Femtosecond laser pulse induced breakdown in dielectric thin films - art. no. 045117

Laser-induced breakdown of a high-quality mirror consisting of alternating lambda /4 layers of Ta2O5 and SiO2 and a single 500-nm thin film of Ta2O5 w ere studied with amplified and unamplified femtosecond pulses. Thr experime ntal data can be fitted with a model taking into account multiphoton absorp tion. impact ionization. and local intensity enhancements due to interferen ce effects in the films. Incubation effects are observed when the coatings are damaged with multiple pulses from a femtosecond oscillator. The results indicate that state of the art, high-quality thin films show a damage beha vior that is similar to bulk materials. Defects and impurities play a negli gible role.