Benefits of sub 100 fs pulses for laser micromachining of glasses and crystals

Reliable industrial femtosecond lasers deliver pulse durations from 200 fs to 1000 fs. External pulse compression can shorten these pulses to below 100 fs with about 90% efficiency. In a basic study, we demonstrated improved edge quality in glass using 60 fs pulses at a 1030 nm wavelength and 800 kHz repetition rate. For sapphire (28 W) and fused silica (23 W), energy-specific volumes remained close to those of longer pulses, at 8 µm³/µJ and 6.5 µm³/µJ, respectively. We will extend this study to materials like Borofloat 33 and SF2, optimizing surface roughness, stress-induced birefringence, and minimum structure dimensions for sapphire and fused silica as well. These results will be compared to standard 310 fs experiments with IR (1030 nm), green (515 nm), and UV (343 nm) radiation. Additionally, we will investigate pulses as short as 30 fs, frequency-doubled 60 fs pulses and burst mode, focusing on edge quality, surface roughness, and stress-induced birefringence.