Energy transport and material removal in wide bandgap materials by a femtosecond laser pulse

A new model is proposed which greatly improves the accuracy in predicting the ablation depth and, for the first time, can predict the flat-bottom crater shape for wide bandgap materials ablated by a femtosecond laser pulse. The model calculates the transient distributions of free electron density and free electron temperature. The quantum treatment is employed to account for the specific heat and the relaxation time for free electrons. The temporal and spatial dependent optical properties of the dense plasma are considered. The predicted threshold fluence and ablation depth for fused silica are in agreement with published experimental data.