Localized pulsed laser interaction with submicronic gold particles embedded in silica: a method for investigating laser damage initiation.

Laser damage phenomena in fused silica are currently under study because of numerous related high power laser applications. Nanosized defects are believed to be responsible for some laser damage initiation. In order to predict and to quantify this initiation process, engineered submicronic gold defects were embedded in silica. The study of these samples by localized pulsed irradiation of isolated gold particles coupled with Nomarski, atomic force and photothermal microscope observations permits us to discriminate between two distinct stages of material modification: one detectable at the surface and the second in the neighbourhood of the embedded particle. Comparison between the observations and simulations results in good agreement if we assume that inclusion melting initiates the damage.