Long-distance underwater wireless optical communication with a single photon-counting system

We proposed a long-distance underwater wireless optical communication with a single photon-counting system in a laboratory environment by using non-return to zero on-off keying modulation. The system successfully achieved a data rate of 1Mbps through a 15m PVC tube by adding in 80dB attenuator and using a pigtailed fiber 450nm blue laser diode. The water channel was measured to have an attenuation coefficient comparable to clean seawater. The experimental results show that under condition of only average 1.2 photons in single optical pulse, photon counting UOWC with a BER of 1. 6×10−4 and a baud rate of 1 Mbps can be achieved. Based on the measured minimum required power in the water channel, the transmission performance was predicted to be 140m and 310m in the clean seawater and pure seawater, respectively.