Bidirectional White-Lighting WDM VLC–UWOC Converged Systems

A bidirectional white-lighting wavelength-division-multiplexing (WDM) visible light communication (VLC)-underwater wireless optical communication (UWOC) converged system with an office-level white light illumination of 514 lux and a symmetric downstream/upstream data rate of 150 Gb/s is demonstrated successfully. Red, green, and blue (RGB) laser diodes with two-stage light injection and optoelectronic feedback schemes are operated to provide bidirectional acceptable office-lighting and high-transmission-rate. White light is created/separated by combining/dispersing RGB lights utilizing two cascaded transmission gratings at the transmitting/receiving side. By employing PAM4 modulation and RGB triple-light WDM technique, the transmission rate is enhanced remarkably to 150 Gb/s for downlink/uplink transmission. Acceptable office-lighting (>500 lux) is attained through 3 m plastic optical fiber transport. Additionally, good bit error rate performance of 10
^-9
and accepted PAM4 eye diagrams are obtained over 10 m free-space transmission with 5 m ocean underwater link. The bidirectional white-lighting WDM VLC-UWOC converged system demonstrated here is beneficial for the development of white-lighting with high-speed optical wireless communications.