Abstract
High-speed visible light communication (VLC), as a cutting-edge supplementary solution in 6G to traditional radio-frequency communication, is expected to address the tension between continuously increased demand of capacity and currently limited supply of radio-frequency spectrum resource. The main driver behind the high-speed VLC is the presence of light emitting diode (LED) which not only offers energy-efficient lighting, but also provides a cost-efficient alternative to the VLC transmitter with superior modulation potential. Particularly, the InGaN/GaN LED grown on Si substrate is a promising VLC transmitter to simultaneously realize effective communication and illumination by virtue of beyond 10-Gbps communication capacity and Watt-level output optical power. In previous parameter optimization of Si-substrate LED, the superlattice interlayer (SL), especially its period number, is reported to be the key factor to improve the lighting performance by enhancing the wall-plug efficiency, but few efforts were made to investigate the influence of SLs on VLC performance. Therefore, to optimize the VLC performance of Si-substrate LEDs, we for the first time investigated the impact of the SL period number on VLC system through experiments and theoretical derivation. The results show that more SL period number is related to higher signal-to-noise ratio (SNR) via improving the wall-plug efficiency. In addition, by using Levin-Campello bit and power loading technology, we achieved a record-breaking data rate of 3.37 Gbps over 1.2-m free-space VLC link under given optimal SL period number, which, to the best of our knowledge, is the highest data rate for a Si-substrate LED-based VLC system.
Highlights
As the emergence of the innovative technologies requiring for ultra-high communication data rate, the wireless communication research focus has gradually moved to 6G, which is likely to offer a two orders of magnitude bit-rate growth over 5G [1]
The linear power response curve could partially prevent the undesired nonlinear effect generated during the electro-optical conversion process, which improves the available signal-to-noise ratio (SNR) of visible light communication (VLC) system
It is the growth of V-shaped pits as the increase of Superlattice interlayers (SLs) period number that contributes to this improvement
Summary
As the emergence of the innovative technologies requiring for ultra-high communication data rate (such as artificial intelligence, virtual reality and the Internet of Things), the wireless communication research focus has gradually moved to 6G, which is likely to offer a two orders of magnitude bit-rate growth over 5G [1]. The current wireless communication network suffers from shortage of radio-frequency (RF) spectrum resources, hardly to reach giga-bit-per-second data rate. The LED-based VLC system has reached the data rate of Mega-bit-per-second using off-the-shelf LEDs [6], but these LEDs are originally designed for daily lighting where their bandwidth is only several Mega-Hertz (MHz) [7]. If the LED is well designed (e.g. reducing LED area), the achievable data rate could reach Giga-bit-per-second level [8]. The InGaN/GaN vertical LED grown on silicon (Si) substrate, known as Si-substrate LED, is a promising alternative to high-speed VLC transmitter, which could support over 10-Gbps VLC underwater link [9], and offer effective white-light illumination thanks to its Watt-level output optical power and the competitive external quantum efficiency within all visible light spectrum
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