Laser-induced defects in fused silica by femtosecond IR irradiation

Photostructural defects resulting from exposure to intense near-infrared femtosecond radiation is studied in three $a\text{\ensuremath{-}}\mathrm{Si}{\mathrm{O}}_{2}$ glasses with different impurity levels. The photoinduced defects are studied by UV absorption spectroscopy and are correlated to the structural modifications in the glass matrix through Raman spectroscopy. Information in the dynamics of the defect generation is revealed by the small photon energy of IR femtosecond laser radiation.