Spatial coherence of azimuthally symmetric Gaussian electromagnetic beams

Abstract

The spatial coherence properties of azimuthally symmetric electromagnetic beams launched by planar Gaussian sources are investigated. The intensity distribution and the coherence properties of the source do not vary in the azimuthal direction. A procedure is postulated for obtaining the root mean squared coherence length as a function of position in a plane transverse to the propagation direction. The variation of the root mean squared coherence length with the position in a transverse plane as well as along the propagation direction is treated. The dependence of these variations on the source coherence parameter relative to the beam waist at the source plane is discussed. On propagation, the root mean squared coherence length at any point in a transverse plane other than on the beam axis is found to vary in the azimuthal direction although cylindrical symmetry is preserved with respect to the variation of the location of the point in the azimuthal direction.