Hydrodynamic simulation of silicon ablation by ultrashort laser irradiation

Ultrashort (10 fs–100 ps) pulse laser ablation of pure silicon in vacuum was simulated by using a modified self-consistent one-dimensional hydrodynamic code to study the fundamental ablation mechanisms. The presented results provide a guide for drilling periodic microholes or microgratings on the dense insulator surface. The simulated laser ablation threshold remains nearly constant in femtosecond regime, and increases as the square root of pulse duration in picosecond regime. The ablation depth as a function of pulse duration shows four different regimes and the ablation depth reaches a minimum when the pulse duration is ∼30 ps at various laser fluences. The influence of laser-induced plasma shielding on ablation depth was also studied.