Average characteristics of partially coherent electromagnetic beams

Average characteristics of partially coherent electromagnetic beams are tre ated with the paraxial approximation. Azimuthally or radially polarized, az imuthally symmetric beams and linearly polarized dipolar beams are used as examples. The change in the mean squared width of the beam from its value a t the location of the beam waist is found to be proportional to the square of the distance in the propagation direction. The proportionality constant is obtained in terms of the cross-spectral density as well as its spatial s pectrum. The use of the cross-spectral density has advantages over the use of its spatial spectrum. (C) 2000 Optical Society of America [S0740-3232(00 )01504-0] OCIS codes: 030.1670, 090.1970, 260.1960.