Laser-Driven High-Brightness Green Light for Underwater Wireless Optical Communication

摘要

Green light is generally used as the transmitter of underwater wireless opticalcommunication (UWOC) system, but the currently available light-emitting diode(LED)-based green light has a poor luminous flux density (i.e., low brightness)and a low wall-plug efficiency (WPE), known as the “green gap”. In this work,it is proposed to produce the laser-driven green light by using blue laser diodesto pump the narrow-band green-emitting β-Sialon phosphor-in-glass (PiG) film.The dominant wavelength of the laser-driven green light can be tuned in therange of ≈520–540 nm, required for UWOC, by controlling the phosphor contentat ≈60–80% and the film thickness at ≈150–185 μm. By introducing highlyreflective TiO2 into the PiG film, the laser-driven green light exhibits a maximumluminous flux density of 1260 lm mm~(?2) under blue laser excitation with a powerdensity of 15.49 W mm~(?2). For UWOC application, the green light is demonstratedto have a modulation bandwidth of 1.76 MHz, a high WPE of 8.7%, and along transmission distance of ≈61.6 m. This work suggests that the laser-drivenhigh-brightness green light will be a promising light source for UWOC.