SiO2保护膜对高反膜激光损伤特性的改善

 为了研究高功率系统中高反膜的损伤机制，对高功率系统中最常用的基频高反膜进行了损伤实验。利用台阶仪、扫描电镜、表面轮廓仪等手段，对实验样品的典型损伤形貌进行了比较和分析。结果表明：保护膜的存在增强了样品的抗激光损伤能力；未加保护膜样品的典型破坏形貌是由材料热物特性差异导致的分层剥落损伤，这类损伤在后续的脉冲辐照下会迅速发展；有保护膜样品的典型破坏形貌是中心带有μm量级小坑的等离子体烧蚀损伤区，其主要是由缺陷受热力作用喷溅导致，小坑附近膜面的凸起是这种力学作用的宏观体现，这类损伤在后续的脉冲辐照中表现得相对比较稳定。保护膜的存在，在一定程度上抑制了分层剥落这种灾难性损伤的出现，改善了样品的损伤特性。

Damage characteristic improvement of high reflectors by SiO2 overlayer

In order to study the damage mechanism of high reflectors in high power laser systems, laser damage experiments are carried out on fundamental frequency high reflectors which are widely used in high power laser systems, and then the typical morphologies are compared and analyzed by means of step profiler, scanning electron microscope and surface profiler. The results show that the laser resistance is enhanced because of the SiO2 overlayer; typical damage morphology of the sample without silica overlayer is delamination, which is related to the thermal characteristics of materials, and delamination grows quickly during the subsequent laser irradiation; typical damage morphology of the sample with silica overlayer is plasma ablation with a pit in its center, which is related to the thermal