Orbital angular momentum of Laguerre-Gaussian beams with non-zero radial index at limited aperture size

Abstract

The study of orbital angular momentum (OAM) calculation and measurement of complex radial structure beams with limited receiving aperture size is of practical significance. In this paper, taking the Laguerre-Gaussian beam with non-zero radial index as an example, we give the calculation method of its OAM at limited aperture size and design an experiment. We theoretically and experimentally demonstrate the strong correlation between OAM and radial number and we believe that the calculation method can be extended to all local OAM calculations with complex radial structure beams.