Visible light could be used to transmit data more efficiently than radio waves

New bandwidth record set for laser-based data transmission

A new visible light communication system developed by a team from Saudi Arabia has achieved record bandwidth, providing a data transmission rate of 2Gbit per second.

The team from the King Abdullah University of Science and Technology (KAUST) has devised a system that uses an innovative colour converter based on luminescent materials known as phosphors, which are commonly used in LED lights, and combines them with nanocrystals of perovskite.

"In this work we break the record for data communication using visible light and more impressively produce white light with a very high colour-rendering index of 89, by designing a special colour converter based on hybrid perovskite nanocrystals," said Professor Osman Bakr.

"Our work demonstrates white light as both a lighting source and a system for ultra-high-speed data communications."

Visible light communication (VLC) is frequently considered as one of the possible solutions to the increasing congestion of the radio spectrum, which struggles to cater for the growing demand for wireless data services.

VLC uses lasers or LEDs that look just like traditional lights and transmit information by rapid flashing, imperceptible to the human eye. This flashing transmits a binary code to the receiver possibly at a higher speed and with higher security and energy efficiency than the radio waves.

While the experimental system by the KAUST team achieved speeds of 2Gbit per second, most current Wi-Fi technologies only operate at speeds of a few tens of Mbits per second.

Limited bandwidth has so far been a major obstacle preventing practical use of VLC.

The design of the colour converter by the KAUST team overcomes this problem. While phosphors used in the system would only provide a limited bandwidth of maximum 12 megahertz, the additional use of perovskite greatly increases this value. As a result, the new colour converter provides bandwidth that is 40 times greater than what is available through commercial converters.

This bandwidth is also larger than that of non-phosphor-based colour converters that scientists have recently been investigating, which have a bandwidth in the range of 40-200 MHz.

"In this bandwidth hungry era, there will be a continuous push by consumers for VLC systems with higher bitrates," said Boon Ooi, the system’s co-invetor. "We believe that white light generated by semiconductor lasers will one day replace the LED white light bulb for energy-efficient lighting. To achieve this objective, we set our long-term goal to develop nanocrystals that can convert high-energy excitation photons from semiconductor lasers to Red-Yellow-Green-Blue (RYGB) lights at ultra-short photon lifetime.”

The device, which emits a very pleasant natural-looking light, could also be used as an indoor light source or optical display.

The research was published in the journal ACS Photonics.

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