检索结果-内蒙古大学图书馆

Numerical and experimental study on coherent beam combining using an improved stochastic parallel gradient descent algorithm

引用

LASER PHYSICS 2020年第8期30卷

作者： Song, Jikun Li, Yuanyang Che, Dongbo Wang, Tingfeng Chinese Acad Sci Changchun Inst Opt Fine Mech & Phys State Key Lab Laser Interact Matter Changchun 130033 Peoples R China Univ Chinese Acad Sci Ctr Mat Sci & Optoelect Engn Beijing 100049 Peoples R China

The adaptive gradient (AdaGrad) method is an optimization algorithm widely used in the field of artificial intelligence. An adaptive gradient stochastic parallel gradient descent (SPGD) algorithm (AdaSPGD algorithm), combining an AdaGrad algorithm with an SPGD algorithm, is innovatively introduced and implemented in coherent beam synthesis. The performance of a coherent beam combination system utilizing the AdaSPGD method is validated by numerical simulation of straightening static phase aberrations. The results of the simulations indicate that the AdaSPGD algorithm not only can effectively solve the trouble of difficulty in selecting the gain coefficient in the actual beam combining system, but also can accelerate the convergence of the phase control algorithm. Furthermore, the effectiveness of the proposed algorithm is demonstrated by means of the experimental investigation on coherent beam synthesis of a two-channel fiber array. The AdaSPGD algorithm is a satisfactory modification of the conventional SPGD algorithm.

关键词： coherent beam combining adaptive gradient stochastic parallel gradient descent algorithm

来源：评论

学校读者我要写书评

暂无评论

Laser beam shaping based on wavefront sensorless adaptive optics with stochastic parallel gradient descent algorithm 14

Laser beam shaping based on wavefront sensorless adaptive op...

引用

14th National Conference on Laser Technology and Optoelectronics (LTO)

作者： Li, Yan Peng, Tairan Li, Wenlai Han, Hongming Ma, Jianqiang Ningbo Univ Fac Mech Engn & Mech Ningbo 315211 Zhejiang Peoples R China

ISBN: (数字)9781510630475

ISBN: (纸本)9781510630475

A wavefront sensorless adaptive optics system with a 61-element unimorph deformable mirror is proposed for laser beam shaping. The actuator voltages of the DM are adaptively adjusted with the help of the stochastic parallel gradient descent (SPGD) algorithm. The difference of the target beam and the actual beam recorded by a CCD camera is used as feedback. The experimental results show that this method not only realizes the aberrations correction of the optical system, but also generates annular beam, ratio line focus beam and square beam which agree with the desired targets.

关键词： beam shaping adaptive optics deformable mirror stochastic parallel gradient descent algorithm

来源：评论

学校读者我要写书评

暂无评论

Performance investigation of stochastic parallel gradient descent algorithm based wave-front sensor-less adaptive optics for atmosphere turbulence compensation 4

Performance investigation of stochastic parallel gradient de...

引用

4th Seminar on Novel Optoelectronic Detection Technology and Application

作者： Yu, Zhihao Li, Yan Li, Beibei Zheng, Donghao Li, Wei Qiu, Jifang Zuo, Yong Hong, Xiaobin Guo, Hongxiang Wu, Jian Beijing Univ Posts & Telecommun State Key Lab Informat Photon & Opt Commun Beijing 100876 Peoples R China

ISBN: (数字)9781510619487

ISBN: (纸本)9781510619487

stochastic parallel gradient descent (SPGD) algorithm is a kind of simple and practicable algorithm for adaptive optics (AO) to compensate the effects of turbulence. The relationship between the number of control variables and convergence effects is explored experimentally in this paper. We find that the number of control variables is not always the larger the better. Under the condition of weak turbulence, the algorithm with 6x6 control variables gives better results than 12x12 control variables and 8x8 control variables. With the increase of turbulence strength, the convergence effects of 12x12 control variables are better than 6x6 control variables and 8x8 control variables. In the condition of weak turbulence, SPGD algorithm with 6x6, 8x8, 12x12 control variables can improve coupling efficiency by 3.2dB, 3.1dB and 3.0dB respectively. In the condition of moderate turbulence, SPGD algorithm with 6x6, 8x8, 12x12 control variables can improve coupling efficiency by 6.4dB, 6.6dB, 7.1dB respectively. In the condition of strong turbulence, SPGD algorithm with 6x6, 8x8, 12x12 control variables can improve coupling efficiency by 6.2dB, 7.1dB, 10.2dB respectively.

关键词： free space optics communication adaptive optics stochastic parallel gradient descent algorithm

来源：评论

学校读者我要写书评

暂无评论

Generation of needle-shaped beam with super-resolution spot and large depth of focus using diffractive optics

引用

OPTICS COMMUNICATIONS 2024年 563卷

作者： Du, Yuzhe Zhang, Cilong Tan, Qiaofeng Tsinghua Univ Dept Precis Instrument State Key Lab Precis Measurement Technol & Instrum Beijing 100084 Peoples R China

The finite depth of focus (DOF) of a focusing lens gives rise to the degradation of lateral resolution at defocused positions. Consequently, the generation of a needle -shaped beam with sub -diffraction size and extended DOF can break through this limitation, but few studies have effectively balanced these two characteristics. In this paper, we propose a method based on the stochastic parallel gradient descent (SPGD) algorithm for designing multi -ring diffractive optical elements (DOEs) to produce the needle -shaped beam, which maintains a super -resolution and uniform spot within a large extended DOF range. Numerical simulations and experimental results have validated that our method can extend the DOF by 14 times longitudinally and reduce the lateral resolution to 73% of Airy spot, while maintaining up to 92% uniformity of the beam diameter. Furthermore, we demonstrate that the DOF of the needle -shaped beam extends with the increase of the number of rings and phase levels within the DOE. Our work provides an effective strategy for the design of DOF-extended DOE and it is anticipated to find potential applications in microscopy and three-dimensional imaging, photolithography, and optical manipulation.

关键词： Needle -shaped beam Diffractive optical elements stochastic parallel gradient descent algorithm Super -resolution spot Extended depth of focus

来源：评论

学校读者我要写书评

暂无评论

Experimental study on correction of non-common path aberrations in free-space coherent optical communication

引用

INDIAN JOURNAL OF PHYSICS 2023年第5期97卷 1581-1590页

作者： Ke, X. Wu, J. Wang, Y. Xian Univ Technol Fac Automat & Informat Engn Xian 710048 Peoples R China Shaanxi Univ Technol Fac Phys & Telecommun Engn Hanzhong 723003 Peoples R China Shaanxi Civil Mil Integrat Key Lab Intelligence C Xian 710126 Peoples R China

Adaptive optics (AO) technology is based on the principle of real-time measurement and compensation to correct beam wavefront distortion. In a practical communication system, the correction and communication optical paths are separated and independent. Thus, non-common optical path aberrations occur in beam wavefront corrections. In this study, the relationship between non-common path aberrations and wavefront of the system is established, and the stochastic parallel gradient descent algorithm is proposed to correct non-common path aberrations. In the experiment, the influence of the non-common path aberrations on the optical power value is analyzed by considering the optical power value coupled into the single-mode fiber (SMF) as the evaluation index. When the non-common path aberrations are corrected, the power value coupled into the SMF is improved from - 44.2, - 41.54, and - 43.72 to - 33.41, - 30.03, and - 34.6 dBm, respectively. The wavefront distortion correction based on the dual fuzzy proportional integral differential algorithm is also investigated. The results show that, after the correction, the wavefront peak-to-valley and root-mean-square values are significantly reduced under different weather conditions and the system intermediate frequency voltage is worth improving.

关键词： Coherent optical communication Non-common path aberrations stochastic parallel gradient descent algorithm Dual fuzzy proportional integral differential algorithm

来源：评论

学校读者我要写书评

暂无评论

Continuous Tracking and Pointing of Coherent Beam Combining System via Target-in-the-Loop Concept

引用

IEEE PHOTONICS TECHNOLOGY LETTERS 2021年第20期33卷 1119-1122页

作者： Yang, Xu Huang, Guan Li, Feng Li, Xiaoyang Li, Bincheng Geng, Chao Li, Xinyang Chinese Acad Sci Key Lab Adapt Opt Chengdu 610209 Peoples R China Univ Elect Sci & Technol China Sch Optoelect Sci & Engn Chengdu 610054 Peoples R China Chinese Acad Sci Inst Opt & Elect Chengdu 610209 Peoples R China Northwestern Polytech Univ Sch Elect & Informat Xian 710129 Peoples R China

We demonstrate a technique to realize fine target tracking and pointing using target-in-the-loop (TIL) concept via a coherent beam combining (CBC) system. A tracking and pointing system is composed of a densely packed array of 7 phase-control elements with simultaneous piston and tilt controls of the outgoing beams wavefront phases. A photo-detector (PD) with a pinhole is used as target detection and installed on a translation stage. Energy detected by the mobile PD is used for evaluating the beam combining and scanning performance, and to provide the feedback signal for controls of piston and tilt phases of the transmitted beams by using the stochastic parallel gradient descent (SPGD) algorithm for merit function maximization.

关键词： Laser beams Phased arrays Pistons Optical arrays Optical transmitters Lenses Target tracking Beam combining beam scanning tracking and pointing piston control tilt control stochastic parallel gradient descent algorithm

来源：评论

学校读者我要写书评

暂无评论

SPGD and Newton iteration mixed algorithm used in freeform surface metrology

引用

OPTICS AND LASERS IN ENGINEERING 2020年 129卷 106050-106050页

作者： Zhang, Yu Tian, Xiaobo Liang, Rongguang Northeast Elect Power Univ Coll Sci Inst Mat Phys Jilin 132012 Jilin Peoples R China Chinese Acad Sci Changchun Inst Opt Fine Mech & Phys State Key Lab Appl Opt Changchun 130022 Jilin Peoples R China Univ Arizona Coll Opt Sci Tucson AZ 85721 USA

Freeform surfaces are widely used in advanced optical systems. In order to accurately measure freeform surfaces, an adaptive interferometer with deformable mirror (DM) has been developed for the freeform surface metrology. To ensure the efficiency, a stochastic parallel gradient descent (SPGD) and Newton iteration mixed algorithm to drive the DM has been proposed, it can achieve the minimum value of the optimization and is suitable for the different interferograms. The simulation and experimental results verify the correctness and feasibility of the proposed DM driving algorithm.

关键词： stochastic parallel gradient descent algorithm Newton iteration algorithm Deformable mirror Freeform surface Optimization

来源：评论

学校读者我要写书评

暂无评论

An algorithm combining convolutional neural networks with SPGD for SLAO in FSOC

引用

OPTICS COMMUNICATIONS 2020年 475卷 126243-126243页

作者： Gu, Haijun Liu, Meiqi Liu, Haoyu Yang, Xue Liu, Wei Jilin Univ Coll Commun Engn 5372 Nanhu Rd Changchun 130012 Peoples R China

The wavefront distortion in the free space optical communication (FSOC) can be mitigated with sensor-less adaptive optics (SLAO). The SLAO controlling algorithm plays an important role for system performance, but the conventional methods still cannot reach satisfaction. This paper presents a hybrid method to improve the calibration efficiency and accuracy, in which convolutional neural networks (CNN) model coarsely classifies and corrects the aberrations, and then stochastic parallel gradient descent (SPGD) algorithm finely corrects aberrations. Simulations show that it can improve the speed for the distortion compensation and avoid the problem falling into local optimum in traditional SPGD. This hybrid method can improve coupling efficiency of the optical carrier in the SLAO and enable FSOC to achieve a higher Strehl ratio (SR) under atmospheric turbulence.

关键词： Sensor-less adaptive optics stochastic parallel gradient descent algorithm Convolutional neural networks

来源：评论

学校读者我要写书评

暂无评论

Indirectly coherent beam combining of pulsed lasers based on active control of continuous carrier

引用

OPTICAL ENGINEERING 2021年第6期60卷 066111-066111页

作者： Zou, Fan Zuo, Jing Geng, Chao Li, Feng Jiang, Jiali Liu, Jiaying Zhou, Xin Fan, Zhihua Ma, Xiaoyu Li, Xinyang Chinese Acad Sci Key Lab Adapt Opt Chengdu Peoples R China Chinese Acad Sci Inst Opt & Elect Chengdu Peoples R China Univ Chinese Acad Sci Beijing Peoples R China Sichuan Univ Arts & Sci Dazhou Peoples R China

High-power and high-quality pulsed fiber lasers with low repetition frequency are widely applied to various fields ranging from basic science to industrial applications. Coherent beam combining (CBC) is a significant method to obtain that beam, but few methods used for large-scale CBC of pulsed fiber lasers with low repetition frequency were presented. To realize it, a new method based on a continuous carrier was designed, where the continuous wave worked as the beacon signal, and the stochastic parallel gradient descent algorithm was employed for phase locking and tilt correction. The beam combining experiment revealed that the combining efficiency of two lasers with a repetition frequency of 15 kHz and a pulse width of 100 ns was 95%, and the fringe contrast in the center of the far-field spot was improved about three times. This method promises to be furtherly applied to combine the pulsed lasers with lower repetition frequency and narrower pulse width. These results pave the way for large-scale CBC of high-power and high-quality pulsed fiber lasers. (C) 2021 Society of Photo-Optical Instrumentation Engineers (SPIE)

关键词： pulsed laser coherent combining continuous carrier tilt correction stochastic parallel gradient descent algorithm

来源：评论

学校读者我要写书评

暂无评论

7.1 kW coherent beam combining system based on a seven-channel fiber amplifier array

引用

OPTICS AND LASER TECHNOLOGY 2021年 140卷 107016-107016页

作者： Ma, Pengfei Chang, Hongxiang Ma, Yanxing Su, Rongtao Qi, Yunfeng Wu, Jian Li, Can Long, Jinhu Lai, Wenchang Chang, Qi Hou, Tianyue Zhou, Pu Zhou, Jun Natl Univ Def Technol Coll Adv Interdisciplinary Studies Changsha 410073 Peoples R China Chinese Acad Sci Shanghai Inst Opt & Fine Mech Shanghai Key Lab All Solid State Laser & Appl Tec Shanghai 201800 Peoples R China

Coherently combining of seven-channel narrow-linewidth, linear-polarized, kW-level power all-fiber amplifiers has been successfully demonstrated by using the stochastic parallel gradient descent (SPGD) algorithm. The seven polarization-maintained fiber amplifiers are tiled by a collimator array with a high lenslet filling factor (-95%). Total emitting power is -8 kW, and -7.1 kW combined output power is achieved and the contrast of the far-field intensity pattern is measured to be -86% when the system is in the closed loop. This work could provide practical reference on scaling the output power of the tiled aperture coherent beam combining system.

关键词： Phase control Fiber amplifier stochastic parallel gradient descent algorithm

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：