Characterizing the temporal rotation and radial twist of the interference pattern of vortex beams

Abstract

We experimentally and theoretically characterize the temporal rotation and radial twist of the interference pattern of a vortex beam with its conjugate copy. To quantitatively study the temporal rotation and radial twist, we controllably modify the conjugate beam to obtain a frequency or wavefront curvature difference using a movable Mach–Zehnder interferometer. The effects of the physical parameters (i.e., the topological charge, frequency difference and wavefront curvature difference of the vortex beams) on the temporal rotation as well as radial twist are systematically explored. We further measure two parameters, the rotation velocity Ω and twist coefficient α, respectively, to characterize the degree of the temporal rotation and radial twist of the interference pattern. The theory of the interference model on vortex beams has good agreement with the experimental results. This work is helpful for study on the detailed structure of the interference pattern and manipulation of matter with superimposed vortex beams.