Formation of laser-induced periodic surface structures on fused silica upon two-color double-pulse irradiation

The formation of laser-induced periodic surface structures (LIPSS) upon irradiation of fused silica with multiple irradiation sequences consisting of laser pulse pairs (50 fs single-pulse duration) of two different wavelengths (400 and 800 nm) is studied experimentally. Parallel polarized doublepulse sequences with a variable delay Delta t between -10 and +10 ps and between the individual fs-laser pulses were used to investigate the LIPSS periods versus Delta t. These two-color experiments reveal the importance of the ultrafast energy deposition to the silica surface by the first laser pulse for LIPSS formation. The second laser pulse subsequently reinforces the previously seeded spatial LIPSS frequencies. (C) 2013 AIP Publishing LLC.