Optimal Receiver Design for Orbital Angular Momentum (OAM) Communication via Sampled Beam Analysis

The current generation of satellite constellations utilizes inter-satellite laser links to enhance the capacity of the network backbone. As demand for higher capacity increases, innovative techniques like leveraging the orbital angular momentum (OAM) of light waves will be essential. OAM enables encoding information in the spatial domain, adding to traditional methods such as power, phase, wavelength, and polarization. However, traditional OAM reception methods require capturing a substantial portion of the received beam, which poses a significant challenge for inter-satellite links. The long distances and beam divergence involved in such links result in beam spot at the receiver plane that is too large for a practical telescope to capture. In this paper, we propose a mathematical model and detection technique for binary OAM communication by measuring the power of a small segment of the received OAM beam. By employing an optimization algorithm to minimize the bit error rate (BER), our approach enhances the performance of the communication system. We further extend this model to account for pointing error jitters, which are common in laser satellite communication. Our work lays the foundation for the development of a practical OAM-based communication system in space.