Fundamental mechanisms of laser-induced damage in optical materials: understanding after 40 years of research

Abstract

Results of experimental and theoretical studies, carried out in the author's laboratory during past four decades, of fundamental mechanisms of laser induced damage (LID) to transparent solids are reviewed. Major features of LID experimentally observed in optical materials of different classes at various conditions (dependence of damage thresholds on radiation frequency, pulse width, temperature, etc.) are discussed. Theoretical models of both extrinsic (absorbing inclusion-initiated )and intrinsic (impact and multi-photon ionization) damage mechanisms are presented and their predictions for damage features (frequency and pulse-width dependence) are discussed. Peculiarities of LID in an ultrashort (ps-fs) laser pulse duration range are analysed . In this context a relative role of thermo-elastic stress-induced crack formation and ablation processes is considered. Experimentally observed features of LID are compared with theoretically predicted ones and conclusions are outlined on dominating LID mechanisms in real optical materials. Further directions in experimental and theoretical studies are discussed for investigating fundamental LID mechanisms in the ultra-short time domain.