Thermal self-interaction of annular laser beams in a moving medium

An investigation was made of steady-state propagation of laser beams which had an intensity dip on the axis (annular beams) on entering (z = 0) a defocusing medium. The transverse structure of the beam was calculated and studied experimentally for various distances z and for various relative widths of the annulus. The z-dependences of the maximum intensity and the beam displacement were found. The results obtained were compared with those reported for Gaussian beams.