Three-dimensional vortex solitons in self-defocusing media

The existence and robustness of dark vortices in bi-dispersive and/or normally dispersive self-defocusing nonlinear media is demonstrated. The underlying equation is the bi-dispersive three-dimensional nonlinear Schrodinger equation. These solutions can be considered as extensions of two-dimensional dark vortex solitons which, along the third dimension, remain localized due to the interplay between diffraction and nonlinearity. Such vortex solitons can be observed in optical media with normal dispersion, normal diffraction, and defocusing nonlinearity.