Short-Pulse Laser Ablation of Solids: From Phase Explosion to Fragmentation

Abstract

The mechanisms of laser ablation in silicon are investigated close to the threshold energy for pulse durations of $500\mathrm{f}\mathrm{s}$ and $50\mathrm{p}\mathrm{s}$. This is achieved using a unique model coupling carrier and atom dynamics within a unified Monte Carlo and molecular-dynamics scheme. Under femtosecond laser irradiation, isochoric heating and rapid adiabatic expansion of the material provide a natural pathway to phase explosion. This is not observed under slower, nonadiabatic cooling with picosecond pulses where fragmentation of the hot metallic fluid is the only relevant ablation mechanism.