Femtosecond laser figuring and polishing of fused silica with GHz-burst mode [Invited]

We demonstrate high-precision femtosecond laser polishing and figuring of fused silica using both kilohertz non-burst and gigahertz burst configurations, achieving sub-nanometer surface roughness and nanometer-scale material removal precision simultaneously. The gigahertz burst mode enhances both efficiency and throughput; with a ten-pulse burst configuration, we achieve a 47% increase in ablation rate and a one-third reduction in processing time compared to the non-burst mode. To the best of our knowledge, this is the first demonstration of fused silica polishing using femtosecond lasers, with the GHz configuration paving the way for ultrafast laser fabrication of high-performance optics.