DVS enabled fast beam tracking for underwater wireless laser communication

Underwater wireless laser communication (UWLC), as a key technology in deep-sea exploration and underwater operations, has attracted the attention of many researchers. Maintaining stable and high-data-rate UWLC has been eagerly pursued. However, in the practical implementation of UWLC, underwater disturbances, flow and waves may inevitably disable the operation of the underwater communication link. Normally, the underwater disturbances can take place as fast as the millisecond time scale. Therefore, fast closed loop tracking technologies for stable UWLC links are necessary to mitigate the underwater interference. In this paper, we propose a fast beam tracking scheme based on a dynamic vision sensor (DVS), for real-time fast tracking for UWLC links when encountering underwater disturbances. By combining a high-time-resolution DVS with a proportional-integral-derivative (PID) control algorithm, the beam tracking system can accurately detect the centroid offset of light spots with a time resolution of <1 ms, which is the best temporal resolution for underwater beam acquisition to the best of our knowledge. Real-time beam alignment through a 11-ms closed loop control is achieved for UWLC links. This experimentally validates that the combination of the high temporal resolution of DVS and PID algorithms is able to deliver a simple and fast tracking method, which may be critical for future breakthroughs in tracking technologies for UWLC links.