Theorems on complete electromagnetic coherence in the space-time domain

Making use of a recently introduced degree of coherence of random electromagnetic fields, we show that some well-known results on second-order scalar coherence theory in the space-time domain hold within the electromagnetic context as well. In particular, we prove that for statistically stationary electromagnetic waves the following three properties are equivalent: (i) the field is completely coherent in the space-time domain, (ii) the field is monochromatic, and (iii) the electric mutual coherence tensor factors in the two spatial variables and is periodic in the time difference. (C) 2004 Elsevier B.V. All rights reserved.