ABSTRACT
The extension of the second-order coherence theory from scalar to electromagnetic beams has been made in the early 1990s. It was first shown by James via a numerical example that the state of coherence of the source generating a stochastic beam may influence its degree of polarization when the beam propagates in free space. Later the beam coherence-polarization matrix was introduced by Gori, which can be regarded as a generalization of the mutual coherence function of a scalar beam-like field to the electromagnetic domain. Angular spectrum decomposition electromagnetic fields both deterministic and random, is another important mathematical representation that substantially simplifies the analysis of the properties of sources and fields they generate. It has played the major role in radiometry, scattering theory and wave propagation in random media. The concept of quasi-homogeneity was developed a long time ago in connection with locally stationary random processes and scattering media.
