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The imaging processing technique was used for studying a laser beam nature that transmitted through films of PM-355. The thermal nonlinearity of PM-355 films was studied using a 635 nm cw diode laser at 15 mW as the source of excitation. Third order nonlinear optical properties of PM-355 films irradiated with α-particles at different times and pristine sample has been studied using Z-scan technique. The samples showed a negative and large nonlinear refractive index and reverse saturable absorption (RSA) with high values of the nonlinear absorption coefficient. The fluorescence spectra of PM-355 films were investigated at room temperature and wavelength range of 250–500 nm for a pristine film and in different times of exposure to α-particles. The broad peaks were between 350, 420 and 465 nm. All-optical switching property of PM-355 samples irradiated with α-particles at 20 min was also studied using the standard pump-probe technique.

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The nonlinear absorption and refraction indices for 2,3-Diaminopyridine solution were measured using open-and closed-aperture z-scan techniques, with continuous wave (cw) irradiation. Furthermore, diffraction rings pattern as a result of nonlinear refraction was observed. The effect of concentration, wavelength and laser intensity on the nonlinear absorption, nonlinear refraction and diffraction rings are studied experimentally. It is found that the nonlinear refraction and absorption indexes in order of 10 -8 cm 2 /W and10 -3 cm/W, respectively. We suggested an opportunity to form a new nonlinear-optical media for nonlinear optical application.