Double-Scattering Approximation Theory of Enhanced Backscatterings of Light Produced from Aggregated Particles

We theoretically analyze the spatial anisotropy and polarization dependences of enhanced backscattering of light using a double-scattering approximation. The polarization of light is calculated in terms of the Jones vector and the scattering amplitude matrix. We discuss the cases where the individual scattering event is isotropic and governed by Rayleigh scattering for the media in which scatterers are homogeneously dispersed and aggregated. The spatial properties of the far-field intensity distribution can be demonstrated by asymptotic expansions in the region of the large backscattering angle. As a result, we theoretically reveal the polarization anisotropy of the decreasing variation in the far-field intensity distribution dependent on the fractal dimension, the azimuth in the backscattering angle, and the polarization state.