Identification of both orbital angular momentum and radial mode based on multiplexing holography

Abstract

In recent years, the azimuthal mode, also known as orbital angular momentum (OAM), and the radial mode of Laguerre Gaussian (LG) beams have been applied in many disparate areas of physics. Identification of these modes is a basic technique for these applications. Although there are many recognition methods, each has its own problems. Either it can only be used to distinguish OAM modes or radial modes, or the number of modes that can be distinguished is too small, or the operation is too complex. So, a great challenge is to design a method that is not only simple, but also applicable to the identification of both OAM and radial modes with high dimension. Here, by introducing strong mode selectivity, we propose a convenient method for the identification of OAM and radial modes based on multiplexing holography. In our method, only a single hologram is needed. Experiments on the identification of 100 OAM modes (l = −50, −49, …, +49, +50) have been carried out to demonstrate the feasibility of our design. Additionally, our method is also applicable for the identification of radial modes, and then to the identification of LG modes. In experiment, we have realized the identification of 8 radial modes (p = 1, 2, 3, …, 8) and 120 LG modes (p = 1, 3, 5, and l = −20, −19, …, +20). Our method should have important applications in high-capacity optical communication based on OAM modes, radial modes, or LG modes.