Abstract

Steady-state dark photorefractive screening-solitons, as predicted recently,¹ are observed when a laser beam containing a dark notch propagates through a bulk strontium barium niobate crystal biased by an electric field. The photorefractive dark solitons induce waveguides in the bulk of a photorefractive crystal that guide other beams. We use these soliton- induced waveguides to monitor the shape-preserving behavior of the dark soliton. A proper input beam at an appropriate external field can also generate Y junctions and Y-junction waveguides, as observed for Kerr-type solitons in slab waveguides.² We further confirm the shape preserving nature of dark solitons and Y-junctions by measuring the soliton beam-profile as it propagates throughout a specially cut (wedged) crystal.

© 1996 Optical Society of America