Simulation of Internal Stress Waves Generated by Laser-Induced Damage in Multilayer Dielectric Gratings

Multilayer dielectric (MLD) gratings used in ultrahigh-intensity laser systems often exhibit a laser-induced damage performance below that of their constituent materials. Reduced performance may arise from fabrication- and/or design-related issues. Finite element models were developed to simulate stress waves in MLD grating structures generated by laser-induced damage events. The models investigate the effects of geometric and material parameters on how stress waves contribute to amplifying material inhomogeneities, thereby reducing the overall damage performance: closer impedance matching of the layer materials reduces maximum interface stresses by ~20% to 30%; increasing sole thickness from 50 nm to 500 nm reduces maximum interface stresses by ~50%.