实现惯性约束聚变(ICF)需要高质量的远场,而远场是由聚焦前光束的相位和振幅决定的。对高功率固体激光装置,其输出光束的振幅分布主要由注入光束的振幅分布决定,其相位分布主要决定于光路中存在的大口径光学元件,同时高通量运行时的振幅和相位噪声的非线性自聚焦效应对光束远场的影响也不能忽略。基于这些特点,理论分析了影响光束远场的因素以及在高通量下噪声纹波的非线性自聚焦效应,模拟了具有四程放大结构的高功率激光装置的传输特性,分别研究了注入光束振幅和光学元件引入的相位噪声对光束远场的影响。研究表明,大口径光学元件引入的相位噪声是影响远场的主要因素。

High quality far-field determined by the phase and amplitude distribution of focal beam is necessary for inertial confinement fusion (ICF). To the high power laser system, the amplitude distribution of the output laser beam mainly derives from input beam, while phase distribution mainly come from the large aperture optical elements, especially for the Nd:glass amplifier slab. Nonlinear self-focusing of ripple can effect on far field in high energy too. Based on these factor, the transmit character of high power laser with fourth-pass amplifier was simulated, and the effect of amplitude and phase distribution on far field was analyzed by numerical was. The conclusion is that the most important effect factor on far field is phase distortion come from large aperture optics.