Measuring the deterministic character of laser damage of dielectrics in ultrashort pulsed regime

In this work, the authors propose a direct and quantitative measurement of the deterministic character of femtosecond laser-induced damage in fused silica. For pulses ranging from 7 fs to 450 fs, and with combined experimental procedures enabling to measure both the laser-induced damage and ablation thresholds, the paper presents an experimental measurement of the determinism strength for material damaging, corresponding to the transition slope of the damage probability curve as a function of laser fluence. All the experiments have been done on fused silica (Suprasil) and with a similar damage setup and diagnostics, and beam parameters (single-shot regime, beam waist ~5-10 mum, linear polarization) to ensure a reliable comparison. The results indicate that the laser damage occurrence is more deterministic below 30 fs, associated with a better "photon efficiency" for material removal . These investigations also provide a physical insight and control over important laser processes parameters like damage/ablation threshold fluence, crater shape, and extension of heat-affected zone.