Experimental demonstration of over 14 AL underwater wireless optical communication

Turbidity of water significantly affect the system performance of underwater wireless optical communication (UWOC). In this letter, we proposed and experimentally demonstrated a loss-tolerant UWOC system using a compact high-power 520-nm laser diode (LD) and a highly sensitive silicon photomultiplier (SiPM). The LD is directly modulated by the on-off keying-non-return-to-zero (OOK-NRZ) data. A precise collimation system is designed in the transmitter so that the maximum beam divergence angle is fixed at 0.75 mrad. The performance of the proposed system is investigated over a 24-m underwater channel with different attenuation lengths (ALs) mimicking the different levels of water turbidity in coastal water. Experimental results show that the data rates of 20 Mbps, 40 Mbps, 80 Mbps and 100 Mbps can be achieved under 14.3 AL, 13.2 AL, 13.2 AL and 12.3 AL with bit error rates (BERs) lower than the forward error correction (FEC) limit.