Improved the laser-induced damage threshold of fused silica by atmospheric pressure plasma processing

Fused silica optics are widely used in high-power laser systems and ultraviolet optical systems because of their excellent properties. Laser-induced damage threshold (LIDT) of fused silica is a key problem that limits the improvement of optical systems. Atmospheric pressure plasma processing (APPP) has great promise for improving LIDT because it involves lowcost, non-contact, and high-efficiency material removal based on its pure chemical etching mechanism. However, the deteriorated surface morphology after atmospheric plasma etching limits the further improvement of LIDT of fused silica. This study analyzes the exposure and passivation processes of subsurface scratches during atmospheric pressure plasma processing. The evolution process of interfacial contours related to the etching and deposition process is described. At the end, a series of etching experiments under different dwell times are carried out and a flexible medium polishing processing is used to improve the deteriorated surface quality. The results indicate that the LIDT of fused silica is significantly increased from 8.1 J/cm² to 30.8 J/cm² by APPP and flexible medium polishing processing. APPP is expected to be effective in improving the LIDT of fused silica.