Effect of nonlinear phase shift on symmetry of Z-scan curves

Based on the simulated results of normalized Z-scan transmittance by using ABCD formalism and q parameter, analysis on the variational characteristics of Z-scan curves with nonlinear phase shifts proves that the asymmetry of the curve is more greatly affected by nonlinear refractive phase distortion than by nonlinear absorptive one, and that the Z-scan curves of a certain media with strong saturated absorption and weak self-focusing third-order nonlinearity will not hold the dispersive-like characteristics any more. With the absorptive nonlinear phase shift of 0.9 and coupling factor of -10 in the transmittance expression, the fitting with the experimental data for ZnCdSe-ZnSe(MQWs) of 1 μm thickness conducted with 532 nm TEM00 brought in almost the same results of third-order nonlinear