Coherence theory of electromagnetic fields

Recent work on electromagnetic theory of partially coherent fields is reviewed. It is shown that traditional approach in the definition of the degree of coherence must be revised if partially polarized fields are examined. Coherence effects are examined both in the space-time and the space-frequency domain, in which the conditions for complete electromagnetic coherence are presented. Coherent-mode expansion in the space-frequency domain is recalled and then employed in the resonator analysis.