Non-thermal and thermal processes in the ultra-short laser ablation of sapphire

Summary form only given. The purpose of this study is to distinguish between non-thermal and thermal processes that lead to laser ablation of wide band-gap dielectrics (in our case sapphire) under ultrashort (sub-ps and ps) infrared laser pulse irradiation. Two ablation phases, a gentle-etch phase and a strong-etch phase, have been distinguished in the process of laser sputtering as a function of pulse duration, laser fluence and number of pulses, which are regarded as the key parameters that govern the laser-induced ablation process. We focus our attention on the non-thermal processes directly related to particle emission, as a consequence of the electronic processes that initiate and mediate the laser interaction.