High-power Yb-based all-fiber laser delivering 300 fs pulses for high-speed ablation-cooled material removal

Abstract

We report on a 72W Yb all-fiber ultrafast laser system with 1.6GHz intra-burst and 200kHz burst repetition rate developed to demonstrate ablation-cooled material removal at high speeds. Up to 24W is applied on Cu and Si samples with pulses of ∼300 fs, and record-high ablation efficiencies are obtained, compared to published results to date, despite using only ∼100 nJ pulses. Ablation speeds approaching 1 mm3/s are reported with 24W of average power, limited by available laser power and beam scanning speed. More significantly, these results experimentally confirm the theoretically expected linear scaling of the ablation-cooled regime to higher average powers without sacrificing efficiency, which implies that further scaling is possible with further increases in laser power and scanning speeds.