Laser ablation of fused silica induced by gold nano-particles comparison of simulations and experiments at λ=351 nm

Simulations of laser-fused silica interactions at 0.351 m are a key issue in predicting and quantifying laser damage in large laser systems such as LIL and LMJ. Validation of numerical simulations requires detailed knowledge of the different parameters involved in the interaction. To concentrate on a simple situation, we have made and tested a thin film system based on calibrated gold nanoparticles (0.2-0.8 m diameter) inserted between two silica layers. The fused silica overcoat was either 2 or 10 microns thick. We have performed simulations of laser energy deposition in the engineered defect (i.e. nanoparticle) and thesurrounding fused silica taking into account various laser/defect induced absorption mechanisms of SiO2 (radiative ionization, avalanche and multiphotonic ionization). We have studied crater formation produced by the absorber explosion with a 2D Lagrange-Euler code taking into account crack formation and propagation in the brittle material. We discuss the influence of the defect depth (with respect to the surface) on the damage morphology. The simulations are compared with our experimental results.