Raman studies of micro-machine glasses with variable repetition rates

Structural changes in borosilicate and fused silica glasses modified by a femtosecond laser at different laser repetition rates were investigated. The sample was submitted to femtosecond laser pulses at a rate ranging from 1 kHz to 25 MHz in the regime where the sample could experience from a rapid cooling to a cumulative heating respectively. Changes in the glass networks of the modified region were recorded via Raman microscopy using an Ar laser at 514 nm as an excitation. Due to fluorescence background in fused silica, relative peak intensities at 605 cm-1 800 cm-1 were observed for changes. No fluorescence backgrounds were observed in borosilicate samples allowing observation of changes for individual peaks around 600 cm-1, 800 cm-1 and 1100 cm-1. Possible mechanisms will be discussed.