Nanosecond-to-femtosecond laser-induced breakdown in dielectrics

Abstract

We report extensive laser-induced damage threshold measurements on dielectric materials at wavelengths of 1053 and 526 nm for pulse durations (Formula presented) ranging from 140 fs to 1 ns. Qualitative differences in the morphology of damage and a departure from the diffusion-dominated (Formula presented) scaling of the damage fluence indicate that damage occurs from ablation for (Formula presented) ps and from conventional melting, boiling, and fracture for (Formula presented) ps. We find a decreasing threshold fluence associated with a gradual transition from the long-pulse, thermally dominated regime to an ablative regime dominated by collisional and multiphoton ionization, and plasma formation. A theoretical model based on electron production via multiphoton ionization, Joule heating, and collisional (avalanche) ionization is in quantitative agreement with the experimental results. © 1996 The American Physical Society.