Vortex grating-encrypted orbital angular momentum multiplexed holography

The orbital angular momentum (OAM) owning to the special superiority with the inherent orthogonality, has been identified as an information carrier. In this paper, we proposed a simple and direct method for measurement the OAM of the vortex beam by using vortex grating encrypted OAM holography. When the detected beam illuminates the designed OAM holography, the topological charge (TC)value will be directly read from the reconstruct results which appear as a series of solid Gaussian or ring spots at the output surface of the system. Thus, according to the reconstruct results, we can not only easily detect the modulus but also the sign of the incident beam. Furthermore, it can simultaneously identify OAM modes of multiple incident vortex beams. It's demonstrated that the proposed method is an efficient and flexible method.