Optical waveguiding by necklace and azimuthon beams in nonlinear media

Nonlinear necklace and azimuthon beams were experimentally generated in a self-focusing bulk photorefractive nonlinear medium (crystal SBN:60) using a frequency-doubled Nd:YVO₄ laser at 532 nm. The parallel optical waveguides induced by such a beam were probed by near-infrared signal beams emitted by a Ti:Sapphire laser. The quality and time stability of the guided sub-beams at the exit of the crystal were investigated. In view of the waveguides' ordering along a ring, the best matching probe beams were found to be singly or doubly charged optical vortex bright rings. The results indicate the feasibility of parallel all-optical guiding of optical signals at wavelengths, for which the nonlinear medium is not photosensitive.