Evolution of physical and mechanical properties of fused silica after subsurface damage layer removal by RIE treatment

The subsurface damage of polished fused silica can be removed by various post-treatments to improve the strength of fused silica in high energy laser systems, but the evolution of physical and mechanical properties of fused silica after the removal of subsurface damage remains unclear. In this study, the physical and mechanical properties of fused silica are studied after various depths of subsurface damage removal by reactive ion etching process. The results show that as the etching depth increases, the concentration of metal ions contamination in the subsurface of fused silica decreases significantly, the water contact angle of fused silica decreased, while homogeneity of adsorbed water molecules on fused silica surface increases, especially at higher humidity conditions. Furthermore, the nanohardness and reduced modulus of fused silica increases with the etching depth. These results will be helpful for optimizing the manufacturing and lifetime of fused silica in high energy laser systems.