Ultrashort pulse laser processing of silica at high repetition rates - from network change to residual strain

We report on the analysis of silica-based glasses after processing with ultrashort laser pulses at high repetition rates. Heat accumulation leads to strong local heating of the glass. The subsequent quenching results in a fictive temperature rise that scales with the repetition rate. Consequently, the relative volume change leads to residual tensile strain within the modified volume of larger than 10-3, which is confirmed by wide-angle X-ray scattering (WAXS) measurements. Studying the surface topography after cleaving of laser-modified regions allows for quantification of the corresponding elastic strain as well as the glass density behavior on the fictive temperature.