Laser damage precursors in fused silica and mitigation process

The laser damage precursors in fused silica were systematically isolated and identified. The paper shows laser damage micrographs from different precursors which are formed during fabrication. Conventionally polished and subsequently scratched fused silica plates were treated by submerging in various HF-based etchants (HF, or NH4F and HF at various ratios and concentrations) under different process conditions. With the optimized etch process, laser damage resistance increased dramatically; the average threshold fluence for damage initiation for fused silica increased from 4.8 to 11.0 J/cm2.