Spatial coherence of azimuthally symmetric Gaussian electromagnetic beams

The spatial coherence properties of azimuthally symmetric electromagnetic b eams launched by planar Gaussian sources are investigated. The intensity di stribution and the coherence properties of the source do not vary in the az imuthal direction. A procedure is postulated for obtaining the root mean sq uared coherence length as a function of position in a plane transverse to t he propagation direction. The variation of the root mean squared coherence length with the position in a transverse plane as well as along the propaga tion direction is treated. The dependence of these variations on the source coherence parameter relative to the beam waist at the source plane is disc ussed. 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 a zimuthal direction although cylindrical symmetry is preserved with respect to the variation of the location of the point in the azimuthal direction. ( C) 2000 American Institute of Physics. [S0021-8979(01)03401-6].