Effect of the oxygen non-stoichiometry on the damage threshold of the SiO_2-δ system optical coatings

Abstract

The results of the coulometric study of the processes of oxygen sorption–desorption in optical coatings (OCs) of the SiO_{2- δ} system deposited by the electron-beam sputtering technique are presented. The character of structural transformations occurring when the coatings under-go polythermal annealing within the temperature range from 200 to 1000°C and at oxygen partial pressures p _O2=10²–10⁵ Pa has been established. It has been ascertained that the intensity of photoluminescence of the OCs and shift of the absorption edge depends on the annealing condition within the temperature range from 400 to 550°C in the dehydrated oxygen atmosphere that is caused by the coagulation of silicon atoms with their subsequent oxidization. The dependence of the optical damage thresholds of the SiO_{2- δ} on structural defects has been studied.