A Novel Analysis Method of Electromagnetic Vortex Wave Based on Modified Dynamic Mode Decomposition

Recently, electromagnetic (EM) beams with the orbital angular momentum (OAM) have been explored for multiplexing in communication systems. Each OAM mode is encoded with data and can be identified by the OAM index, namely the topological charge. So far, the amplitude of OAM mode is gaining more attention for its application as another modulation format. Therefore, it is of great importance to accurately extract both the OAM index and corresponding amplitude. In this paper, we propose a modified dynamic mode decomposition (DMD) approach for the analysis of OAM modes. It is shown that not only topological charges but also high-resolution amplitude patterns of both single OAM mode and composite OAM modes can be obtained. The proposed approach provides an effective tool for the demultiplexing of OAM-carrying beams, especially in the case when the amplitude information is required.