Underwater Wireless Video Communication Using Blue Light

Abstract

Interest in wireless blue light communication is increasing because this technology shows promise for realizing high-speed, long-distance and full-duplex underwater communication. Here, we demonstrate an underwater wireless communication system, OceanLink, to establish full-duplex data transmission using blue light. Both the transmitter and receiver are housed together to independently transmit and receive data simultaneously. To obtain a longer transmission distance and better light field distribution, the transmitter is composed of an array of three light-emitting diode (LED) units with the dominant emission peak wavelength centered around 452 nm, each of which merges four LEDs in series. These LEDs are synchronously driven via a main processing unit to pulse blue light using a nonreturn-to-zero on-off keying modulation scheme. At the receiver, light passes through a neutral density (ND) filter and a focus lens to hit the transducer, which converts light signals into electrical signals. The waterproof OceanLink achieves a bidirectional communication rate of 4 Mbps with a wireless transmission distance of 12 m in a swimming pool, wherein the ND factor is 256 and the nephelometric turbidity unit is 1.7. Thus, real-time full-duplex underwater video communication is experimentally demonstrated.