Improve The Capacity Of Data Transmission In Orbital Angular Momentum Multiplexing By Adjusting Link Structure

Optical vortex is a structured beam with a spiral phase wavefront. Different orbital angular momentums (OAM) are orthogonal to each other and multiplexed together without crosstalk. Vortex optical communication (VOC) can obtain good bandwidth and channel number. In this paper, we creatively exchanged the order of the spatial light modulator (SLM) and the optical switch, the communication link from "Vortex after Modulation (VAM)" to "Vortex Modulation (VM)", which constitutes a new link structure. Compared with the VAM communication link, the VM link has the advantages of higher transmission rate, better signal quality, lower signal error rate and so on. The results show that the VM link is 0.126 Gbit/s faster than the VAM on a single channel link, and 15.5 Gbit/s faster in 16-QAM 8 OAM beams multiplexing. The error rate of the received signal under the same conditions at the transmitting end has an improvement of 2 similar to 4 orders of magnitude. The method is simple, convenient to implement, and has a significant improvement in transmission rate. It can provide a wide range of applications in vortex high-capacity communication.