Investigation of Underwater Wireless Optical Communications Links With Surface Currents and Tides for Oceanic Signal Transmission

This report investigated underwater wireless optical communication (UWOC) links in the presence of surface currents and tides. The scenario of surface currents and tides was generated by a sea water tank, a water pipe, and a water pump of different flow rates. It built the oceanic channel of UWOC varied with the salinity and flow rate in the UWOC transmission. The data rate of UWOC links based on a 520-nm laser diode and none-return-to-zero on-off keying (NRZ-OOK) modulation can achieve 3.4 Gb/s at a bit error rate (BER) of 3.78 $\times 10^{-4}$ in 1.8 m long sea water tank when a flow rate reached 1.08 m/s. The BER, eye-diagrams, and received signal optical power measurements showed that both the increasing salinity and flow rate cause the UWOC channel attenuation, thus degrade the performance of UWOC links.