Propagation properties of off axial partially coherent vortex beam

The propagation of off axial partially coherent vortex beam (PCVB) has been investigated. The analytical expression for the average intensity and position of the beam centroid are derived, based on which the average intensity distribution of off axial PCVB is numerically studied. It is found that the intensity distribution very much relies on the correlation length. Even so there always exists a symmetric axis, which tends to become vertical during propagation. Besides, it is interesting to find that the transverse coordinates of the centroid are proportionally correlated by the ratio of propagation distance to Rayleigh distance. This research is beneficial to free space communication of partially coherent vortex beam.