Diffraction characteristics of the azimuthal Bessel-Gauss beam

We examine the free-space propagation characteristics of an azimuthally polarized, circularly symmetric beam, such as that emitted by a concentric-circle-grating surface-emitting laser. We begin with the appropriate scalar wave equation and then find the azimuthal Bessel-Gauss beam solution, using both a Cartesian decomposition method and an angular spectrum representation. We find a general azimuthal diffraction integral for circularly symmetric disturbances and examine two special cases, a thin lens and a circular aperture; the azimuthally polarized beam remains well behaved in both cases. Plots of radial field profiles and longitudinal beam-waist evolution are presented. (C) 1996 Optical Society of America