二次谐波转换对激光脉宽影响的实验研究

Study on the effect of second harmonic conversion on the pulse width

摘要: 实验研究了KDP晶体二次谐波转换非线性效应对脉宽测量精度的影响。结果表明：在小信号近似下，长度为1～3cm的KDPⅡ类晶体，对于近高斯脉冲，其基频脉宽与倍频脉宽存在21/2的关系；对于非近高斯脉冲，基频脉冲半宽与倍频脉冲波形的1/4高宽相等；在输入功率密度和能量转换效率较高时，基频与倍频脉宽无固定关系。

Abstract: The non-linear 2ndharmonic conversion effect of the KDP crystal is researched and its effect to measurement accuracy of the laser pulse width. Experimental results show that: in condition of small signal and Gaussian beams, the 1stharmonic laser pulse width is times of that of the 2ndharmonic one with type Ⅱ KDP crystal whose thickness is 1～3cm; Due to the nonGaussian beams, the halfwidth of the 1stharmonic pulse equals to the quarter width of the 2ndharmonic pulse. With higher power density and energy conversion efficiency, the rate between the 1stharmonic pulse width and the 2ndharmonic one vary seriously．