摘要
在大型超快超强激光系统中,随着光谱带宽及光束口径的增加,时空耦合畸变会变得越来越显著,该效应不仅会使光束质量恶化、影响激光的聚焦功率密度,而且会使常规的激光远场性能的评估手段失效.本文以激光器中常用的扩束透镜组为例分析了时空耦合畸变给激光参数测量及激光性能评估带来的影响.结果表明,在一个超短脉冲激光系统中,一对普通的扩束透镜组引入的时空耦合畸变不仅会使远场峰值功率密度急剧下降,还会导致单次自相关仪在近场处测得的脉宽与远场处的实际脉宽相差超过10倍,而这种情况下利用近场脉宽测试值估算远场处的聚焦功率密度会比真实值高出一个量级.研究结果可以为激光器的优化设计、激光脉冲参数的精确表征以及相关的物理实验提供参考.
In a large-scale ultra-fast and ultra-intensity laser system,with the increase of spectral bandwidth and beam aperture,the spatiotemporal coupling distortion will become more and more significant.This effect will not only degrade the beam quality and reduce the focusing intensity of the laser,but also invalidate the conventional evaluation method for laser far-field parameters.A pair of beam-expanding lenses,which may bring spatiotemporal coupling distortion to an ultrashort laser pulse,is taken as an example.And the influence of spatiotemporal coupling distortion on laser parameter measurement is analyzed in detail.It shows that in an ultrashort pulse laser system,an ordinary beam-expanding lens-pair can reduce the far-field peak intensity dramatically,and the actual pulse duration in the far field is more than 10 times longer than that measured at the near field by a single-shot autocorrelator.In this case,the focusing intensity estimated by using the measured value of near-field pulse width will be one order of magnitude bigger than the real value.It is expected that the results will be helpful in the optimal design of a laser system,the accurate characterization of an ultrafast laser pulse and relevant physical experiments.
作者
龙天洋
李伟
许浩天
王逍
Long Tian-Yang;Li Wei;Xu Hao-Tian;Wang Xiao(College of Physics,Sichuan University,Chengdu 610044,China;Research Center of Laser Fusion,China Academy of Engineering Physics,Mianyang 621900,China;Department of Optics and Optical Engineering,University of Science and Technology of China,Hefei 230026,China;School of Space Science and Physics,Shandong University,Weihai 264000,China;Graduate School of China Academy of Engineering Physics,Beijing 100088,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第17期218-226,共9页
Acta Physica Sinica
基金
国家重点研发计划(批准号:2018YFA0404804)资助的课题.
关键词
超快激光
时空耦合畸变
单次自相关
ultrafast laser
spatiotemporal coupling aberration
single-shot autocorrelation
