Dynamic process of nanosecond laser damage of fused silica

The dynamic process of nanosecond laser induced damage of fused silicas input-surface, output-surface and bulk in air was investigated by ultrafast time-resolved shadowgraphs. The comparison and analysis of the damage mechanisms of the input-surface, output-surface and bulk were performed. On the input-surface, the generation and development process of plasma and shock wave were observed in air and materials, three stress waves were observed in materials under the subnanosecond laser, and the bulk damage was observed near the input-surface. On the output-surface, the images of material ablation, explosive phase change and shock waves were obtained. In the bulk, the results show that both the self-focusing and the absorption of point defect are answerable for the damage. However, the damage beginning due to the absorption of point defect maybe has temporal difference.