电子束蒸发制备HfO_2/SiO_2高反膜的1064 nm激光预处理效应

1064 nm Laser Conditioning Effect of HfO_2/SiO_2 High Reflectors Deposited by E-Beam

激光预处理是提高薄膜元件抗激光损伤阈值的重要手段。对电子束蒸发HfO_2,SiO_2块状材料镀制的基频高反膜进行了1-on-1和R on-1阈值测试,比较分析了两种测试情况下出现的典型损伤形貌。实验发现,R-on-1测试表现出明显的预处理效应,其所测抗激光损伤阈值是1-on-1测试的3倍;1-on-1测试下的典型损伤形貌是围绕平底小坑的等离子烧蚀损伤,R-on-1测试下的典型损伤形貌仅是表面等离子体烧蚀损伤;表面轮廓测试的结果表明两种损伤形貌的烧蚀区域中心都是凸起的。两种典型损伤破坏形貌及其差异的研究说明吸收性缺陷是引起此样品损伤的主要诱因,预处理对吸收性缺陷的力学稳定作用是此样品抗激光损伤阈值提高的宏观原因。

Laser conditioning is one of the important methods to improve the laser damage threshold of film optics. First, both 1-on-1 and R-on-1 test are done on the fundamental frequency high reflectors, which are evaporated from hafnia and silica by e-beam. Next, the typical damage morphologies occurred in the two measurements are compared and analyzed. Obvious laser conditioning effect is observed in the R-on-1 test, the damage threshold of which is three times larger than that of 1-on-1 test. The typical morphology in 1-on-1 test is plasma scalding with a central flat- bottom pit and the typical morphology in R-on-1 test is plasma scalding only. The results of surface profiler measurement show that all the centers of the plasma scalds that occurred in the above two typical damage morphologies are raised. The two different damage morphologies imply that absorbing defect is the inducement of the damage and the macroscopical reason for the improved laser damage threshold in R-on-1 test, is presented as the mechanic stability of absorbing defects.