Intensity fluctuations and the degree of cross-polarization in stochastic electromagnetic beams

Abstract

An expression is derived for the correlation between intensity fluctuations at pairs of points in a stochastic electromagnetic beam, obeying Gaussian statistics. The new formula, which is of particular interest for the theory of the Hanbury Brown?Twiss effect, applies to beams of any state of coherence and state of polarization. It contains a new 'two-point' degree of polarization whose presence indicates that, in general, the knowledge of the degree of coherence and of the usual degree of polarization are not adequate for determining the correlation between intensity fluctuations.