Abstract:We have reported the characteristics of a z-scan for the Poly(azaneylylidene-acylene) "DAZA" polymer as nonlinear medium with a large nonlinear phase shift using CW laser beam. It has been verified that the Fresnel diffraction model is applicable for analyses of z-scan measurements with DAZA polymer at high power. It was found that z-scan curves with peak-to-valley features appear as the applied light intensity increases in the case of a large nonlinear phase shift. The z-scan experiments were carried out of DAZA polymer by a CW laser to verify the theoretical calculations in the case of a large nonlinear phase shift model. Our results show good agreements between the experimental data and the proposed theoretical model.