高功率超短脉冲系统等离子体镜的焦斑退化分析  

Focal Spot Deterioration Analysis of Plasma Mirrors in High-Power Ultrashort Laser Systems

作　　者：张栋俊 朱坪 谢兴龙[1] 康俊[1] 杨庆伟[1] 朱海东[1] 郭爱林[1] 孙美智[1] 高奇[1] 朱健强[1] Zhang Dongjun;Zhu Ping;Xie Xinglong;Kang Jun;Yang Qingwei;Zhu Haidong;Guo Ailin;Sun Meizhi;Gao Qi;Zhu Jianqiang(Key Laboratory of High Power Laser and Physics,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)

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]中国科学院大学材料与光电研究中心,北京100049

出　　处：《光学学报》2020年第2期204-213,共10页Acta Optica Sinica

基　　金：中国科学院重点实验室创新基金(CXJJ-2019S015);上海市青年科技英才扬帆计划(19YF1453500)。

摘　　要：等离子体镜是一种有效提升高功率超短脉冲激光信噪比的方法,但在一部分实验中使用等离子体镜后焦斑出现了退化现象。为了定量研究等离子体镜的焦斑退化问题,提出基于等离子体膨胀和衍射传输的时空聚焦多步传输算法,通过光束质量评价函数定量分析等离子体膨胀时间、波前误差幅值和空间频率对焦斑退化的影响。仿真结果表明,等离子体镜引起的远场焦斑退化主要是由等离子体膨胀时间和波前误差引起的等离子体膨胀不均匀所致,其中,等离子体膨胀时间是主导因素。并且波前误差的幅度越大、空间频率越低,对聚焦能力的影响相对越大。从高信噪比、高功率激光系统输出能力的角度考虑,对于使用等离子体镜的高功率超短脉冲激光系统提出时空上的光束质量要求,以避免远场焦斑的退化问题。Plasma mirrors can be effectively used to improve the signal-to-noise ratio(SNR)of high-power ultrashort laser;however,some experiments conducted using plasma mirrors denote that plasma mirrors may cause focal spot deterioration.Herein,we establish a spatiotemporal focusing multistep propagation algorithm based on plasma expansion and diffraction propagation to quantitatively investigate the plasma-mirror-induced focal spot deterioration.Further,the influences of the plasma expansion time as well as the amplitude and spatial frequency of wavefront error on focal spot deterioration are quantitatively analyzed using a beam quality evaluation function.The simulation results reveal that the plasma-mirror-induced far-field focal spot deterioration can be mainly attributed to the non-uniform plasma expansion based on the plasma expansion time and wavefront error,with the plasma expansion time observed to be the dominant factor.Additionally,higher-amplitude and lower-spatial-frequency wavefront errors have a relatively greater influence on the focusing ability.From the perspective of high SNR ultraintense output capability,the spatiotemporal quality requirement of the pulse is introduced to avoid far-field focal spot deterioration when a plasma mirror is used in a high-power ultrashort laser system.

关 键 词：超快光学 等离子体镜 等离子体膨胀 波前误差 傅里叶变换 

分 类 号：O436[机械工程—光学工程]