Group-III-nitride superluminescent diodes (SLDs) 7 are emerging as light sources for white lighting and visible light 8 communications (VLC) owing to their droop-free, low speckle 9 noise, and large modulation bandwidth properties. In this paper, 10 we discuss the development of GaN-based visible SLDs, and ana-11 lyze their electro-optical properties by studying the optical power-12 bandwidth products and injection current densities. The significant 13 progress in blue SLDs and their applications for white light VLC is 14 highlighted. A blue SLD, with an optical power of >100 mW and 15 large PBP of 536 mW•nm, is utilized to generate white light, result-16 ing in a high color rendering index (CRI) of 88.2. In a modulation 17 experiment designed for an SLD-based VLC system, an on-off key-18 ing scheme exhibits a 1.2 Gbps data rate, with a bit error rate of 1.8 19 × 10 −3 , which satisfies the forward error correction criteria. A high 20 data rate of 3.4 Gbps is achieved using the same SLD transmitter, 21 by applying the 16-quadrature-amplitude-modulation (16-QAM) 22 discrete multitone modulation scheme for high-speed white light 23 communication. The results reported here unequivocally point to 24 the significant performance and versatility that GaN-based SLDs 25 could offer for beyond-5G implementation, where white lighting 26 and high spectral efficiency VLC systems can be simultaneously 27 implemented.
B. S. (2020). Gbit/s ultraviolet-C diffuse-line-of-sight communication based on probabilistically shaped DMT and diversity reception. Optics Express, 28(7), 9111.
Abstract:We demonstrated a high-speed 1×2 single-input and multiple-output (SIMO) diffuseline-of-sight (diffuse-LOS) ultraviolet-C (UVC) solar-blind communication link over a distance of 5 meters. To approach the Shannon limit and improve the spectral efficiency, we implemented probabilistically shaped discrete multitone modulation. As compared to a single-input and single-output (SISO) counterpart, we observed significant improvement in the SIMO link in terms of the angle of view of the receiver and the immunity to emulated weather condition. A wide angle of view of ± 9°is achieved in the SIMO system, with up to a 1.09-Gbit/s achievable information rate (AIR) and a minimum value of 0.24 Gbit/s. Moreover, the bit error rate of the SIMO link in emulated foggy conditions is lowered significantly when compared to that of the SISO link. This work highlights the practicality of UVC communication over realistic distances and in turbulent environments to fill the research gap in high-speed, solar-blind communication.
We demonstrated a record-breaking 20.09-Gbit/s WDM-VLC transmission over 1.2 m underwater link with PS-bitloading-DMT modulation. A silicon-substrate multichromatic LED array chip and a feasible optical-filter scheme are proposed for future LED-based WDM-VLC system.
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