Dual Readout Mode of Silicon Photomultiplier Array With Diversity Reception for Underwater OWC

High-sensitivity photodetection and suppression of channel fading are promising schemes for underwater wireless optical communication (UWOC). In this letter, we propose an UWOC system based on a single-photon level sensitivity silicon photomultiplier (SiPM) array with diversity reception. We mainly discuss the unique dual readout mode (standard and fast outputs) characteristic of the SiPM manufactured by SensL Technologies or now ON Semiconductor (Onsemi). We extended from a monolithic SiPM to a $2\times 2$ SiPM array spatial diversity structure and analyzed the dual readout case of its parallel subchannels. Experiments demonstrated that the combined standard and fast output for the SiPM array can effectively enhance the signal-to-noise ratio (SNR) because of the bipolar characteristics of the fast output mode. In addition, the incident photon power of the SiPM array and its influencing parameters were investigated.