皮秒拍瓦激光系统宽带激光放大的精确模型和性能分析  

Accurate model and performance analysis of broadband pulsed amplification in picosecond petawatt laser system

作　　者：李大为[1,5] 王韬 尹晓蕾[3] 李佳美 王利 张腾[1,5] 张天雄 崔勇 卢兴强[1] 王丽[4] 张杰 徐光 Li Da-Wei;Wang Tao;Yin Xiao-Lei;Li Jia-Mei;Wang Li;Zhang Teng;Zhang Tian-Xiong;Cui Yong;Lu Xing-Qiang;Wang Li;Zhang Jie;Xu Guang(Joint 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;Changzhou Institute of Technology,School of Sciences,Changzhou 213032,China;Shanghai Institute of Laser Technology,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]常州工学院理学院,常州213032 [4]上海市激光技术研究所,上海201800 [5]中国科学院大学材料科学与光电研究中心,北京100049

出　　处：《物理学报》2021年第10期126-134,共9页Acta Physica Sinica

基　　金：张江国家自主创新示范区专项发展资金重点项目(批准号:ZJ2020-ZD-006)资助的课题.

摘　　要：为准确分析皮秒拍瓦激光系统的频域放大特性,通过引入钕玻璃实际受激发射截面,建立了宽频带激光放大的精确模型,对比分析了常用高斯线型近似的不足.针对神光Ⅱ高能拍瓦激光系统,分析了不同线型下,注入种子的光谱形状、中心波长以及能量稳定性对放大系统的影响.结果表明:实际线型会加剧增益窄化效应;对于10^(7)增益,光谱将窄化为3 nm,系统累积B积分增大至1.7;窄化效应降低了注入种子中心波长的要求,增益饱和会使输出能量稳定性提升近一倍.在上述基础上,进行了宽频带激光放大的实验研究,对于注入的10 nm(FWHM)超高斯、1054 nm中心波长、3%(RMS)稳定性的参量放大种子,实现了1900 J、中心波长1054.2 nm、谱宽3 nm的输出,发次能量稳定性<1.8%,与分析结果一致.本文结果将对国内基于钕玻璃的高能宽带激光装置建设和改进提供重要的参考依据.In order to accurately analyze the broadband pulsed amplification performances of the domestic picosecond petawatt laser system,which uses large aperture N31 or N41 neodymium glass as gain medium,the broadband pulsed amplification model is improved by introducing the actual stimulated emission cross section(SECS)of neodymium glass.Comparing with the SECS under Gaussian approximation,the amplified pulsed spectrum gain narrowing effect with different SECSs are analyzed.It is found that in the actual SECS of N31 neodymium glass laser,the gain-narrowing effect is enhanced,the output energy decreases,gain’s saturation effect weakens,system’s accumulated B integral augments,but the laser system turns insensitive to the center wavelength simultaneously.Based on the Shenguang Ⅱ high energy picosecond petawatt laser system which uses N31 neodymium glass,the spectral shape,center wavelength,and energy stability of amplified output pulse are simulated by using different SECSs.It is shown that the super-Gaussian spectral shape narrows more greatly than Gaussian spectral shape,the spectrum bandwidth narrows from 10 to about 3 nm with gain larger than 107,and the accumulated B integral increases to 1.7.Additionally,the gain-narrowing effect makes the output spectrum(with 1054 nm of center wavelength)less affected by changing the inputted center wavelength from 1052 to 1056 nm,and the gain saturation effect can improve output energy stability to less than 2%(root mean square(RMS))with about 3%(RMS)inputted energy stability,which are beneficial to the subsequent pulse compression and physical experiment.Based on the above analysis,a broadband pulsed amplified experiment is conducted by using Shenguang II petawatt laser system,the injected seed is about 10 nm(full width at half maximum(FWHM))with 5 order super Gaussian shape at 1054-nm center wavelength,and 1.2 mJ with 3%(RMS)energy stability from optical parametric chirped pulse amplification.The amplified pulse with 1900 J at 1054.2 nm(3 nm FWHM)and stability<2%(shot to s

关 键 词：皮秒拍瓦激光系统 宽频带激光 钕玻璃 受激发射截面 增益窄化 

分 类 号：TN24[电子电信—物理电子学]