Underwater wireless optical communication based on multi-pixel photon counter and OFDM modulation

A underwater wireless optical communication (UWOC) system using a multi-pixel photon counter (MPPC) as the receiver and orthogonal frequency division multiplexing (OFDM) was proposed and experimentally investigated. The MPPC with high sensitivity combined with quadrature amplitude modulation (QAM) OFDM with high spectral efficiency can potentially support a data rate of hundreds of Mbps under a relatively long underwater transmission distance. Although the photoelectric response of each individual pixel in the MPPC is nonlinear due to its intrinsic dead time, the MPPC consisting of thousands of pixels can be operated like a linear photodetector due to the statistical effect. A net data rate of 312.03 Mbps, with a bit error rate (BER) below the forward error correction (FEC) limit, was successfully achieved over a 21-m underwater channel exploiting 32-QAM OFDM modulation.