复合刻蚀诱导熔石英表面氧空位缺陷演变及损伤性能提升机制研究

Laser-induced damage of fused silica optics is an important factor limiting the development of high-power laser systems. Nowadays, dynamic chemical etching and reactive ion etching have been used for improving the damage performance of fused silica. However, the surface shape and roughness of the optics are deteriorated after dynamic chemical etching with high etching depth, while the damage performance is difficult to be improved during reactive ion etching process due to the generation of chemical-structural, e. g., defects oxygen-deficiency center (ODC). In this project, according to the bottleneck of the two methods, reaction ion etching and dynamic chemical etching are combined aiming at significantly improving the damage resistance of fused silica optics, while minimizing the removal amount so that the surface shape and roughness can be effectively controlled. To deeply investigate the potential of that the combining method improving the damage performance of fused silica, ODC induced by reactive ion etching will be focused on in this project, where the formation, transformation, and removal nature of ODC during the combining etching process will be investigated systematically. The relationship between ODC distribution feature and optical damage will be established in order to reveal the high damage resistance mechanism of fused silica modified by the combining method. The project will give a new technique approach for promoting the damage performance of fused silica and also a mechanism-based support for enhancing the power-loading property of high-power laser systems by combining low-depth-etching process.

熔石英光学元件的激光诱导损伤是限制高功率激光驱动系统发展的一个关键因素。目前，动态化学刻蚀和反应离子刻蚀均被用来提升熔石英元件的损伤性能，但前者在深刻蚀下会导致元件表面粗糙度增加、面型精度劣化，后者次生的氧空位等化学结构缺陷使得元件损伤性能提升幅度严重受限。本项目针对这两种方法的瓶颈问题，将二者有机复合，以较浅的刻蚀深度实现元件损伤性能的大幅度提升，并兼顾粗糙度、面型等光学指标。为了从机理上深入挖掘复合刻蚀对熔石英损伤性能的提升潜力，本项目以反应离子刻蚀次生的氧空位这一关键化学结构缺陷为切入点，系统研究复合刻蚀过程中元件表面氧空位的形成、转变及去除规律，建立氧空位分布特征与光学损伤的内在联系，从而揭示复合刻蚀实现熔石英高抗损特性的内在机制。该项目为熔石英元件损伤性能提升提供了全新的技术途径，并为浅度复合刻蚀技术应用于高功率激光驱动系统的负载能力提升提供机理性支撑。

传统抛光熔石英光学元件的近表面区域可能存在的激光诱导损伤前驱体包括紧密粘附在表面上的外来沉淀物或有机污染物，嵌埋在Beilby层或亚表面层的外来杂质（主要是来自抛光粉的金属元素）和位于破碎表面的内在石英缺陷。本项目基于反应离子刻蚀和动态化学刻蚀的复合处理技术，以较浅的刻蚀深度实现元件损伤性能的大幅度提升，并兼顾粗糙度、面型等光学指标。为了从机理上深入挖掘复合刻蚀对熔石英损伤性能的提升潜力，本项目以反应离子刻蚀次生的氧空位等化学结构缺陷为切入点，系统研究了复合刻蚀过程中元件表面氧空位的形成、转变及去除规律，建立了氧空位等缺陷分布特征与光学损伤的内在联系，从而揭示复合刻蚀实现熔石英高抗损特性的内在机制。该项目为熔石英元件损伤性能提升提供了全新的技术途径，并为浅度复合刻蚀技术应用于高功率激光驱动系统的负载能力提升提供机理性支撑。