Computer simulation studies of the speckle correlations of light scattered from a random array of dielectric spheres of random radii or dielectric constants

Abstract

Computer simulation studies are presented for the speckle correlation function for light elastically scattered by a spatially random array of dielectric spheres in three-dimensional space within the context of a scalar wave theory. In addition to the spatial randomness, the spheres in our model are taken to have a statistical distribution of radii and dielectric constants. Results are presented for cases in which the radii of the spheres are much less than the wavelength of the light so that the scattering from the individual spheres is approximately $s$---wave in nature, and the volume filling fraction of the spheres is small. In a first set of simulations a homogeneously random system is considered. A second set of simulations treats a random system that is spatially periodic on average. In both cases, the effects of a statistical distribution of sphere radii and dielectric constants are determined and compared with results presented in Phys. Rev. B 64, 165204 (2001) for a spatially random array of identical spheres. In a final series of simulations the spheres of the array are taken, in addition to the spatial randomness, to have a Kerr nonlinear dielectric constant. Changes in the speckle correlation functions are determined as a function of the Kerr parameter and incident field intensities. The scalar wave theory has been used recently in the treatment of scattering from random media in which phase interference effects are of interest, e.g., Anderson localization phenomena, speckle correlations, and effects related to universal conductance fluctuations. The scalar field also models acoustical excitations and scalar wave electron propagation in random media.