Fatigue laser-induced damage in transparent materials

We discuss the damage in transparent dielectrics produced by a train of laser pulses, each of which is less intensive than it is needed to cause the macroscopic breakdown. The problem under consideration includes both engineering and fundamental aspects. The practical interest is corresponded to the problem of long-term operation of optical elements in high-power laser systems. The main task of the theoretical analysis is to estimate the relative contribution of impurity-related and intrinsic processes into the phenomenon of `fatigueʹ (cumulative) damage. The experimental data concerning the subthreshold laser-induced damage are reviewed here, together with the proposed to date multi-shot damage mechanisms, which are described in the main features.