Effect of source anisotropy on the intensity correlations of stochastic electromagnetic beams in free space communications.

Correlations between stochastic electromagnetic beams' intensity variations which are produced by sources with anisotropic crossspectral density matrices are explored. Recently introduced spectral degree of cross-polarization, spectral degree of coherence, and the intensity fluctuations of electromagnetic sources are analyzed upon propagation by considering the source as an anisotropic beam. An analytical formula is given for the cross-spectral density matrix of an anisotropic electromagnetic Gaussian Schell beam moving across free space and extended to longitudinal and transverse directions. The analysis shows that the cross-polarization of two beams having same source parameters might increase or decrease on propagation depending on the anisotropy ratio α. Numerical results are presented to show that the beam anisotropy might be one of the convenient methods for modeling partially coherent sources. [ABSTRACT FROM AUTHOR]