Abstract

Optical vortex solitons have been studied previously in Kerr-type¹ and saturable² self-defocusing nonlinear systems. Here we report, for the first time we believe, on self-trapping of an optical vortex in both transverse dimensions resulting from two distinctly different nonlinear mechanisms: the bulk photovoltaic effect in an unbiased photovoltaic-photorefractive crystal, and the steady-state screening effect in a biased photorefractive crystal. In both cases, a singly charged vortex nested in a broad optical beam is trapped into a circular or an elliptical soliton-like structure.

© 1997 Optical Society of America