Prototype system for underwater wireless optical communications employing orbital angular momentum multiplexing

Abstract

The orbital angular momentum (OAM) multiplexing technology is an essential method to boost underwater wireless optical communication (UWOC) capacity. However, state-of-art UWOC systems are often demonstrated in the laboratory using bulky and high power-consumption instruments, which can be impractical in a realistic environment. In this work, we propose, design and demonstrate a compact and energy-efficient OAM multiplexing UWOC prototype with complete packaging. Indeed, we improve the signal generation, modulation, receiving and processing components by employing the integrated programmable chips. We also employ two geometric phase Q-plate chips as an OAM multiplexer and de-multiplexer, respectively. Owing to the improvement of these components and the optical design, we package the complete UWOC system in two 65cm×35cm×40cm boxes with the power consumption of 20W. Our experiment demonstrates such a completely packaged prototype can support two 625Mbit/s channels (OAM+3, OAM-3) multiplexing in a 6-meter underwater environment with fidelity.