2-Gb/s ultraviolet-light optical wireless communication by InGaN/GaN multi-quantum well dual-function micro-photodetector

Abstract

We demonstrate a series of multifunctional micro-photodetectors (μPDs) designed for high-speed ultraviolet-A-(UVA)-light detection and blue-light illumination based on InGaN/GaN triple-quantum-well devices grown on patterned sapphire substrates. At forward voltage bias, the device operated as a light-emitting diode with a peak emission wavelength of ∼450 nm. When switching to reverse voltage bias, the device exhibited a dual-band responsivity of 0.17 A/W at 370 nm and 0.14 A/W at 400 nm, indicating effective UVA light detection. Furthermore, size-dependent emission and detection behaviors were investigated with the device's active area having radii ranging from 15 to 50 μm. For μPDs, the −3-dB bandwidth increased with the reduced device radius and reached a maximum of 689 MHz for the 15-μm device under −10-V bias. High responsivity and fast modulation speed contributed to 2-Gb/s UVA optical wireless communication based on direct-current-biased optical orthogonal frequency-division multiplexing. The research offers a promising approach to simultaneous high-speed communication and illumination in the UVA-blue-light optical spectral regime, and the dual-band responsivity feature is potentially useful for increasing channel capacity.