OPCPA系统中光栅对不平行度对脉冲时间波形的影响

 利用光线追迹法和四阶龙格-库塔法分析了光参量啁啾脉冲放大系统中实际展宽器和压缩器所带来的各阶色散，并将其代入放大过程数值模拟了脉冲变化的情况，讨论了压缩器光栅对表面不平行、刻线不平行、信号光强度、泵浦光强度等因素对输出脉冲宽度和时间波形的影响。结果表明，光栅对表面不平行将引起脉冲宽度变大，且光栅顺时针旋转对脉冲宽度和波形影响更大。而光栅刻线不平行时，当仅考虑二阶色散时，夹角为0.8°时脉宽最小，考虑到三阶色散时，夹角为1°脉宽最小，且光栅顺时针和逆时针旋转对脉冲的作用相同。对实际OPCPA系统，当放大晶体材料及长度一定时，尽量调整压缩器光栅平行，信号光强度和泵浦光强度有一最佳值能使输出脉冲宽度达到最小。

Effect of misalignment of grating pair on temporal profiles of ultra-short pulse in OPCPA system

The dispersions resulted from practical stretcher and compressor in optical parametric chirped pulse amplify system are studied by ray-tracing method, and the pulse amplify is numerically simulated using Runge-Kutta method. The effects of misalignment of grating planes and grooves, signal intensity and pump intensity are discussed. The simulations show that misalignment of gating planes leads to pulse broadening. When the angle of grating groove is 0.8°, the pulse width is the narrowest in the case of group delay dispersion. When the angle of grating groove is 1°, the pulse width is the narrowest in the case of three-order dispersion.