离轴参量及传输距离对离轴涡旋光束传输特性的影响

he analytical expression for the propagation of off-axis vortex beams with topological charge ±1 through a single slit diffraction is derived based on the Fresnel diffraction integral, which is used to study the propagation of central phase singularity of off-axis vortex beams by using Mathematica software to numerical simulation. The simulation results show that the off-axis vortex beam passing through a single slit diffraction, the spatial distribution of phase singularities depends on propagation distance, the half-width of a single slit and off-axis parameter. Then, we study the anisotropic elliptical vortex beams. The analytical expression for the propagation of off-axis elliptical vortex beams with different topological charges in free space is derived, which is used to study the intensity distribution and propagation of phase singularity of off-axis elliptical vortex beams in detail by using Mathematica software to numerical simulation. The results show that in the case of off-axis the intensity distributions of beams will change significantly while propagation. And the position of phase singularity is always changes. The spatial distribution of phase singularities depends on propagation distance, off-axis parameter and the ratio of minor axis to major axis of ellipse. There are some different changes for different topological charges.