Multi‐Pixel Photon Counter Enabled High‐Sensitivity Detecting for Underwater Wireless Optical Communication

This paper presents a robust Underwater Wireless Optical Communication (UWOC) system designed to achieve long‐range transmission by overcoming the limitations of conventional receivers in turbid and high‐attenuation channels. The system features a novel architecture that synergizes high‐order 16‐Quadrature Amplitude Modulation (16‐QAM) modulation with a high‐sensitivity Multi‐Pixel Photon Counter (MPPC) receiver. To enable reliable data recovery from ultra‐weak signals (−40 dBm) typical of long‐distance links. This paper implemented a specialized FPGA‐based digital signal processing unit featuring carrier synchronization and Gardner timing recovery to suppress stochastic noise. Experimental results demonstrate that the system achieves a data rate of 16 Mbit/s and successfully maintains a Bit Error Rate (BER) below the 7% hard decision forward error correction(HD‐FEC) limit even at a received optical power as low as −40 dBm. This performance significantly extends the dynamic range of UWOC links, validating the system's capability for reliable long‐range transmission under extreme signal attenuation.