image and the target image are modulated by the linear phase mask. In the plane where Fresnel diffraction field centers are superimposed, the joint Fresnel transform power distribution (JFTPD) of the reference image and the target image can be recorded with a CCD camera. The JFTPD is input to the optical Fourier inverse transform system, and the correlation spots can be obtained in the output plane after Fourier inverse transform. The results of numerical simulations and experiments show that the correlator can output sharp correlation peaks, and the correlation peak values are sensitive to the relative position of the reference image and the target image. When the distance between the reference image and the target image changes by -30 pixel and +40 pixel, the correlation peak value decreases to 23% and 48% respectively..
Laser & Optoelectronics Progress
- Publication Date: Nov. 23, 2016
- Vol. 53, Issue 12, 120701 (2016)
Image Processing
An Improved Texture Image Synthesis Algorithm
Tan Yongqian, Zeng Fanju, Yue Li, and Wu Weiwei
Based on the principle of block splice texture image synthesis, spiral searching path to search matching texture blocks for improving the texture image synthesis speed is studied. In addition, the matching quality is improved, by increasing the number of sample space texture matching blocks. A new texture synthesis algBased on the principle of block splice texture image synthesis, spiral searching path to search matching texture blocks for improving the texture image synthesis speed is studied. In addition, the matching quality is improved, by increasing the number of sample space texture matching blocks. A new texture synthesis algorithm is proposed through a study in sampling space, search methods and similarity of texture block. According to new texture generated by output image, synthesized output images are seen as part of the sample space to enhance the texture blocks probability of matching, by increasing the number of texture matching block in the sample space. The spiral searching manner is used to reduce the search time greatly and improve the synthetic speed. The gradient and color of texture block are taken as the similarity parameters between the two matching blocks, for identifying the similarity degree of two matching blocks. Compared with the traditional algorithms, the proposed algorithm can improve the synthetic speed and synthetic quality with the experimental verification..
Laser & Optoelectronics Progress
- Publication Date: Dec. 06, 2016
- Vol. 53, Issue 12, 121001 (2016)
Imaging Systems
Compressed Imaging Experiments Based on Gradient Projection Algorithm Reconstruction and Image Quality Assessment
Wang Lei, Ma Yanpeng, Yao Bo, Wang Yikun, Han Guicheng, and Qi Hongxing
Compressed imaging avoids pursuing large array devices in infrared band, and it can solve problems like the heterogeneity which is difficult to eliminate during the image acquisition, low sound to noise ratio, higher and higher cost of acquiring, transmitting and storing images in the aerospace imaging applications andCompressed imaging avoids pursuing large array devices in infrared band, and it can solve problems like the heterogeneity which is difficult to eliminate during the image acquisition, low sound to noise ratio, higher and higher cost of acquiring, transmitting and storing images in the aerospace imaging applications and so on. The principle model of the compressed imaging system is analyzed in details, an imaging principle prototype is built, and the experiments of image reconstruction are conducted by the gradient projection algorithm. The signal subspace analysis is introduced in quality assessment of the reconstructed image to estimate the signal to noise ratio of the reconstructed image. Experimental results show that the proposed estimation method is more accurate and effective..
Laser & Optoelectronics Progress
- Publication Date: Dec. 06, 2016
- Vol. 53, Issue 12, 121101 (2016)
Instrumentation, Measurement and Metrology
Identification and Deviation Compensation Research for Grating Signals Based on Genetic Algorithm
Yang Huahui, Feng Weili, and Liu Fu
In order to eliminate the subdivision error of moiré fringe signals in the circular grating measurement process, a parameter identification and deviation compensation method for grating sampled signal is proposed. The method is based on the parameter identification theory of the genetic algorithm and cannot be affIn order to eliminate the subdivision error of moiré fringe signals in the circular grating measurement process, a parameter identification and deviation compensation method for grating sampled signal is proposed. The method is based on the parameter identification theory of the genetic algorithm and cannot be affected by initial signal model parameters with characteristics of optimization and applicability. The regenerated signal model can fit the original signal well. The periodic signals between two grating pitches are sampled with grating rotating at a constant speed in sampling experiments. From the sampled discrete data, the frequency spectra are obtained and analyzed for establishing the mathematical model of grating signals. The parameters which cause the subdivision error are identified by using the genetic algorithm to compensate the subdivision error. The experimental results show that the parameters of signal model constructed by genetic algorithm are identified accurately. The sine deviation of moiré fringe signals is compensated by comparing the Lissajous figures with and without compensation. The subdivision error detected in one grating pitch decreases from 10.65″ to 3.31″. This method can actually be used in grating encoder system and other displacement measuring systems, which ensures the measurement accuracy and reliability..
Laser & Optoelectronics Progress
- Publication Date: Nov. 30, 2016
- Vol. 53, Issue 12, 121201 (2016)
Improved Path-Independent Phase Unwrapping Algorithm Based on Total-Variation Minimum Denoising
Zhang Huiqin, Guo Renhui, Jiang Chao, Zhu Wenhua, and Zhou Xiang
The phase unwrapping algorithms are divided into the path-dependent type and the path-independent type, and can be widely used in the field of optical measurements. An improved path-independent phase unwrapping algorithm based on total-variation minimum denoising is proposed to wipe off the remained noise in the residuThe phase unwrapping algorithms are divided into the path-dependent type and the path-independent type, and can be widely used in the field of optical measurements. An improved path-independent phase unwrapping algorithm based on total-variation minimum denoising is proposed to wipe off the remained noise in the residual phase. Firstly, the phase gradient is determined from the wrapped phase map and subsequently denoised by the total-variation minimization based method. Thus, an approximate phase unwrapped map can be obtained by integrating the denoised phase gradient, and the residual phase map is denoised. The final phase unwrapped map is subsequently determined by adding the first few modes of the unwrapped phase. Error values of unwrapped phase before and after denoising are compared with the original phase by simulations and experiments. The results show that the values of peak-valley and root-mean-square of unwrapped phase with residual phase denoised are lower than those of unwrapped phase with residual phase not denoised..
Laser & Optoelectronics Progress
- Publication Date: Nov. 23, 2016
- Vol. 53, Issue 12, 121202 (2016)
Method of Hybrid Compensation Detection-off-Axis Parabolic Mirror
Zhang Xianzhong, and Yan Gongjing
To accomplish the high-precision testing of aspherical mirror with large aperture and deviation, a hybrid compensation detection model combining subaperture stitching with compensator is proposed. The model can realize high resolution detection of the detected mirror and provide guidance for subsequent processing when To accomplish the high-precision testing of aspherical mirror with large aperture and deviation, a hybrid compensation detection model combining subaperture stitching with compensator is proposed. The model can realize high resolution detection of the detected mirror and provide guidance for subsequent processing when the accuracy of the mirror is not high enough to be achieved by the dynamic range of the interferometer. At the same time, it′s beyond the testing accuracy of the profile measurement. To evaluate the validity of the proposed model, a 1450 mm off-axis parabolic mirror with the hybrid compensation method is tested. To evaluate the testing accuracy, the testing result with the subaperture testing result is compared. The peak and valley value and root mean square value of the residual between them is 0.030λ and 0.003λ respectively, verifying the accuracy and validity of the model..
Laser & Optoelectronics Progress
- Publication Date: Nov. 15, 2016
- Vol. 53, Issue 12, 121203 (2016)
Lasers and Laser Optics
Influence of Supercontinuum Laser on Bioluminescence Imaging Technology
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
For the problem of weak exciting ability and short source life of xenon lamp in fluorescence imaging system, we proposed a new fluorescence excitation method that uses supercontinuum laser (SCL) to be the excitation source in bioluminescence imaging technology. The fluorescence imaging experiments of the fluorescence iFor the problem of weak exciting ability and short source life of xenon lamp in fluorescence imaging system, we proposed a new fluorescence excitation method that uses supercontinuum laser (SCL) to be the excitation source in bioluminescence imaging technology. The fluorescence imaging experiments of the fluorescence imaging test card by the two excitation sources were carried out and then the experiments at different SCL excitation power spectrum density were also completed. By the method of linear fitting and extrapolation, we analyzed the fluorescence excitation ability of the two sources at the same exposure time and power spectrum density. We obtain a conclusion that the fluorescence excitation intensity of SCL source is nearly twice of that of xenon lamp. Finally, through the analysis of the average and maximum photon density of the test perssad under two sources, the experiment results are proved again. The work is conducive to solve the problem of the source life and the fluorescence excitation ability of the light source in fluorescence imaging system..
Laser & Optoelectronics Progress
- Publication Date: Nov. 22, 2016
- Vol. 53, Issue 12, 121401 (2016)
Error Characteristics of Laser Beam Quality Based on Knife-Edge Measuring Method
Liu Haiqiang, Li Wenjuan, Chang Kun, Gao Yang, Ruan Rongbin, and Zhang Zhizhong
In the usage of the knife-edge method, the influences of the measurement errors in the position and the light spot width on the measurement errors in the beam quality factor M2, the far field divergence angle, the beam waist radius, and the light waist position are theoretically investigated. In addition, based on the In the usage of the knife-edge method, the influences of the measurement errors in the position and the light spot width on the measurement errors in the beam quality factor M2, the far field divergence angle, the beam waist radius, and the light waist position are theoretically investigated. In addition, based on the beam quality analysis instrument, the theoretical results are tested. The results show that the influence of the measurement error in the light spot width on the laser beam quality is much stronger than that in the longitudinal position..
Laser & Optoelectronics Progress
- Publication Date: Dec. 06, 2016
- Vol. 53, Issue 12, 121402 (2016)
Interaction Between Excimer Laser and SiC Ceramic
[in Chinese]
Irradiation experiments are conducted on the SiC ceramic using excimer lasers with different pulse number, single-pulse energy, and repetition frequency. The two-dimensional and three-dimensional damage morphologies of irradiation-damaged SiC ceramic are acquired, and the microscopic damage mechanism is analyzed. The rIrradiation experiments are conducted on the SiC ceramic using excimer lasers with different pulse number, single-pulse energy, and repetition frequency. The two-dimensional and three-dimensional damage morphologies of irradiation-damaged SiC ceramic are acquired, and the microscopic damage mechanism is analyzed. The results indicate that, with 193 nm excimer laser irradiating on SiC ceramic, both the photo-thermal and photo-chemical effects are involved and the photo-thermal effect is dominant. The macroscopic damage morphology is closely related to laser irradiation parameters and the increment of either the irradiation pulse number or single-pulse energy aggravates the irradiation damage. Increasing the laser repetition frequency results in a little reduction of scratch depth..
Laser & Optoelectronics Progress
- Publication Date: Dec. 06, 2016
- Vol. 53, Issue 12, 121403 (2016)
Effect of Impulse Coupling Coefficient on Impulse Vector of Laser Irradiating Space Debris
Wang Chenglin, Zhang Yan, and Wang Kunpeng
In order to precisely examine the feature of impulse vector driven by high-energy pulsed laser irradiating space debris, on the basis of assuming linear variations of ablation threshold coefficient, incident laser fluence, and impulse coupling coefficient with the on-target laser fluence, a treatment scheme is proposedIn order to precisely examine the feature of impulse vector driven by high-energy pulsed laser irradiating space debris, on the basis of assuming linear variations of ablation threshold coefficient, incident laser fluence, and impulse coupling coefficient with the on-target laser fluence, a treatment scheme is proposed to elaborately describe the impulse coupling coefficient, and the numerical calculation method of impulse vector is further improved. By taking cylinder debris as an example and referring to simulation experiment, the effect of impulse coupling coefficient on impulse vector is analyzed from different perspectives, and it is pointed out that moderately increasing the incident laser fluence can significantly increase the impulse vector..
Laser & Optoelectronics Progress
- Publication Date: Nov. 25, 2016
- Vol. 53, Issue 12, 121404 (2016)
Effect of Defocusing Amount on Weld Shaping in Fiber Laser Welding of Aluminum Alloy
Zhang Jian, Lin Shijun, Su Shaoxing, Yu Yanling, Fei Wang, Chen Qibao, Cao Yu, and Tang Xiahui
The high power fiber laser is used to conduct a welding experiment on 3 mm thick aluminum alloy, and the effects of the defocusing amount on the morphology, penetration depth, penetration width, root humps, aspect ratios, and width ratio coefficient of weld pools are systematically investigated. The results show that, The high power fiber laser is used to conduct a welding experiment on 3 mm thick aluminum alloy, and the effects of the defocusing amount on the morphology, penetration depth, penetration width, root humps, aspect ratios, and width ratio coefficient of weld pools are systematically investigated. The results show that, with the increase of the defocusing amount, the welding mode is transformed from the deep-penetration welding to heat-conduction one, the weld width does not change obviously, the root hump height and the width ratio coefficient decrease; with the high power fiber laser, the degree of welding bead subsidence and the height of root humps can be reduced by cutting back the negative defocusing amount or transforming into positive defocus; with the low power fiber laser, the back weld width could be increased by strengthening the negative defocusing amount or reducing the positive defocusing amount..
Laser & Optoelectronics Progress
- Publication Date: Dec. 06, 2016
- Vol. 53, Issue 12, 121405 (2016)
Time Delay Signature Concealment in Chaotic Semiconductor Lasers with Double Optical Feedback and Dual-Path Injection
Sun Weiyang, Zhang Shenghai, Wu Tian′an, and Zhang Xiaoxu
It is proposed that a slave semiconductor laser (SL) with dual-path injection (DPI) can be driven by a master SL with double optical feedback (DOF) to conceal the time delay signature from both intensity and phase chaos. With the usage of auto-correlation function (ACF) and mutual information (MI) function, the time deIt is proposed that a slave semiconductor laser (SL) with dual-path injection (DPI) can be driven by a master SL with double optical feedback (DOF) to conceal the time delay signature from both intensity and phase chaos. With the usage of auto-correlation function (ACF) and mutual information (MI) function, the time delay signature concealment effects under different schemes are compared and analyzed. The research results indicate that, as for the same type of lasers with the same parameter ranges, the time delay signature can be better concealed with the DOF-DPI scheme than the other schemes. In addition, as for the scheme with chaotic light injection, the concealing effect of the phase time delay characteristic is better than that of the intensity time delay characteristic; on the same concealment level of time delay characteristic peaks, the DOF-DPI scheme has a wider parameter range than the other schemes..
Laser & Optoelectronics Progress
- Publication Date: Dec. 06, 2016
- Vol. 53, Issue 12, 121406 (2016)
Machine Vision
Saliency Detection Optimization Method in Natural Scene
Mou Li, Zhang Xuewu, Zhang Zhuo, Li Min, and Fan Xinnan
A new saliency detection optimization method is proposed to satisfy the accuracy requirement of saliency detection in the natural scene. The method can divide an image into multiple superpixel areas using the simple linear iterative clustering algorithm, and extract the contrast feature of color regions. The general taA new saliency detection optimization method is proposed to satisfy the accuracy requirement of saliency detection in the natural scene. The method can divide an image into multiple superpixel areas using the simple linear iterative clustering algorithm, and extract the contrast feature of color regions. The general target geometric center is located by the Harris corner detection algorithm. The center probability is used to describe the target space distribution feature, and the adaptive feature fusion for the target location is carried out. Optimization of a saliency map with background suppression and target enhancement is realized based on target space distribution feature and image gray centroid. The continuity of the saliency map can be enhanced by the space smoothing technique for the saliency value. Experimental results show that the test with this method does not only have high precision rate and recall rate, but also has low mean absolute error in several testing sets, and the method can be applied to the saliency detection in complex natural scenes..
Laser & Optoelectronics Progress
- Publication Date: Nov. 18, 2016
- Vol. 53, Issue 12, 121501 (2016)
Adaptive Object Tracking Based on Hierarchical Convolution Features
Mao Ning, Yang Dedong, Yang Fucai, and Cai Yuzhu
An adaptive object tracking algorithm based on hierarchical convolution features is proposed to solve the problems of variable scale, rotation and occlusion in object tracking. The hierarchical convolution features are extracted using the convolution neural network, the response maps of convolution features are obtaineAn adaptive object tracking algorithm based on hierarchical convolution features is proposed to solve the problems of variable scale, rotation and occlusion in object tracking. The hierarchical convolution features are extracted using the convolution neural network, the response maps of convolution features are obtained by the correlation filtering algorithm, and the weighted fusion response is employed to estimate the location of object. An edge detection algorithm is used to realize the scale adaptive tracking. Peak-side-ratio is used to judge the object confidence and solve the problem of template updating under occlusion. The proposed algorithm is tested in the OTB2013 database. The overall success rate and the precision of the proposed algorithm is 0.618 and 0.861, respectively. In the case of object scale variation, rotation and occlusion, the proposed algorithm can accurately and reliably track the object..
Laser & Optoelectronics Progress
- Publication Date: Nov. 26, 2016
- Vol. 53, Issue 12, 121502 (2016)
Materials
Design and Study of Double Parallel Junctions Solar Cells
Huang Qianlu, Zhou Haifeng, Qian Yiwei, and Wang Qiang
A double parallel junctions (DPJ) silicon solar cell structure is designed. The solar cell forms a PN junction and a NP junction in the same monocrystalline silicon solar cell, respectively, which absorbs short wave energy and long wave energy. The two junctions share a N-type region and form a parallel structure by thA double parallel junctions (DPJ) silicon solar cell structure is designed. The solar cell forms a PN junction and a NP junction in the same monocrystalline silicon solar cell, respectively, which absorbs short wave energy and long wave energy. The two junctions share a N-type region and form a parallel structure by the N-type region. The short circuit current of the solar cells is increased about 11.9% compared with the traditional monocrystalline silicon solar cells, and the open circuit voltage of the solar cells keeps constant. The optimal technological condition of DPJ solar cells is studied, and the results show that the spectrum response of the solar cells enhances firstly, and then decreases with the increasing of diffusion concentration for deep junction and shallow junction. The spectrum response of the solar cells increases firstly, then remains unchanged with the redistribution diffusion temperature raising and the diffusion time extending of the impurities after the diffusion of deep junction is completed. The spectrum response of the solar cells increases slightly with the increase of shallow junction diffusion time and temperature..
Laser & Optoelectronics Progress
- Publication Date: Nov. 20, 2016
- Vol. 53, Issue 12, 121601 (2016)
Optical Design and Fabrication
High Order Aspheric Testing with Large Asphericity, Fast Focal Ratio and Large Diameter
He Li, Wu Zhonghua, Kang Yan, and Su Zhide
In recent years, the optical element with large diameter, large asphericity, fast focal ratio, high-order aspheric has been used in astronomical optics, space optics and space target detection and recognition with ground-based systems and other fields more and more widely. At present we commonly use null lens testing sIn recent years, the optical element with large diameter, large asphericity, fast focal ratio, high-order aspheric has been used in astronomical optics, space optics and space target detection and recognition with ground-based systems and other fields more and more widely. At present we commonly use null lens testing system or partial compensation system with eliminating return error process to test such optical elements. Among them, partial compensation system with eliminating return error process is complex and lack of testing intuitiveness, and the measurement accuracy cannot be guaranteed. Therefore, in the testing of some mirror with very high surface error precision requirement, this method is not applicable. Base on the test of concave high-order aspherical mirror with diameter of 1020 mm, coke ratio of 1/0.5, aspherical degree of 1.8 mm, high-order term of 6, an idea to design zero compensation testing light path by stages is proposed, which can satisfy the requirement of different stages of developing and testing such as rough polishing, fine polishing, interferometer testing. Final, its surface accuracy achieves λ/50..
Laser & Optoelectronics Progress
- Publication Date: Nov. 20, 2016
- Vol. 53, Issue 12, 122201 (2016)
Design of LED Lens with Ultra-High Light Efficiency and Small Light-Gathering Angle for Realizing Uniform Light Distribution
Wan Yunjia, Lin Haobo, Liu Jie, and Xiong Hui
A design for freeform surface lens with ultra-high light efficiency and small light-gathering angle is proposed to realize uniform light distribution for LED light source. A freeform surface differential equation is constructed based on the refraction phenomenon when light is passing through the lens. High accuracy algA design for freeform surface lens with ultra-high light efficiency and small light-gathering angle is proposed to realize uniform light distribution for LED light source. A freeform surface differential equation is constructed based on the refraction phenomenon when light is passing through the lens. High accuracy algorithm is applied to obtaining parameters of the lens surface. The light distribution effect achieved from the proposed method is with smaller light gathering angle and higher light efficiency than those obtained from the traditional lens. A three-dimensional model is established by the professional software. The thickness of the lens can be reduced by cutting a sphere inside the lens model. The simulation in real application environment verifies the validity and the reliability of the scheme..
Laser & Optoelectronics Progress
- Publication Date: Nov. 24, 2016
- Vol. 53, Issue 12, 122202 (2016)
Design of Three-Group Flexible High Ratio Zoom Optical System
Li Hongzhuang
High ratio zoom lens design using three-group flexible structure is researched. The Guassian optics for three-group structure with fixed middle group is discussed. The range of Guassian parameters and principle of selection for high ratio design are presented. The visible assist design software for Guassian parameters High ratio zoom lens design using three-group flexible structure is researched. The Guassian optics for three-group structure with fixed middle group is discussed. The range of Guassian parameters and principle of selection for high ratio design are presented. The visible assist design software for Guassian parameters selection is developed. A flexible zoom lens with ratio 50×, focal length 12~600 mm, and field of view 0.85°~41.2° is designed. The optical total length is 175 mm for short focal length, 309 mm for long focal length, and the telephoto ratio of long focal length is 0.51. The modulation transfer function (MTF) at 100 lp/mm for each focal length is higher than 0.3 at center field, and higher than 0.2 at edge field. The system possesses the characters of miniature and portable..
Laser & Optoelectronics Progress
- Publication Date: Nov. 20, 2016
- Vol. 53, Issue 12, 122203 (2016)
Optical Devices
Structure of Chip Scale Package for LED Light Source and Its Thermal Performance Analysis Based on Numerical Simulation
Liu Chao, Fu Renli, Gu Xiguang, Zhou Ming, Tian Yang, and Cai Junde
In this paper, the thermal performance of chip scale packaged (CSP) LED was studied by numerical simulation and demonstrated by experiments. Heat dissipation characteristics of CSP LED modules which were packaged upon an aluminum substrate with a diameter of 25 mm and a thickness of 1 mm were computed by finite volume In this paper, the thermal performance of chip scale packaged (CSP) LED was studied by numerical simulation and demonstrated by experiments. Heat dissipation characteristics of CSP LED modules which were packaged upon an aluminum substrate with a diameter of 25 mm and a thickness of 1 mm were computed by finite volume method, and the study showed that the chip junction temperature was closely related to chip power and distance between chips. To achieve technical requirement of junction temperature below 120 ℃, the distance and chip power both need considering. When the distance was 3.5 mm, only the single chip power of 0.5 W could meet the requirement. As the distance increased, the chip power could rise gradually. When the distance was 7.25 mm, chips whose power was less than 3 W could be applicable to the packaging. While the total input power was certain, thermal resistance of module decreased with the increased of packing density. When the packing density was 15.13%, module thermal resistance dropped to 2.26 K/W. Chip scale package is development direction of the next generation of LED packaging because of the lower thermal resistance..
Laser & Optoelectronics Progress
- Publication Date: Nov. 30, 2016
- Vol. 53, Issue 12, 122301 (2016)
OPTOELECTRONICS
Improvement and Application of IMM-UKF Algorithm in Two Coordinate Radar-Optoelectronic Fusion Tracking System
Li Ke, Li Xingfei, and Yang Fan
Optoelectronic and radar data fusion can achieve complementary of two single sensors measuring information, and improve target recognition and tracking capability. Aiming at the presence of outliers in localization of combined sensor system to dynamic motion target, meanwhile, in order to solve a single sensor trackingOptoelectronic and radar data fusion can achieve complementary of two single sensors measuring information, and improve target recognition and tracking capability. Aiming at the presence of outliers in localization of combined sensor system to dynamic motion target, meanwhile, in order to solve a single sensor tracking filtering divergence problem, a resist outliers interacting multiple model unscented Kalman filter (IMM-UKF) fusion algorithm is proposed. Under the condition of two coordinate radar providing target range and azimuth angle, parameter solving model is established and the pitch angle of target is obtained. Fusion filter is carried on by combining angle information provided by photoelectric sensor. Experiment and simulation results show that the algorithm can effectively integrate radar and optoelectronic measurement data, eliminate the interference of outliers, suppress filter divergence and improve positioning accuracy..
Laser & Optoelectronics Progress
- Publication Date: Nov. 20, 2016
- Vol. 53, Issue 12, 122501 (2016)
Reviews
Research Progress on Wavefront Aberration Detection Technology of Meter-Sized Optical Elements in Inertial Confinement Fusion Systems
Xu Longbo, Zhou You, Zhu Rihong, and Liu Shijie
The low and medium frequency wavefront aberration detection techniques of meter-sized optical elements applied in inertial confinement fusion system and their research progress are introduced, which includes direct detection based on large-aperture Fizeau interferometers, Ritchey-Common detection method, oblique detectThe low and medium frequency wavefront aberration detection techniques of meter-sized optical elements applied in inertial confinement fusion system and their research progress are introduced, which includes direct detection based on large-aperture Fizeau interferometers, Ritchey-Common detection method, oblique detection method, and sub-aperture stitching detection method. The introduction of measurement errors and corresponding elimination methods are illustrated, and the necessity of further improving the measurement accuracy of wavefront aberration and methods are prospected..
Laser & Optoelectronics Progress
- Publication Date: Dec. 06, 2016
- Vol. 53, Issue 12, 120001 (2016)
Integrated Transmitter and Receiver Chips for Data Center
Li Chaoyi, An Junming, Zhang Jiashun, Wang Liangliang, Wu Yuanda, Yin Xiaojie, and Wang Yue
At present the optical module package types have been changed gradually from small form-factor pluggable (SFP) series to centum form-factor pluggable (CFP) and quad SFP (QSFP) series. Transmission rate is up to 400 Gb/s. Transmitting lasers′extinction ratio (ER) is more than 9 dB. Optical wavelength division multiplexeAt present the optical module package types have been changed gradually from small form-factor pluggable (SFP) series to centum form-factor pluggable (CFP) and quad SFP (QSFP) series. Transmission rate is up to 400 Gb/s. Transmitting lasers′extinction ratio (ER) is more than 9 dB. Optical wavelength division multiplexers′insert loss (IL) is less than 1 dB. Transmitting power is more than 0.3 dBm. Receiving detector′s responsivity is 0.7 A/W and receiving sensitivity is less than -17 dBm. Transmitting and receiving integrated chips in the data center, which can be applied on the 40/100 GbE, standardized as IEEE 802.3 ba, is demonstrated, including the discrete devices assembly chip, hybrid integration chip and monolithic integration chip, whose basic structures and characteristics are introduced as well..
Laser & Optoelectronics Progress
- Publication Date: Dec. 06, 2016
- Vol. 53, Issue 12, 120002 (2016)
Optical Analog-to-Digital Conversion Technology and Its Recent Progress
Zhang Tianhang, Qiu Qi, Su Jun, Yu Zhenfang, and Fan Zhiqiang
In analog-to-digital conversion systems, the optical analog-to-digital conversion (OADC) technology becomes a research hotspot because it can increase the system bandwidth, improve the sampling rate and overcome the bottleneck of electronic systems. The classification of OADC technology is discussed. The fundamental prIn analog-to-digital conversion systems, the optical analog-to-digital conversion (OADC) technology becomes a research hotspot because it can increase the system bandwidth, improve the sampling rate and overcome the bottleneck of electronic systems. The classification of OADC technology is discussed. The fundamental principle, implementation method and technical feature of various OADC technologies are introduced. Key technologies, which include sampling pulse generation, multichannel parallel multiplexing, space interferometry and optical nonlinear effect application, are deeply analyzed based on high-speed optical sampling and optical quantizing. The research progress and technology index of the related technologies are introduced..
Laser & Optoelectronics Progress
- Publication Date: Nov. 18, 2016
- Vol. 53, Issue 12, 120003 (2016)
Research Progress on Photonic Neuromorphic Computing
Wang Rui, Ren Quansheng, and Zhao Jianye
Photonic neuromorphic system can simulate the neuromorphic algorithms with a speed of millions or billions multiples faster than the biological counterpart, which is better than electronics neuromorphic hardware system. It can be also capable of processing computing tasks more sophisticated than traditional optical comPhotonic neuromorphic system can simulate the neuromorphic algorithms with a speed of millions or billions multiples faster than the biological counterpart, which is better than electronics neuromorphic hardware system. It can be also capable of processing computing tasks more sophisticated than traditional optical computations. The photonic neuromorphic computing, exploring the adaptability, robustness and rapidity of ultrafast optical pulses, can overcome the scaling of digital optical computation and the noise accumulation of analog optical computation. The research progress on photonic neuromorphic computing is reported. Some essential theories and technologies, including photonic neuron, learning algorithms based on optical spiking pulses and the integrated photonic neuromorphic network framework, are introduced respectively. The necessity of research on photonic neuromorphic computing and its problems are discussed to present its potential applications in future..
Laser & Optoelectronics Progress
- Publication Date: Nov. 20, 2016
- Vol. 53, Issue 12, 120004 (2016)
Spectroscopy
Moisture Content Detection of Maize Kernels Based on Hyperspectral Imaging Technology and CARS
Wang Chaopeng, Huang Wenqian, Fan Shuxiang, Zhang Baohua, Liu Chen, Wang Xiaobin, and Chen Liping
In order to realize accurate, rapid and nondestructive detection for moisture content (MC) of maize kernel and avoid effects of placement state (embryo up or down) on detection results, a novel detection method based on hyperspectral imaging and image processing techniques is proposed. The variable selection method is In order to realize accurate, rapid and nondestructive detection for moisture content (MC) of maize kernel and avoid effects of placement state (embryo up or down) on detection results, a novel detection method based on hyperspectral imaging and image processing techniques is proposed. The variable selection method is used to establish MC prediction model according to the placement state of maize kernel. The hyperspectral images including both front and reverse side of maize kernel are acquired, spectral data in centroid region is extracted, and competitive adaptive reweighted sampling algorithm is used for characteristic wavelength selection. And the prediction models including front and reverse side prediction model are built for MC prediction. The spectral curves in different parts of hyperspectral images are contrasted mutually to judge if the maize kernel appeared in the image is front side upward (embryo up) or not, and four wavebands (1104, 1304, 1454, 1751 nm) are selected for front and reverse side detection with band math. The MC of 45 validation set samples are detected with the proposed algorithm. Results show that the accuracy of front and reverse side detection is about 97.8%, 100%, respectively, the validation set correlation coefficient of front and reverse side are 0.969, 0.946, respectively, the root mean square error are 0.464%, 0.616%, respectively. This research establishes foundation for the MC detection of maize kernel with multi-spectral technique..
Laser & Optoelectronics Progress
- Publication Date: Nov. 17, 2016
- Vol. 53, Issue 12, 123001 (2016)
Determination of Vintages of Sesame Flavor Liquors by Three-Dimensional Fluorescence Spectroscopy
Xi Liuhua, Chen Guoqing, Zhu Zhuowei, Wu Yamin, Ma Chaoqun, Zhao Jinchen, Du Jiameng, Gu Song, and Zhang Xiaohe
In order to determine the vintages of the sesame flavor liquors, the three-dimensional fluorescence spectra of 11 aged liquor samples brewed from 1984 to 2012 are measured with an FLS920 multifunctional fluorescence spectrometer. Average fluorescence intensity, standard deviation of numerical matrix and maximal relativIn order to determine the vintages of the sesame flavor liquors, the three-dimensional fluorescence spectra of 11 aged liquor samples brewed from 1984 to 2012 are measured with an FLS920 multifunctional fluorescence spectrometer. Average fluorescence intensity, standard deviation of numerical matrix and maximal relative fluorescence intensity of the three-dimensional fluorescence spectra are extracted for polynomial fitting. Two prediction models for the vintages of aged liquors are established with partial least squares regression calibration and quadratic optimal regression calibration combined, respectively. The vintages of aged liquors of 1989, 1994, 1996, 2002, 2003, 2005, 2006, 2009, 2011 are predicted by the two models above, and the average absolute errors are 0.68 and 0.56, respectively. The results show that the established models can effectively determine the vintages of aged liquors. The nonlinear calibration model has better precision than the linear calibration model. The aged liquors are studied by three-dimensional fluorescence spectra combined with regression-calibrated polynomial functions, which paves a way for the determination of vintages of aged liquors..
Laser & Optoelectronics Progress
- Publication Date: Nov. 30, 2016
- Vol. 53, Issue 12, 123002 (2016)
Thin Films
Characteristics of Compactness of SiO2 Thin Films Prepared by PECVD Method
Xiao Heping, Sun Rujian, Ma Xiangzhu, Yang Kai, and Zhang Shuangxiang
Plasma enhanced chemical vapor deposition (PECVD) method is applied to prepare SiO2 thin films, and the compactness is characterized by refractive index. The relationship between SiO2 thin film compactness and radio-frequency (RF) power, substrate temperature, chamber pressure, N2O/SiH4 flow rate is studied. RefractivePlasma enhanced chemical vapor deposition (PECVD) method is applied to prepare SiO2 thin films, and the compactness is characterized by refractive index. The relationship between SiO2 thin film compactness and radio-frequency (RF) power, substrate temperature, chamber pressure, N2O/SiH4 flow rate is studied. Refractive index is measured by Filmetrics thin film thickness gauge F20 and surface microstructure is measured by focus ion beam scanning electron microscopes (FIB-SEM). Energy dispersive X-ray (EDX) is used to analyze the influence of Si, O and N element contents in thin films on the compactness with different process parameters. Design of experiments (DOE) of multi-factors is carried out. The optimum refractive index and structure growth condition under various conditions are got. The mechanism of compactness of SiO2 thin film changing with process conditions is studied..
Laser & Optoelectronics Progress
- Publication Date: Nov. 20, 2016
- Vol. 53, Issue 12, 123101 (2016)
Comparison of Hastelloy Coating and Fe-Based Amorphous Composite Coating Prepared by Laser Cladding on Q235 Steel
Wang Qinying, Pu Yuwei, Liu Shuang, Xi Yuchen, and Bai Shulin
Hastelloy coating and Fe-based amorphous composite coating were prepared by pulsed laser on Q235 steel substrate. Scanning electron microscope, X-ray diffractionmeter, Vickers hardness tester and electrochemical system were applied to characterizing the microstructure, phase composition, hardness and corrosion resistanHastelloy coating and Fe-based amorphous composite coating were prepared by pulsed laser on Q235 steel substrate. Scanning electron microscope, X-ray diffractionmeter, Vickers hardness tester and electrochemical system were applied to characterizing the microstructure, phase composition, hardness and corrosion resistance of coatings. The results show that metallurgical bonding interface without obvious cracks and pores is observed between both coatings and substrate. Furthermore, Fe-based amorphous composite coating displays both crystalline structure and amorphous structure, while Hastelloy coating mainly owns eutectic and primary structures. It is found that two types of coatings show the similar corrosion resistance, while the Fe-based amorphous composite coating exhibits higher hardness than the Hastelloy coating..
Laser & Optoelectronics Progress
- Publication Date: Nov. 19, 2016
- Vol. 53, Issue 12, 123102 (2016)
Ultrafast Optics
Experiment Study on Carrier-Envelope Offset Frequency Locking in a Femtosecond Fiber Comb
Xia Chuanqing, Wu Tengfei, Zhao Chunbo, Han Jibo, Li Shuyi, Xing Shuai, and Zhang Lei
A home-made fiber comb is developed based on the technology of Erbium-doped fiber femtosecond laser. The system configuration, working process and performance parameters of this comb are described in detail. A supercontinuum more than one octave is obtained after power amplification, dispersion optimization and spectruA home-made fiber comb is developed based on the technology of Erbium-doped fiber femtosecond laser. The system configuration, working process and performance parameters of this comb are described in detail. A supercontinuum more than one octave is obtained after power amplification, dispersion optimization and spectrum spreading in highly nonlinear fibers. The carrier-envelope offset frequency (fo) is extracted by means of a linear f-2f interferometer and locked to a Rubidium atomic clock. The observed signal-to-noise ratio of fo is 35 dB and steady operation with locking time more than 12 h is demonstrated..
Laser & Optoelectronics Progress
- Publication Date: Dec. 06, 2016
- Vol. 53, Issue 12, 123201 (2016)
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