基于自相关的纳焦级弱信号10^11高动态范围测量  

10^11 High-Dynamic-Range Measurement for Nano-Joule-Level Weak Signal Based on Autocorrelation

作　　者：孙青丰 李大为[1,3] 王韬 张腾[1,3] 张天雄 徐光 Sun Qingfeng;Li Dawei;Wang Tao;Zhang Teng;Zhang Tianxiong;Xu Guang(Key Laboratory of High Power Laser and Physics,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;Shanghai Institute of Laser Plasma,China Academy of Engineering Physics,Shanghai 201800,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院上海光学精密机械研究所高功率激光物理联合实验室,上海201800 [2]中国工程物理研究院上海激光等离子体研究所,上海201800 [3]中国科学院大学材料与光电研究中心,北京100049

出　　处：《中国激光》2020年第6期167-174,共8页Chinese Journal of Lasers

基　　金：中国科学院国际合作计划(181231KYSB20170022)。

摘　　要：为实现弱信号对比度的高动态范围测量,基于二阶自相关理论,提出了一种实现纳焦级弱信号对比度高动态范围测量的方法。理论分析了能量(功率)、相位匹配和测量噪声对测量动态范围的影响,发现通过对测量噪声能量的光子计数进行探测、精确设置相位匹配过程中的非共线角,并采用聚焦和滤波方式对测量噪声进行抑制,可有效提升测量的动态范围。在此基础上,建立了一台弱信号高动态范围测量系统,利用神光II高能拍瓦激光种子源,实现了纳焦级弱信号1.0×10^11的高测量动态范围,这一数值与理论分析结果相符;同时,实现了种子源4.3×10^8对比度的准确甄别。研究结果对国内高能拍瓦激光系统对比度的提升具有重要意义。To achieve the high-dynamic-range measurement for weak signal,a method of realizing contrast measurement in high dynamic range for nJ-level weak signal is proposed based on second-order autocorrelation.The effects of energy(power),phase matching,and measurement noise are theoretically analyzed.The dynamic range can be effectively enhanced via the photon-counting detection of the measurement noise,selection of non-collinear angle in phase-matching and suppression of measurement noise by focusing and filtering.Thus a high-dynamic-range measurement system is established for a weak signal.A high measurable dynamic range of 1.0×10^11 is achieved for the nJ-level weak signal when using the laser source of the Shenguang Ⅱ high-energy petawatt laser,which is in agreement with the theoretical result.Furthermore,accurate screening is realized for a laser source having a contrast of 4.3×10^8.The obtained results are significant for improving the contrast of the high-energy petawatt laser system.

关 键 词：非线性光学 高动态范围测量 二阶自相关 弱信号 高能拍瓦激光系统 

分 类 号：O437[机械工程—光学工程]