Effect of electric field distribution on the laser damage probability curves of multilayer coatings

Abstract

The effect of electric field distribution on the laser damage probability curves of multilayer coatings is investigated. The interpretation of laser damage probability curves uses a statistical model, where shapes and slopes of the curves are related to the spot size and to the densities of nanodefects that are responsible for damage and where each kind of precursors is characterized by its damage threshold. This statistical model is improved by considering value and shape of electric field in each layer of the coating. Typical multilayer coating constituted by alternate materials of high and low index are considered. For each kind of nanoprecursors and for each fluence, the value of electric field which leads to damage is calculated. This relative threshold value permits to know with accuracy the ratio of the coating thickness where the irradiation fluence is greater than the nanoprecursor threshold and to finally estimate the appropriate laser damage probability curves.