Topological Charge Identification of Vortex Beams Through Optical Correlation

Recently optical beams containing orbital angular momentum have gained considerable attention due to their wide range of uses. In all the applications, accurate determination of the magnitude and sign of the topological charge (TC) is very important. Different techniques for determining the vortex beam's TC have been reported such as interferometric, diffractive, and machine learning based methods. In this letter, we demonstrate a novel technique to identify the TC of a vortex beam using the optical correlation method where a maximum average correlation height filter has been used. Unlike conventional methods, the proposed method enables instant identification of TC without manually counting the number of fringes and requires lesser datasets with simple architecture as compared to the machine learning-based method. The proposed idea is verified through both numerical simulation and experimental results with the help of fork-shaped interferometry.