What time-resolved measurements tell us about femtosecond laser damage?

Abstract

Time-resolved investigations of laser-matter interaction processes in dielectric coatings and bulk silica leading to laserinduced damage were performed with high temporal and spatial resolution. Distinct excitation geometries were used to study different aspects of laser matter interaction. Samples were irradiated at the pump fluence levels below and above their single shot laser-induced damage thresholds. The obtained results provide new insights about the sequence of interdependent processes. The fundamental differences between the so called 1-on-1 and S-on-1 damage morphologies are observed and discussed. New data of numerical simulations revealing the nonlinear properties of optical thin films are presented. Increased visibility in time resolved damage detection as well as observation of coherent oscillations in measured signals are introduced and discussed.