Accurate determination of nonlinear refraction and nonlinear absorption by a single Z-scan method

We present a theoretical model of optical beam propagation in a nonlinear medium for determining the nonlinear refraction and nonlinear absorption accurately and simultaneously by a single Z-scan method. The model is based on the Gaussian decomposition method and symmetric analysis. In principle, accurate nonlinear refraction and nonlinear absorption can be obtained simultaneously by exact experimental data, no matter how much they are. The treatment procedure of Z-scan experimental data is demonstrated.