Light-field-enhanced laser damage model for polishing-produced particles in fused silica optical surface

A photothermal damage model of nanoparticles in polished fused silica surface is proposed based on light-field modulation effect. The influences of the size, aggregation characteristics, and distribution density of the polishing-produced particles on photothermal damage performance of fused silica were studied theoretically and experimentally. The results show that the light-field enhancement, even for CeO2 particles smaller than 10 nm, greatly impacts the thermal distribution and critical laser energy density of fused silica. For a single 50-nm CeO2 particle in the surface of fused silica, the light-field enhancement can increase the material temperature by 34.20 % while decrease the critical laser energy density (@355 nm, 3 ns) by 26.00 % in comparison with the situation where the light-field enhancement effect is not considered. Moreover, large ceria particles (typically a ≥20 nm) are found to readily form high-density low-fluence damage precursors. And the high-density aggregated particles, especially the tangent particles, are also key factors limiting the damage performance enhancement of fused silica. The results could contribute to theoretical support for better understanding of the mechanism of fused silica damage induced by polishing particles.