Fabrication of spherical mitigation pit on KH2PO4 crystal by micro-milling and modeling of its induced light intensification
Fabrication of spherical mitigation pit on KH2PO4 crystal by micro-milling and modeling of its induced light intensification
复制标题
通过微铣削在 KH2PO4 晶体上制作球形缓解坑并对其诱导光增强进行建模
DOI：
10.1364/oe.21.016799
复制
发表时间：
2013-07-15
期刊：
影响因子：
3.8
通讯作者：
Li, Mingquan
中科院分区：
文献类型：
--
作者：
Cheng, Jian;Chen, Mingjun;Li, Mingquan
在高功率激光系统中，微加工是KH_2PO_4晶体抑制表面损伤生长的最有前途的方法。本文采用微细铣削技术，采用高效的加工工艺，加工出球形缓蚀坑。基于时域有限差分方法，对缓解前后后表面特征引起的光增强进行了数值模拟。结果表明，晶体内部光强度最大的原因应该是全内反射的发生。对于缓解后的球形凹坑，通过防止全内反射的发生，可以大大缓解光强。球形缓蚀坑的光强效应强烈依赖于宽深比，建议球形缓蚀坑的宽深比必须大于5.0，才能达到最小的光照强度，从而减缓地表损伤的发展。通过对KH_2PO_4晶体的激光损伤试验，验证了用预先设计的缓蚀坑代替初始损伤部位，可以将初始损伤表面的抗激光损伤能力恢复到接近理想表面的水平。(C)2013年美国光学学会
Micro-machining is the most promising method for KH2PO4 crystal to mitigate the surface damage growth in high power laser system. In this work, spherical mitigation pit is fabricated by micro-milling with an efficient machining procedure. The light intensification caused by rear surface features before and after mitigation is numerically modeled based on the finite-difference time-domain method. The results indicate that the occurrence of total internal reflections should be responsible for the largest light intensification inside the crystal. For spherical pits after mitigation, the light intensification can be greatly alleviated by preventing the occurrence of total internal reflections. The light intensification caused by spherical mitigation pit is strongly dependent on the width-depth ratio and it is suggested that the width-depth ratio of spherical mitigation pit must be devised to be larger than 5.0 to achieve the minimal light intensification for the mitigation of surface damage growth. Laser damage tests for KH2PO4 crystal validate that the laser damage resistance of initially damaged surface can be retrieved to near the level of ideal surface by replacing initial damage site with predesigned mitigation pit. (C) 2013 Optical Society of America