Optical Interference and Self-Scattering Effect On Laser Ablation of Thin Silicon Films

Abstract

We report measurement of the ablation depth and self-reflectivity from thin silicon films illuminated by a single tightly focused femtosecond laser pulse. We show the dependence of ablation depth on incident laser pulse fluence can be modeled with a transfer-matrix method, taking into account transient reflectivity and light propagation in a stratified medium. We find optical interference effects in laser ablation of thin films are of crucial importance. Furthermore, We present the evidence of self-scattering effects due to the buildup of a three dimensional submicron sized plasma in the focal region.