大型短脉冲激光装置中脉冲前沿畸变效应的研究

Pulse-front-distortion in large-aperture short-pulse laser systems

阐述了短脉冲激光装置中脉冲前沿畸变效应的产生机理和可能的畸变源.利用Fourier光学方法,建立了一个基于单程压缩构型的研究脉冲前沿畸变效应的理论模型,分析不同种脉冲前沿畸变效应对于压缩器输出脉冲的近场时空特性的影响.基于此,对一个在建的大口径(300mm)短脉冲装置中的各种畸变源(包括可编程声光光谱色散滤波器、透镜色差以及劈板等元件)进行了数值计算.研究表明:近场输出脉冲宽度显著加宽,输出脉冲前沿形状不同于输入时的畸变形状,只有中心部分区域的脉冲前沿形状与输入类似,该区域的大小由系统带宽决定.

The principles of pulse-front distortion＇s production and its possible sources in a large-aperture short-pulse laser system are described. By using Fourier optics,a theoretical model based on single-pass compression is set up for the study of the pulse-front distortion. For the first time the effects of the pulse-front distortion on the spatial and temporal properties of the output pulse from the compressor is investigated. With the model we analyze all kinds of distortion sources,including the AOPDF,the lens and the wedges by numerical simulation for a large-aperture short-pulse system. The result shows that the pulse width in the near field broadens remarkably and the pulse-front shape of the output pulse differs from that of the input pulse except in the central part in the cross section whose area is determined by the bandwidth of the system.