Detecting the topological charge of partially coherent electromagnetic vortex beams through the orientation angle of polarization

Abstract By analysis of the orientation angle of polarization (OAoP) of a partially coherent electromagnetic Gaussian Schell-model vortex (EGSMV) beam, we find that the OAoP distribution is the shape of petal and demonstrate an implicit rule that the number of petals is equal to twice the magnitude of the topological charge of the partially coherent EGSMV beam. The sign of the topological charge is related to the rotation direction of the petals. This novel rule provides an effective method for detecting the orbital angular momentum of a partially coherent electromagnetic vortex beam in applications such as free space optical communication and quantum information.