Numerical Simulation of Silicon Laser Ablation with GHz Bursts of Femtosecond Pulses

We simulate laser ablation of silicon with GHz bursts of femtosecond laser pulses using COMSOL Multiphysics. The simple model of deformation geometry is considered to simulate laser ablation and material removal, giving a laser-induced crater after irradiation. We demonstrate that at the same burst pulse energy a deeper crater is ablated for a GHz burst for larger number of intra-pulses. Analysis of the temperature evolution of silicon target reveals that during femtosecond laser irradiation with GHz burst mode, efficient absorption of laser energy occurs due to the heat-accumulation effect. These simulated results show a good agreement with the experimental measurements and could quantitatively explain the mechanism of silicon ablation enhancement with the GHz bursts of femtosecond laser pulses.