THG in dielectrics using low-energy tightly-focused ir femtosecond laser: third-order nonlinearity measurements and the evolution of laser-induced plasma

Abstract

The third-order nonlinearity x(3) and other optical properties of LiF, CaF2, fused silica, and free standing polymeric thin film are studied using a diagnostic technique based on the third-harmonic generation of tightly-focused femtosecond Cr:forsterite laser radiation. Time-resolved measurements of the plasma evolution in the bulk of a fused silica sample are performed by a pump-probe technique using the fundamental and third-harmonic radiation as a probe. With the use of the pump-probe technique, two types of the relaxation processes are registered.