SEQUENTIAL FORMATION OF MULTIPLE DARK PHOTOREFRACTIVE SPATIAL SOLITONS - EXPERIMENTS AND THEORY

Steady-state dark photorefractive spatial screening solitons are obser ved in an odd- or even-number sequence when a laser beam that contains a dark stripe generated from a phase or amplitude discontinuity in th e center of the beam is launched into a biased bulk strontium barium n iobate crystal. If the initial width of the dark stripe is small, only a fundamental soliton or a Y-junction soliton is generated, correspon ding to the lowest order in the odd- or even-number soliton sequence. As the initial width and the bias field are increased, we observe a pr ogressive transition from a lower-order soliton to a sequence of highe r-order multiple solitons. We show that these dark solitons induce sta ble waveguides that can guide an intense beam of a different wavelengt h into multiple channels. Comparisons between experiments and theory o n multiple dark spatial solitons are presented and shown to be in good agreement. (C) 1997 Optical Society of America.