Phase Coherent Digital Communications for Wireless Optical Links in Turbid Underwater Environments

Previous studies by the authors have included a theoretical and experimental investigation of the spatial distribution of an optical signal used for communications in underwater scattering environments. Presented here is an experimental study of how scattering affects the temporally encoded information bearing component of the optical signal. Short range underwater optical links employing BPSK, QPSK, 8- PSK, 16-QAM, and 32-QAM modulation are implemented in a laboratory setting, yielding data rates up to 5 Mb/s. The effect of link quality is examined versus water turbidity.