On the Damage Behavior of Dielectric Films When Illuminated with Multiple Femtosecond Laser Pulses

Abstract

The physical effects reducing the damage threshold of dielectric films when exposed to multiple femtosecond pulses are investigated. The measured tempe rature increase of a Ta2 O5 film scales exponentially with the pulse fluence. A polarized luminescence signal is observed that depends quadratically on the pulse fluence and is attributed to two- photon excitation of self-trapped excitons that form after band-to-band excitation.