超相干长度的激光相干探测性能研究  

Research on Laser Coherent Detection with a Super-Coherence Length

作　　者：潘含蕊 卢智勇[1] 孙建锋[1,3,4] 周煜 贺红雨[1] 许玲玲[1] 李超洋 任伟杰 姜玉鑫 张龙坤 贾弘辉 袁浩铭 Pan Hanrui;Lu Zhiyong;Sun Jianfeng;Zhou Yu;He Hongyu;Xu Lingling;Li Chaoyang;Ren Weijie;Jiang Yuxin;Zhang Longkun;Jia Honghui;Yuan Haoming(Key Laboratory of Space Laser Communication and Detection Technology,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;Shanghai Satellite Network Research Institute Company Limited,Shanghai 200120,China;Shanghai Key Laboratory of Satellite Network,Shanghai 200120,China;Aerospace Laser Technology and System Department,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China)

机构地区：[1]中国科学院上海光学精密机械研究所空间激光传输与探测技术重点实验室,上海201800 [2]中国科学院大学材料与光电研究中心,北京100049 [3]上海卫星互联网研究院有限公司,上海200120 [4]上海市卫星互联网重点实验室,上海200120 [5]中国科学院上海光学精密机械研究所空天激光技术与系统部,上海201800

出　　处：《中国激光》2024年第19期275-284,共10页Chinese Journal of Lasers

基　　金：卫星互联网开放基金;国家重点研发计划(2020YFB0408302);国家自然科学基金(91938302)。

摘　　要：为实现大宽带频率范围的探测,提出一种基于本振可调谐的相干激光雷达方案,通过调谐激光频率,降低了探测器和采集硬件的采样压力,并通过相位测量和相位估计迭代等方式对回波信号进行相位补偿,最终实现对远距离弱信号目标的探测。系统分析了相干激光探测系统的各个环节(激光器、调制器、传输路径等)对系统相干性的统一影响,采用斯特列尔比来表征相干探测系统的相干性劣化程度,以及相干探测系统的相干时间(相干长度)情况。仿真结果表明,相干探测系统的相干性及探测精度会受到激光器、相位调制、距离延迟等环节的相位影响。通过实验验证,当积分时间为0.7 ms、回波信号功率为11 fW时,相干探测系统的探测概率为52%,信噪比为10.1 dB,速度精度为11.4 cm/s;经相位补偿后,探测概率为74%,信噪比为19.8 dB,速度精度为0.16 cm/s;在经过更长的积分时间后,实现了更好的探测性能。综合结果表明,相干激光雷达在超相干长度下,经过相位补偿后,系统仍具有高灵敏度、高探测精度等特性,为后续进一步开展超相干长度下的远距离弱信号目标探测提供可行的实验依据,具有重要的研究意义。Objective Coherent lidar uses coherent detection technology to probe target information.The echo signal is mixed coherently with a local oscillator signal to detect the target using the heterodyne detection method.The beat frequency signal is then analyzed to obtain the velocity and distance information of the target.However,a coherent detection system is affected by various factors,such as lasers,phase modulation,transmission distance,and atmospheric turbulence,during the detection process.This leads to the introduction of phase disturbances into the echo signal,consequently compromising the coherence of the coherent detection system,which significantly affects the detection capability of the coherent lidar.Maintaining system coherence is crucial to ensure high detection sensitivity and precision in coherent detection systems.Therefore,research on the coherence of coherent detection systems is crucial.By studying the coherence of a coherent detection system,we can determine the coherence length or time of the coherent lidar,thereby obtaining the maximum detection range and maximum coherent integration time of the coherent detection system.Additionally,the coherence of a coherent detection system should be restored by compensating for the effects of phase disturbances.Through phase compensation,the coherence of a coherent detection system can be restored,thereby enhancing its detection performance of coherent detection system.Methods This paper evaluates the overall coherence of a coherent detection system using the Strehl ratio and calculates the coherence time of the system based on the Strehl ratio.By designing a coherent detection system with two lasers as separate local oscillators and transmitting laser sources,velocity detection is simulated under the condition of the super-coherence length in actual detection.An acousto-optic frequency shifter and attenuator are employed to simulate the Doppler frequency and signal attenuation after transmission over distances exceeding the coherence length.Moreover,phase

关 键 词：激光技术 相干探测系统 相干时间 斯特列尔比 频率漂移 相位补偿 

分 类 号：O436[机械工程—光学工程]