Generation of rotating multi-vortex laser beams

We study transverse dynamics of the optical field, generated in a single-frequency laser of moderate Fresnel number. The existence of steadily rotating vortex clusters generated spontaneously in laser with degenerate in frequency cavity is demonstrated numerically and experimentally in laser-like two-wave-mixing photorefractive oscillator with plane-mirror cavity and controlled aperture. The observed rotational dynamics of two-, three- and four-vortex clusters is explained within the framework of the general nonlinear pattern forming model.