Laser-induced damage in dielectrics with nanosecond to subpicosecond pulses.

Abstract

We report extensive measurements of damage thresholds for fused silica and calcium fluoride at 1053 and 526 nm for pulse durations $\ensuremath{\tau}$ ranging from 270 fs to 1 ns. Qualitative differences in the morphology of damage and a departure from the diffusion-dominated ${\ensuremath{\tau}}^{1/2}$ scaling indicate that damage results from plasma formation and ablation for $\ensuremath{\tau}\ensuremath{\le}10$ ps and from conventional melting and boiling for $\ensuremath{\tau}>100$ ps. A theoretical model based on electron production via multiphoton ionization, Joule heating, and collisional (avalanche) ionization is in good agreement with experimental results.