Enhanced ablation efficiency using GHz bursts in micromachining fused silica

We report on micromilling cavities into fused silica by a 1030 nm femtosecond laser using 2.17 GHz bursts. The milled cavities show an increased depth per layer for a higher number of pulses per burst while the ablation efficiency is also increased. The maximum ablation efficiency for the optimum fluence achieved in our experiments is 3.05 mm(3)/min/W for a burst number of 10, which is 7.4 times higher than for the non-burst condition (0.41 mm(3)/min/W). Furthermore, the ablation threshold for each sub-pulse is significantly reduced from 0.64 J/cm(2) for the non-burst condition to 0.15 J/cm 2 for 10 bursts. Beside the ablation efficiency, the surface roughness is also increased with the increasing burst number, while two ablation behaviors can be distinguished, namely, a gentle ablation regime for lower burst numbers and a coarse ablation regime, dominated by breaking out the surface rather than ablating it. (C) 2021 Optical Society of America

Automated summary

The study on micromilling cavities into fused silica using a femtosecond laser showed that increasing the number of pulses per burst led to increased depth per layer and ablation efficiency. The maximum ablation efficiency achieved in the experiments was 3.05 mm(3)/min/W for a burst number of 10, which was 7.4 times higher than for the non-burst condition.