Controllable splitting and bidirectional rotating of optical vortices due to cross phase

Abstract

We discussed evolution characteristics of optical vortices with the cross phase in free space and found that both splitting and rotating can occur for vortices with circular symmetry due to cross phase. The rotation is bidirectional and the rotational direction will reverse at some certain distance. The physical mechanism behind the splitting and rotating of vortices is considered to be the effective anisotropic diffraction, which results from the cross phase. We also investigated the dynamics of superimposed pattern with two astigmatic vortices of opposite cross phase. The rotating of vortices always happens, however, the splitting only occurs for nonzero net cross phase coefficient. The results in the paper provide us with a theoretical method to control the dynamics of vortices by adjusting the cross phase, then may find potential applications in the field of optical tweezers.