Measurement of orbital angular momentum of light by polygon apertures

Abstract

We demonstrate measurement of orbital angular momentum (OAM) of light based on the Fraunhofer diffraction pattern (FDP) formed by traversing the light through regular polygon apertures. We simulate Laguerre-Gaussian (LG) beams with different topological charge l values, in order to obtain beams with different OAM lħ values. The FDPs produced using various polygon apertures are unique, thus can also be used to quantify the OAM of LG beams. We found that LG beams with higher l values can be determined by using polygon apertures that have relatively higher number of sides. We also showed that the relative polarities of l can only be measured using apertures that have odd number of line segments since these apertures can break the quadrant symmetry in the pattern.