Anomalous optical nonlinearity of dielectric nanodispersions

Abstract

We present the results of studying the nonlinear optical response of nanodispersions of semiconductor and dielectric nanoparticles of spherical, spheroidal and flake shape, suspended in polar and nonpolar dielectric matrices (water, isopropanol, polymethylsiloxane and transformer oil) by means of -scanning in the field of low-intensity visible laser radiation. It is found that, unlike semiconductor nanoparticles and particles of spherical shape, flake-shaped and nanoparticles suspended in nonpolar matrices exhibit nonlinear optical response within the intensity interval from to that vanishes at higher intensities. The diagrams of energy states of the optical electrons in nanoparticles that allow explanation of differences in the nonlinear-optical properties of nanodispersions are proposed. Good agreement between the experimental and theoretical dependences of nonlinear refractive indices and absorption coefficients on the intensity of radiation is observed.