THG IN DIELECTRICS USING LOW-ENERGY TIGHTLY-FOCUSED IR FEMTOSECOND LASER: THIRD-ORDER NONLINEARITY MEASUREMENTS AND THE EVOLUTION OF LASER-INDUCED PLASMA

The third-order nonlinearity chi((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.