An underwater optical communication system implementing Reed-Solomon channel coding

An underwater optical communications system that implements forward error correction is demonstrated. The system uses a 405 nm diode laser to transmit on-off-keying (OOK) return-to-zero modulated data at a rate of 500 kbps to a photodiode receiver using a (255,129) Reed-Solomon code. The signal is digitized at the receiver and sent to a PC for postprocessing. Experimental measurements collected in an indoor water tank suggest that the coded system can reduce the power required to achieve a bit-error-rate of 10^-4 by approximately 8 dB relative to an uncoded OOK system.