Influence of the Repetition Rate and Pulse Duration on the Incubation Effect in Multiple-Shots Ultrafast Laser Ablation of Steel

Abstract

We report on an experimental study of the incubation effect during laser ablation of stainless steel with fs- and ps-pulses at high repetition rates. Ablation thresholds for multiple pulses N have been estimated. As expected, the ablation threshold decreases with N due to damage accumulation. The related incubation coefficient has been determined at different repetition rates, from 50-kHz to 1-MHz and two pulse durations: 650-fs and 10-ps. Results show that the incubation effect is lower for fs-pulses below 600 kHz. At higher repetition rates incubation is more pronounced regardless of the pulse duration, probably due to heat accumulation.