Characteristics of Fused Silica Exit Surface Damage by Low-Temporal Coherence Light Irradiation

Laser-induced exit surface damage of fused silica is a key bottleneck for its application in high-power laser devices. As low-temporal coherence light (LTCL) has garnered increasing attention for high-power laser-driven inertial confinement fusion, understanding LTCL-induced exit surface damage of fused silica becomes crucial for improving the output power capability of LTCL devices. In this study, we characterized damage on the exit surface of fused silica under LTCL irradiation and investigated the physical mechanism of temporal coherence affecting the laser-induced damage threshold (LIDT). The relationship between defect information and temporal coherence was explored using a defect analysis model, and the defect damage process and response to each incident lasers were captured using time-resolved methods and artificially fabricated defects. We elucidate the physical mechanism behind the lower LIDT under LTCL irradiation compared to single longitudinal mode (SLM) pulse lasers. This study not only provides the boundary condition for safe fused silica operation in high-power LTCL devices but also offers deeper insight into the physical properties of LTCL.