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Effect of plasma treatment on the nonlinear optical properties of red lake doped commercial polyvinyl chloride (PVC) film is studied employing different techniques. PVC films were exposed to low pressure plasma from 5 to 15 min. Nonlinearity measurement was performed using the second harmonic of a continuous Nd-YAG laser beam at 532 nm wavelength and 50 mW power. The optical limiting behavior of samples was investigated by measuring their transmission at different beam intensities. For all pristine and plasma treated samples optical limiting started at laser beam power of 12 mW. The nonlinear refractive index and nonlinear absorption coefficient of plasma treated samples were measured using Z-scan method. Second order nonlinear refractive index of samples was measured to be in the range of $$10^{-8}\,\hbox {cm}^2/\hbox {W}$$ which was decreased after plasma treatment. Experimental results show that real and imaginary parts of nonlinear susceptibility are strongly influenced by plasma treatment. [ABSTRACT FROM AUTHOR]

The effect of thickness on the nonlinear optical properties of Au nanoparticles which produced by laser ablation of high purity gold bulk in distilled water were investigated by employing different optical techniques. Experiments were performed on the 0.3, 0.6, and 1 mm thickness cells of Au nanoparticles-fluid. The effect of nonlinear refractive index of samples on the laser beam broadening was observed. The optical limiting behavior of samples is investigated by measuring the transmitted intensity of the laser beam through the samples. The third order nonlinearity of Au nanoparticles-fluid was measured by using Z-scan data. Results show a positive second order refractive index and absorption coefficient for Au nanoparticles-fluid that are increased in due of increasing the thickness of the cells. The magnitudes of both real and imaginary parts of third order susceptibility of samples are increased by increasing the thickness. [ABSTRACT FROM AUTHOR]