We consider the three-dimensional (3D) Gross-Pitaevskii/nonlinear Schrodinger equation with a quasi-2D square-lattice potential, which corresponds to the optical lattice trapping a self-attractive Bose-Einstein condensate (BEC), or to a photonic-crystal fiber, in terms of nonlinear optics. Stable 3D solitons, with embedded vorticity S = 1 and 2, are found by means of the variational approximation and in a numerical form. They are built, basically, as sets of four fundamental solitons forming a rhombus, with phase shifts πS/2 between adjacent sites, and an empty site in the middle. The results provide for the first examples of stable 3D vortex solitons ("spinning light bullets", in terms of optics) with S > 1, and the first ever examples of vortex solitons (with any S ≠ 0) supported by a lattice in the 3D space. Typical scenarios of instability development (collapse or decay) of unstable localized vortices are identified too.

Date Published: 1 August 2007
PDF: 8 pages
Proc. SPIE 6785, ROMOPTO 2006: Eighth Conference on Optics, 678510 (1 August 2007); doi: 10.1117/12.757861

Published in SPIE Proceedings Vol. 6785:
ROMOPTO 2006: Eighth Conference on Optics
Valentin I. Vlad, Editor(s)