A Two-Step Model for Multiple Picosecond and Femtosecond Pulses Ablation of Fused Silica

Abstract

The morphology of microchannels machined by multiple ultrafast laser pulses with 500 fs and 8 ps durations on fused silica plate is predicted by a two-step model with experimental validation in present work. A spike structure at crater boundary with different scales in 500 fs and 8 ps pulse ablation is found in the numerical investigation, which could be attributed to diffraction and attenuation of light intensity in both cases. To analyze the evolution of crater morphology and damaged area with an increasing number of pulses, the distribution of light intensity, lattice temperature, and self-trapped excitons density during certain pulses are studied. The results showed that 500 fs pulses lead to smoother crater boundary, smaller heat affected zone, and larger electrical damage area with respect to 8 ps pulses.