Guidelines for efficient direct ablation of dielectrics with single femtosecond pulses

Abstract

We provide guidelines to femtosecond laser users to select ad hoc laser parameters, namely the fluence and pulse duration, in the context of the development of ablation processes at the surface of dielectrics using single femtosecond pulses. Our results and discussion are based on a comprehensive experimental and theoretical analysis of the energy deposition process at the surface of fused silica samples and of their postmortem ablation characteristics, in the range of intensities from 1013 to 1015 W/cm2. We show experimentally and numerically that self-induced plasma transient properties at the pulse timescale dramatically determine the efficiency of energy deposition and affect the resulting ablation morphology. In practice, we determine that the precise measurement of two characteristic fluence values, namely the laser-induced ablation threshold F th,LIAT and the fluence F opt for maximum ablation efficiency, are only required to qualify the outcomes of laser ablation at the surface of a dielectric in an extended range of applied fluence.