Nonlinear optical properties of gold nanoparticles dispersed in different optically transparent matrices

The nonlinear optical properties of gold nanoparticles dispersed in optically transparent matrices Al₂O₃, ZnO, and SiO₂ are investigated using the classical and off-axis techniques of the Z-scan method at a wavelength of 532 nm (radiation from a nanosecond Nd: YAG laser). The experimental data on the nonlinear refraction in composite materials are obtained. The nonlinear refractive indices and the light absorption coefficients are determined, and the real and imaginary parts of the third-order nonlinear susceptibility for the structures under investigation are calculated. It is demonstrated that, for the composite materials under consideration, the nonlinear properties of the medium under the chosen conditions of laser irradiation are predominantly determined by the Kerr effect and the contribution of this effect exceeds the contribution of the thermal lens.