Telecommunications

Nanocrystals speed up Wi-Fi-emitting LEDs

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Researchers at KAUST have developed a nanocrystal that can boost the data transmit rates through visible white light to 2 Gbps
KAUST 2016
Researchers at KAUST have developed a nanocrystal that can boost the data transmit rates through visible white light to 2 Gbps
KAUST 2016
When a blue laser hits the nanocrystals, they emit green and red light, and the three colors together form white, while boosting the data transfer rates at the same time
KAUST 2016

Communication technologies like Bluetooth and Wi-Fi operate on invisible radio waves, but transmitting data on wavelengths we can see might turn out to be more efficient and secure. Researchers at King Abdullah University of Science and Technology (KAUST) have developed a nanocrystal that helps boost data speeds transmitted through a visible light LED up to 2 Gbps – while pleasantly lighting the room.

Only a fraction of the electromagnetic spectrum is visible to the human eye, and making use of those wavelengths could lead to faster, safer and more efficient wireless data systems. With so many wireless signals jostling for the attention of devices, certain frequencies can become clogged, and radio waves can interfere with sensitive equipment used for navigation or in hospitals. Visible-light communication (VLC) systems may help bypass those issues.

Currently, VLC devices are based on LEDs which use phosphorus to turn some of the blue light emitted by a diode into red and green. When combined, the red, blue and green form white light, comfortably lighting a room while providing a wireless signal. But this technique has its limits.

"VLC using white light generated in this way is limited to about one hundred million bits per second," says Boon Ooi, a KAUST Professor of Electrical Engineering, though a University of Virginia study reached 300 Mbps, and Siemens managed 500 Mbps. Pennsylvania State University has even hit 1.6 Gbps, albeit using invisible infrared light.

The KAUST researchers have achieved 2 Gbps using visible light, converting the colored light into white using nanocrystals instead of phosphorus. These crystals are eight nm long and made of cesium lead bromide, and when hit by a blue laser, emit green light. An incorporated nitride phosphor emits red light, and the three colors combine to form the white, room-illuminating light that's reportedly comparable to that of existing LEDs.

When a blue laser hits the nanocrystals, they emit green and red light, and the three colors together form white, while boosting the data transfer rates at the same time
KAUST 2016

Data is transferred through a series of quick flashes, imperceivable to the human eye yet loud and clear to a receiving sensor. That's because in these nanocrystals, the optical processes operate on a time-scale of about seven nanoseconds, meaning the optical emission of the light operates at a frequency of 491 MHz. That in turn allows the data to be transmitted at 2 Gbps, although other research indicates VLC could go as fast as 10 Gbps.

"The rapid response is partly due to the size of the crystals," says Osman Bakr, Associate Professor at KAUST. "Spatial confinement makes it more likely that the electron will recombine with a hole and emit a photon."

The research was published in the journal ACS Photonics.

Source: KAUST via Eurekalert

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2 comments
Alien
While the use of this technology would necessitate 'line of sight' communication in, say, a home or office 'wifi' system, the use of optical wavelengths should presumably enable the signals also to be transmitted via fibre optics and so be able to deliver increased data speeds in 'normal' fibre Internet communications. Hence I would hope the use of VLC can increase data speeds across the board.
Michael Flower
Sounds Like Li-Fi...