  Spatial field correlation functions represent a key quantity for the
description of mesoscopic phenomena in disordered media and the optical
characterization of complex materials. Yet many aspects related to the vector
nature of light waves have not been investigated so far. We study theoretically
the polarization and coherence properties of electromagnetic waves produced by
a dipole source in a three-dimensional uncorrelated disordered medium. The
spatial field correlation matrix is calculated analytically using a multiple
scattering theory for polarized light. This allows us to provide a formal
description of the light depolarization process in terms of "polarization
eigenchannels" and to derive analytical formulas for the spatial coherence of
multiply-scattered light.
