Emerging light-emitting diodes for next-generation data communications

Abstract

emiconductor lasers have typically been used to tackle speed and capacity bottlenecks in data communications 1 . However, due to the relatively high manufacturing costs and the relatively complex driver circuits of lasers 2 , as well as eye safety issues, alternative solutions have been sought for future applications in human-centric systems, short-distance communications and indoor wireless data services. Light-emitting diodes (LEDs) are a cost-effective and low-power alternative 2-4 . LED-based links are, in particular, expected to be extensively used in Internet of Things (IoT) and 6G technologies, and in moderate/high-speed photonic interconnects, visible light communications (VLC), underwater communications and accurate indoor positioning applications [2][3][4][5] .The potential use of LEDs in next-generation data communications is driven by the rapid development of energy-efficient LEDs that can function as illumination and signalling devices. The concepts and fundamental principles of LED links are illustrated in Box 1. Micro-LEDs (µLEDs) based on crystalline inorganic III-V semiconductors have been widely examined for communications 2 . Because of advances in epitaxy, lithography and flip-chip techniques 6 , III-V µLEDs have delivered a modulation bandwidth from several hundred megahertz to over one gigahertz 2,7 . A non-polar m-plane InGaN/GaN µLED with a high modulation bandwidth of 1.5 GHz was demonstrated in 2018 7 , and a 1.3 GHz electrical-to-optical bandwidth quantum dot (QD) µLED was recently reported with a data rate of 4 Gbps (ref. 8 ). Nevertheless, conventional approaches are challenged by the high requirements for low size, weight, power and cost of next-generation data communication systems 5,9,10 .Organic semiconductors, colloidal quantum dots (CQDs) and metal halide perovskites offer tailorable optoelectronic properties, mechanical flexibility and low-cost processing 10 . These characteristics make them attractive candidates for use in low-cost and low-power LED links in next-generation integrated and scalable data communication modules. Thus, while conventional inorganic thin-film technologies are likely to continue to play a dominant role in optical communications 9,11 , we believe that LEDs based on these emerging materials can provide a complementary role. In this Review, we examine the development of emerging semiconductor materials for LEDs and colour converters. We first consider the fundamentals of LED-based optical communication systems, and then explore efforts to boost the frequency response and enhance the external quantum efficiency (EQE) of LEDs based on emerging materials. Finally, we consider the challenges that exist in developing these LEDs for practical communication systems.

Colloidal Quantum Dot Light Emitting Diodes at Telecom Wavelength with 18% Quantum Efficiency and Over 1 MHz Bandwidth

“…[ 6 ] To this end, efforts on developing solution processed optoelectronics for free‐space data transfer and IoT applications have been intensified using organic or perovskite semiconductors, yet those operate in the visible or near‐infrared imposing constraints on optical ambient light interference and eye‐safety regulations. [ 7–9 ] Colloidal quantum dots (CQD)‐based optoelectronics recently emerged as one of the most promising technologies to address the market needs in the eye‐safe short‐wave infrared (SWIR) region, thanks to their low‐cost solution processability, large area manufacturing, band gap tunability, and complementary metal‐oxide semiconductor (CMOS) compatibility. [ 1,10,11 ]…”

Flexible Quantum-Dot Color-Conversion Layer Based on Microfluidics for Full-Color Micro-LEDs

“…In recent years, micro-LEDs have been widely used in micro-displays [ 1 , 2 , 3 ], flexible displays [ 4 , 5 ], visible light communication [ 6 , 7 , 8 , 9 ], and optogenetics [ 10 , 11 ]. This is due to their unique advantages, including high brightness, high resolution, low power consumption, and rapid response [ 12 , 13 ].…”

Enhancement of the Modulation Response of Quantum-Dot-Based Down-Converted Light through Surface Plasmon Coupling

“…A faster modulation response or a larger modulation bandwidth (MB) of such a device can lead to a higher communication capability. Recently, visible communication has found broad applications in the areas of indoor links and autonomous cars [ 1 , 2 , 3 , 4 ]. Because of their low cost, light-emitting diodes (LEDs) have been considered as the light sources for visible communications.…”