7.4-Gbit/s Visible-Light Communication Utilizing Wavelength-Selective Semipolar Micro-Photodetector

Visible light communication (VLC) has drawn significant attention in recent years. Though high-speed visible-light sources have seen significant advances, commercially available photodetectors have low wavelength selectivity and modulation bandwidth in the near-violet-blue wavelengths, making them a bottleneck in VLC links. Here we show a record 7.4-Gbit/s visible-light communication link using a wavelength-selective, (\mathbf {20}\overline {21})-oriented, semipolar InGaN/GaN multiple-quantum-well micro-photodetector (\mu PD) on GaN substrate. This is achieved by leveraging on the unique photodetection properties of semipolar \mu PDs, combined with an optimized communication system utilizing bit- and power-loading schemes in orthogonal frequency-division multiplexing (OFDM) modulation over a 2-GHz bandwidth. We used a 405-nm violet laser diode transmitter as the responsivity of the \mu PD was highest within the responsivity range of 360 - 420 nm. The investigation fully demonstrated the feasibility and favorable choice of semipolar InGaN/GaN \mu PDs for multi-Gbit/s optical wireless communication.