KDP晶体激光预处理参数的优化

Laser pretreatment parameters optimization of KDP crystal

KDP晶体是目前高功率激光装置中倍频材料的首选,元件上架前通常采用激光预处理来提高抗激光损伤性能,由于预处理流程耗时较多,提升预处理效率对于工程应用具有重要意义。研究了激光预处理参数对KDP晶体材料损伤性能的影响,通过分析激光辐照通量、辐照发次、能量台阶等预处理参数与元件损伤性能的变化关系,发现在一定通量范围内用不同的能量台阶可以获得同样的预处理效果,由此确定采用变能量台阶的方法对预处理参数进行优化。实验证明,采用此方法可以在保证预处理效果的前提下,将总的激光辐照发次缩减三分之一,结果对于大口径KDP晶体元件的激光预处理工艺具有重要参考价值。

KDP crystal is the chief choice of frequency multiplier in high power laser system. Laser pretreatment is usually used to improve the damage probability of KDP element, the pretreatment process is more time-consuming, and it is of great significance to the engineering application to improve the pretreatment efficiency. KDP damage performance preconditioned by different laser pretreatment protocols was investigated, every protocol had three key parameters： laser radiation fluence, irradiated laser shots, and energy steps. By analyzing the condition parameters and the resultant damage performance, effect of every parameter on damage performance was discovered, and it is found that the same pretreatment performance can be achieved by using different energy steps, and laser pretreatment protocol was optimized by using variable energy steps instead of fixing one. Experimental results show that the variable energy steps protocol achieves total laser shots savings of 33%. The results would be benefit for KDP elements pretreatment process.