Periodic propagation properties and radiation forces of focusing off-axis hollow vortex Gaussian beams in a harmonic potential

Gengxin Chen, Jintao Xie, Dongsen Cai, Qiliang Sun, Dongmei Deng

Obtaining the analytical expression of focusing off-axis hollow vortex Gaussian (HVG) beams by solving the (2 + 1) dimensionless linear Schrödinger-like equation, we perform the propagation path, the intensity and phase distributions, the center of mass, the peak intensity and the beam width with different potential widths , different hollow orders , different topological charges , different off-axis coordinates (). In general, the off-axis HVG beams are swirled counterclockwise and periodically focus during the propagation. The topological charge separates the focusing center but the hollow order concentrates the focusing area. Moreover, the off-axis coordinate () significantly increases the focusing intensity and the potential width can also increase the focusing frequency during the propagation. Interestingly, the influences of the hollow order , the topological charge and off-axis coordinate () are the same on the peak intensity, which are different with the beam width. Furthermore, we also discuss the Poynting vector, angular momentum and radiation forces. In terms of the radiation forces, we can easily explore the position trapping particles stably regardless of the off-axis coordinate () selection.

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