Double-slit experiment with multiple vortex beams

The orbital angular momentum (OAM) of a vortex beam has already found significant potential applications in both quantum and classical communication systems. In this study, a realization of a double-slit experiment using a Sagnac interferometer is conducted for the detection and discrimination of vortex beams. Based on the advantages of convenient and adjustable double-slit parameters of our device, we detected multiple vortex beams carrying different OAM modes and superpositions of OAM modes under laser and single-photon illumination. We also analyzed the influence of the slit parameters on the interference pattern of the vortex beams. The results show that by comparing the differences in these interference patterns, we can achieve the measurement of topological charge and complete distinction of OAM states carried by the vortex beams. Our study contributes to coding research on laser and quantum communication.