Multi-component vector solitons in photorefractive crystals

We study the existence and stability of multi-component spatial optical solitons in anisotropic nonlocal photorefractive media. For the case of three components, we find numerically the whole family of composite solitons with two perpendicular dipole components, and show their stability for a wide range of parameters. We confirm our theoretical results by an experimental observation of these novel types of composite optical solitons in a photorefractive strontium barium niobate crystal. 2002 Elsevier Science B.V. All rights reserved. PACS: 42.65.Tg; 05.45.Yv; 42.65.Hw Recently, there has been growing interest in the study of composite (or vector) optical solitons [1,2]. Such solitons are optical beams that consist of several components that self-trap together when propagating in a nonlinear medium. Essential for the formation of this kind of vector soliton is the absence of coherent wave-mixing effects, i.e., the interference of beams must be suppressed during their nonlinearity-mediated interaction. This has first been suggested [3,4] and realized [5] with the beams carrying orthogonal states of polarization. Later, this concept has been generalized to include all kinds of optical self-trapped beams that are mutually incoherent with each constituent beam being a corresponding component of a generalized multi-dimensional ‘‘vector beam’’ [6]. As is well accepted, the fundamental optical soliton induces an optical waveguide in a nonlinear medium and propagates self-consistently as its fundamental mode [7]. In the same way, components of the composite (vector) soliton represent various (higher) modes of the self-induced wave15 August 2002 Optics Communications 209 (2002) 501–506 www.elsevier.com/locate/optcom Corresponding author. Tel.: +61-261-253-752; fax: +61-261250-029. E-mail address: [email protected] (W. Kroli-