title: Theory of partially coherent electromagnetic fields in the space-frequency domain.
abstract: We construct the coherent-mode representation for fluctuating, statistically stationary electromagnetic fields. The modes are shown to be spatially fully coherent in the sense of a recently introduced spectral degree of electromagnetic coherence. We also prove that the electric cross-spectral density tensor can be rigorously expressed as a correlation tensor averaged over an appropriate ensemble of strictly monochromatic vectorial wave functions. The formalism is demonstrated for partially polarized, partially coherent Gaussian Schell-model beams, but the theory applies to arbitrary random electromagnetic fields and can find applications in radiation and propagation and in inverse problems.
authors.affiliation: University of Joensuu, Department of Physics, P.O. Box 111, FI-80101 Joensuu, Finland. jani.tervo@joensuu.fi
authors.forename: Jani
authors.initials: J
authors.lastname: Tervo
authors.forename: Tero
authors.initials: T
authors.lastname: Setälä
authors.forename: Ari T
authors.initials: AT
authors.lastname: Friberg