Laser-induced damage threshold at different wavelengths of Ta2O5 films annealed over a wide temperature range

The laser-induced damage of Ta2O5 films annealed at a wide range of temperature (473-1273 K) at the laser wavelengths of 1064 and 355 nm was investigated. The relations between microstructure, optical properties, chemical composition, absorption and laser-induced damage threshold (LIDT) were studied. The dependence of a damage mechanism on laser wavelengths was discussed. It was found that the LIDT either at 1064 or 355 nm first increased and then decreased with increase of annealing temperature. The LIDT at 1064 nm was influenced by the substoichiometric defects, structural defects and thermal diffusion, whereas at 355 nm it was affected mainly by the intrinsic absorption and structural defects. Both the maximum LIDT at the two wavelengths were obtained at the annealing temperature of 873 K, which could be attributed to the lowest defect density in films.