Multiple scattering of light in a resonant medium

We investigate some signatures of multiple scattering of light in a vapor of laser-cooled rubidium atoms. This sample presents several unusual properties when compared to classical samples i.e. white paper or suspensions of dielectric particles: a very strong resonance, an internal structure of the atomic scatterer, and a spherically symmetric geometry with a quasi-Gaussian density profile, We study how the light frequency modifies static quantities such as the coherent transmission, the diffuse transmission and reflection, and the coherent backscattering cone. The experimental data are compared to a Monte Carlo simulation including all experimental parameters. (C) 2004 Elsevier B.V. All rights reserved.