离轴涡旋光束的传输特性

Based on the Fresnel diffraction integral and Fourier transform, the analytical expression for the propagation of off-axis elliptical vortex beams in free space is derived, which is used to study the intensity distribution and propagation of phase singularity by numerical simulation. The results show that the intensity distributions of beams change significantly while propagating. Position and number of phase singularities are dependent on the vortex position at the source plane, propagation distance and topological charge number. This research is useful for a deep understanding of the propagation of off-axis phase singularity, and provides guidance for the beam aligning. ?