arXiv:1708.02011 · Physical Review A
Dipolar bright solitons and solitary vortices in a radial lattice
Chunqing Huang, Lin Lyu, Hao Huang, Zhaopin Chen, Shenhe Fu, Haishu Tan, Boris A. Malomed, Yongyao Li
Abstract
Stabilizing vortex solitons with high values of the topological charge $S$ is a challenging issue in optics, studies of Bose-Einstein condensates (BECs), and other fields. To develop an approach to the solution of this problem, we consider a two-dimensional dipolar BEC under the action of an axisymmetric radially periodic lattice potential, $V(r)\ensuremath{\sim}cos(2r+\ensuremath{\delta})$, with dipole moments polarized perpendicular to the system's plane, which gives rise to isotropic repulsive dipole-dipole interactions. Two radial lattices are considered, with $\ensuremath{\delta}=0$ and $\ensuremath{\pi}$, i.e., a potential maximum or minimum at $r=0$, respectively. Families of vortex gap soliton (GSs) with $S=1$ and $S\ensuremath{\ge}2$, the latter ones often being unstable in other settings, are completely stable in the present system (at least up to $S=11$), being trapped in different annular troughs of the radial potential. The vortex solitons with different $S$ may stably coexist in sufficiently far separated troughs. Fundamental GSs, with $S=0$, are found too. In the case of $\ensuremath{\delta}=0$, the fundamental solitons are ring-shaped modes, with a local minimum at $r=0.$ At $\ensuremath{\delta}=\ensuremath{\pi}$, they place a density peak at the center.