16-mode OAM shift keying FSO communication using multi-plane light convertor

The utilization of orbital angular momentum-shift keying (OAM-SK) has elicited broad interest in recent years due to its potential for high-dimensional communication through the exploitation of the orthogonality of OAM modes. However, the application of OAM-SK in free-space optical (FSO) communication systems is currently hindered by several critical challenges. These include elevated bit error rates (BER) induced by atmospheric turbulence (AT), limited data transmission rates attributable to the inherent constraints of existing demodulation techniques, and the high computational complexity associated with advanced algorithms required for accurate signal recovery. Given these limitations, the development of OAM-SK FSO communication systems that incorporate turbulence mitigation capabilities while maintaining simplicity and high-speed performance is of considerable practical significance. In this work, we have designed and simulated a free-space OAM-SK modulation/demodulation system with a multi-plane light converter (MPLC) optimized designed by wavefront matching method. A 16-bits symbol sequence encoded with distinct OAM modes was transmitted across a simulated free-space channel with a path length of ~2 meters. The received signal was subsequently demodulated at the receiver end. Our simulation results demonstrate that the proposed system can achieve a bit error rate (BER) lower than 1×10−5 under medium and low turbulence conditions. It indicates that the integration of MPLC effectively mitigates the adverse effects of atmospheric turbulence on OAM mode propagation, thereby enabling reliable high-dimensional communication.