PECULIARITIES OF Z-SCAN TECHNIQUE IN LIQUIDS WITH THERMAL NONLINEARITY (STEADY-STATE REGIME)

Z-scan curves observed experimentally in steady state in liquids with thermal nonlinearity, and in particular in ethanol at 633 nm, differ r emarkably from those reported for pulsed regime of illumination in the se or in conventional Kerr-like nonlinear media. These differences are explained in framework of simple analytical analysis of Gaussian beam propagation through the thermal photoinduced lens. The results obtain ed explain some important experimental features (in particular peak-to -valley separation and flat wings of the Z-scan curve) and show that t he equations obtained earlier for Kerr like media are not applicable f or liquids with steady state thermal nonlinearity (in particular for e stimation of nonlinear parameters or for interpretation of experiments on spatial soliton propagation).