Interstitial O2 and Si-H defects produced in fused silica during laser-induced damage

Abstract

Fused silica irradiated with 6.8 ns 355 nm laser pulses is studied by micro-Raman scattering spectroscopy. Results show that, for laser fluences above the laser-induced breakdown threshold (Fth ~3.9 J/cm2), irradiation results in the formation of four laser-induced defect-related Raman bands centered at 1363, 1557, 1605.9 and 2330 cm−1. Bands centered on 1363, 1557 and 2330 cm−1 are attributed to Si = O, interstitial O2 and Si-H bond. However, defects giving rise to a broad band at 1605.9 cm−1 are unknown. Based on these results, we discuss physical processes occurring during the laser-induced fused silica breakdown, leading to the formation of Si-H bond and interstitial O2 and the fracture of fused silica.