31.38 Gb/s GaN-based LED array visible light communication system enhanced with V-pit and sidewall quantum well structure

Although the 5G wireless network has made significant advances,it is not enough to accommodate the rapidly rising requirement for broader bandwidth in post-5G and 6G eras.As a result,emerging technologies in higher frequencies including visible light communication(VLC),are becoming a hot topic.In particular,LED-based VLC is foreseen as a key enabler for achieving data rates at the Tb/s level in indoor scenarios using multi-color LED arrays with wavelength division multiplexing(WDM)technology.This paper proposes an optimized multi-color LED array chip for high-speed VLC systems.Its long-wavelength GaN-based LED units are remarkably enhanced by V-pit structure in their efficiency,especially in the“yellow gap”region,and it achieves significant improvement in data rate compared with earlier research.This work investigates the V-pit structure and tries to provide insight by introducing a new equivalent circuit model,which provides an explanation of the simulation and experiment results.In the final test using a laboratory communication system,the data rates of eight channels from short to long wavelength are 3.91 Gb/s,3.77 Gb/s,3.67 Gb/s,4.40 Gb/s,3.78 Gb/s,3.18 Gb/s,4.31 Gb/s,and 4.35 Gb/s(31.38 Gb/s in total),with advanced digital signal processing(DSP)techniques including digital equalization technique and bit-power loading discrete multitone(DMT)modulation format.