Beyond 25 Gbps optical wireless communication using wavelength division multiplexed LEDs and micro-LEDs.

In this Letter, high-speed optical wireless communication (OWC) with three light-emitting diodes (LED) and five micro-LEDs (µLEDs) is proposed as a proof-of-concept wavelength division multiplexing (WDM) system. It covers a wide spectrum from deep ultraviolet (UV) to visible light and thus could offer both visible light communication (VLC) and UV communication simultaneously. An aggregated data rate of up to 25.20 Gbps over 25 cm free space is achieved, which, to the best of our knowledge, is the highest data rate for LED-based OWC ever reported. Among them, the five µLEDs offer a data rate of up to 18.43 Gbps, which, to the best of our knowledge, is the highest data rate for µLED-based OWC so far. It shows the superiority and potential of µLEDs for WDM-OWC. Additionally, a data rate of 20.11 Gbps for VLC is achieved.

High bandwidth series-biased green micro-LED array toward 6 Gbps visible light communication.

In this Letter, a record modulation bandwidth of 1.31 GHz was achieved by a 10 µm c-plane green micro light emitting diode (micro-LED) at a current density of 41.4 kA/cm2. Furthermore, by designing a series-biased 20 µm micro-LED with higher light output power, combined with an orthogonal frequency division multiplexing modulation scheme, a maximum data rate of 5.789 Gbps was achieved at a free-space transmission distance of 0.5 m. This work demonstrates the prospect of c-plane polar green micro-LED in ultrahigh-speed visible light communication, which is expected to realize a high-performance wireless system in the future.

4.0 Gbps visible light communication in a foggy environment based on a blue laser diode.

Fog has a strong attenuation effect on the optical channel, which will greatly degrade the performance of visible light communication (VLC). Studying the effect of the fog on communication performance is crucial to realize outdoor VLC for next generation networks, but there is little research on this topic. In this work, the transmission characteristics of visible light band in the foggy channel were measured and a high-speed VLC system based on a 450 nm blue laser diode (LD) and 16-ary quadrature amplitude modulation orthogonal frequency division multiplexing (16-QAM-OFDM) in the artificial fog environment was demonstrated experimentally. Through a foggy channel of 60 cm, a maximum data rate of up to 4 Gbps was achieved at the pass loss of 13.06 dB with a bit error rate (BER) of 3.5 × 10-3 below the forward error correction (FEC) limit (3.8 × 10-3), which was the highest data rate ever reported for VLC in the foggy channel. Even at a higher pass loss of 17.32 dB, the proposed system still could achieve a data rate of 2.84 Gbps with a BER of 2.8 × 10-3. Further extending the distance to 16.9 m for a more practical application, a data rate of 2.0 Gbps was also demonstrated successfully.

Computational temporal ghost imaging for long-distance underwater wireless optical communication.

This work proposes an underwater wireless optical communication (UWOC) system based on computational temporal ghost imaging (CTGI) and a low-bandwidth high-sensitivity avalanche photodiode. After measuring the attenuation coefficient of water, a series of neutral density filters is used to attenuate the optical power to estimate the distance of UWOC. Experimental results show that under the conditions of 4 GHz transmitting frequency and 144.37 m estimated distance, through CTGI, we can achieve error-free transmission, and the peak signal-to-noise ratio is much higher than on-off keying. Additionally, after adopting the segmented reconstruction method, under the condition of 4 GHz transmitting frequency and 193.10 m estimated distance, we can also achieve error-free transmission. At the same time, the relationship between UWOC performance and the number of segments is also studied. This research provides a novel UWOC technique that enables high-frequency transmission signals to be detected by a low-bandwidth photodetector for long-distance UWOC.

2 Gbps free-space ultraviolet-C communication based on a high-bandwidth micro-LED achieved with pre-equalization.

In this Letter, we experimentally achieve high-speed ultraviolet-C (UVC) communication based on a 276.8 nm UVC micro-LED. A record ${-}{{3}}\;{\rm{dB}}$ optical bandwidth of 452.53 MHz and light output power of 0.854 mW at a current density of ${{400}}\;{\rm{A/c}}{{\rm{m}}^2}$ are obtained with a chip size of 100 µm. A UVC link over 0.5 m with a data rate of 2 Gbps is achieved using 16-ary quadrature amplitude modulation orthogonal frequency division multiplexing and pre-equalization, and an extended distance over 3 m with a data rate of 0.82 Gbps is also presented. The demonstrated high-speed performance shows that micro-LEDs have great potential in the field of UVC communication.