Gallium nitride (GaN) laser diodes are becoming popular sources not only for lighting but for applications ranging from communications to quantum. This paper presents the use of a commercial, off-the-shelf laser diode, with an emission wavelength of 450 nm, for visible light communication, both in free space and for underwater scenarios. Data rates up to 15 Gbit/s have been achieved by making use of orthogonal frequency division multiplexing (OFDM). In addition, distributed feedback (DFB) lasers have been realised emitting at a single wavelength which lend themselves towards applications where high spectral purity is crucial such as atomic clocks or filtered free space transmission systems. These devices have the grating structure etched into the sidewall of the ridge and work is ongoing to measure the linewidth of these lasers with the intended application of cooling Sr+ ions.
Scott Watson, Steffan Gwyn, Shaun Viola, Giovanni Giuliano, Thomas J. Slight, Szymon Stanczyk, Szymon Grzanka, Amit Yadav, Duncan Rowe, Leslie Laycock, Kevin E. Docherty, Edik Rafailov, Piotr Perlin, Steve Najda, Mike Leszczynski, and Anthony E. Kelly.