Random Walk of Polarized Light in Turbid Media

Abstract

We study the propagation of polarized light in turbid media as a random walk of vector photons. Both propagation and polarization directions of light are found to isotropize, following a power law of the number of scattering events. The characteristic length scale governing light isotropization and linear depolarization, the isotropization length $l_p$, is derived using the exact Mie scattering for spherical particles. A simple relation $l_p/l_t\simeq 2.8-2.5g$ is obtained for Rayleigh-Gans scatterers where $l_t$ is the transport mean free path and $g$ is the mean cosine of scattering angles.