480-nm distributed-feedback InGaN laser diode for 105-Gbit/s visible-light communication

In this letter, we demonstrate a novel distributed-feedback (DFB) InGaN-based laser diode with narrow-linewidth emission at ~480 nm (sky blue) and its application to high-speed visible-light communication (VLC). A significant side-mode suppression ratio (SMSR) of 42.4 dB, an optical power of ~14 mW, and a resolution-limited linewidth of ~34 pm were obtained under continuous-wave operation. A 5-Gbit/s VLC link was realized using non-return-to-zero on-off keying (NRZOOK) modulation, whereas a high-speed 10.5-Gbit/s VLC data rate was achieved by using a spectral-efficient 16-quadrature-amplitude-modulation orthogonal frequency-division multiplexing (16-QAM-OFDM) scheme. The reported high-performance sky-blue DFB-laser is promising in enabling unexplored dense wavelength-division multiplexing (DWDM) schemes in VLC, narrow-line filtered systems, and other applications where single-frequency lasers are essential such as atomic clocks, high-resolution sensors, and spectroscopy. Single-frequency emitters at the sky-blue wavelength range will further benefit applications in the low-path-loss window of underwater media as well as those operating at the H-beta Fraunhofer line at ~486 nm.