Factors that influence photon transport in dense random media

Photon localization is a phenomenon in which the photon diffusion coefficient is reduced or renormalised by constructive interference in random media exhibiting a high degree of multiple scattering. Factors that influence photon transport in such media have been experimentally investigated using extinction, time-resolved pulse transmission, and angular resolved coherent backscattering measurements. Scattering particle-particle correlations were found to increase the photon diffusion coefficient. Correlations introduced via the hard sphere Percus-Yevick radial distribution function successfully modified the independent scatterer result. Phase coherence of time-reversed or conjugate paths was broken by an external magnetic field resulting in reduction of the coherent backscattering enhancement. This reduction was explained by a magnetically induced form or shape birefringence. Surface reflectivity was found to increase the average photon path length leading to an erroneously small time-resolved diffusion coefficient and a larger coherent backscattering diffusion coefficient.