Optical properties of small particles and composite materials

Optical properties of submicron size particles and other nanostructures are determined by two different physical effects. The electric field penetration and distribution has a strong frequency dependence due to Mie type resonances. Secondly, quantum size effects influence the spectra and interactions of various excitations like electrons, excitons and phonons. Interplay of these two types of effects gives rise to a variety of linear and nonlinear optical phenomena which have been investigated a great deal during the last few years. The materials of interest are small particles and other nanostructures of semiconductors and metals. The nonlinear optical phenomena such as optical phase conjugation by degenerate four wave mixing, optical Kerr effect, saturation of absorption and optical bistability have been investigated in these materials. A brief overview of the available experimental information and our present theoretical understanding will be presented