Optimisation de l'ablation laser par superposition d'impulsions laser femtoseconde et nanoseconde

This thesis presents experimental results of the ablation of fused silica and alpha-quartz by the superposition of laser pulses with different properties. Experiments were done with a titanium-sapphire laser chain generating high intensity femtosecond laser pulses and a neodium-yttrium-aluminum garnet laser generating nanosecond laser pulses. We measured a strong increase of ablated depth and ejected volume of matter with the superposition of these two pulses trains on silica surface. This increase of ablation is the result of incubation effect from conduction electrons and defects in the lattice generated by the femtosecond laser pulse. The conduction electrons and defects are an initial source of easily excitable electrons by the nanosecond laser pulse for the ionisation of silica by avalanche ionisation.