Multi-tasking micro-lights could spark a communications revolution

Jan 25, 2013

Tiny LED lights now being developed could deliver Wi-Fi-like internet communications, while simultaneously displaying information, and providing illumination for homes, offices and a whole host of other locations.

Over the next four years, with Engineering and Physical Sciences Research Council (EPSRC) funding, a consortium of UK universities led by the University of Strathclyde will be developing this to help unleash the full potential of '' – the transmission of using visible light rather than the and currently in use.

Although the potential possibilities offered by Li-Fi are already being explored all over the world, this EPSRC-funded consortium is pursuing a radical, distinctive vision that could deliver enormous benefits.

Underpinning Li-Fi is the use of light emitting diodes (LEDs), a rapidly spreading which is expected to become dominant over the next 20 years. Imperceptibly, LEDs flicker on and off thousands of times a second. By altering the length of the flickers, it is possible to send to specially adapted PCs and other – making Li-Fi the digital equivalent of Morse Code. This would make the visible part of the available for internet communications, easing pressure on the increasingly crowded parts now used.

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But rather than developing Li-Fi LEDs around 1mm2 in size, which other researchers around the world are concentrating on, the EPSRC-funded team is developing tiny, micron-sized LEDs which potentially offers a number of major advantages:

Firstly, the tiny LEDs are able to flicker on and off 1,000 times quicker than the larger LEDs this also means they can transmit data more quickly. Secondly, 1,000 micron-sized LEDs would fit into the space occupied by a single larger 1mm2 LED, with each of these tiny LEDs acting as a separate . A 1mm2 sized array of micron-sized LEDs could therefore communicate 1,000 x 1,000 (-i.e. a million) times as much information as one 1mm2 LED.

Moreover, each micron-sized LED would act as a tiny pixel. So one large LED array display (e.g. used to light a living room, a meeting room or the interior of an aircraft), could also be used as a screen displaying information at exactly the same time as providing internet communications and the overall room lighting.

Professor Martin Dawson of the University of Strathclyde, who is leading the initiative, says: "Imagine an LED array beside a motorway helping to light the road, displaying the latest traffic updates and transmitting internet information wirelessly to passengers' laptops, netbooks and smartphones. This is the kind of extraordinary, energy-saving parallelism that we believe our pioneering technology could deliver."

Eventually, it could even be possible for the LEDs to incorporate sensing capabilities too. For example, your mobile phone could be equipped with a flash that you point at a shop display where everything has been given an electronic price tag, and the price of all the items and other information about them would show up on your phone's display.

To enable the remarkable potential to be realised, the consortium has drawn together a unique breadth and depth of expertise unmatched by any other Li-Fi research team anywhere in the world.

Professor Dawson says: "The Universities of Cambridge, Edinburgh, Oxford and St Andrews are all working with us, bringing specific expertise in complementary areas that will equip the consortium to tackle the many formidable challenges involved – in electronics, computing and materials, for instance – in making this vision a reality. This is technology that could start to touch every aspect of human life within a decade."      

Explore further: For Google's self-driving cars, learning to deal with the bizarre is essential

More information: The term Li-Fi was coined by one of the partners in the project, Professor Harald Haas from the University of Edinburgh in a TED talk in July 2011. For more information: bit.ly/tedvlc

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Telekinetic
3 / 5 (2) Jan 25, 2013
"Professor Martin Dawson of the University of Strathclyde, who is leading the initiative, says: "Imagine an LED array beside a motorway helping to light the road, displaying the latest traffic updates and transmitting internet information wirelessly to passengers' laptops, netbooks and smartphones."

Forget the passengers, this will add even more distractions for the sixteen year-old driver's attention away from his texting. Think of all of the spelling errors!
Eikka
1.5 / 5 (2) Jan 25, 2013
could also be used as a screen displaying information at exactly the same time as providing internet communications and the overall room lighting.


Well, you have an obvious compromize here.

For the array of tiny LEDs to work as separate communication channels, each has to be of different color. Otherwise they'd get mixed up. If you pick the colors evenly across the spectrum, you get a lamp that looks white. If you want to make it blue, or red, or green, you have to shut down most of the communications channels and only turn on those that correspond to a narrow band of wavelenghts. Since only a portion of the micro-LEDs are shining at this point, the brightness of the light source is also compromized.

So it's not going to work very well as a graphical display, because the moment you display a specific color, the brightness and data bandwidth of the pixel drops dramatically.

It will work as an excellent lamp though, because it has all the visible spectrum in the light.
antialias_physorg
3 / 5 (2) Jan 25, 2013
Otherwise they'd get mixed up.

There could be other ways to discern them (though different wavelengths are probably cheapest).
Different polarization filters.
Or, if you use laser diodes instead of chaotic LED light you could have them operating in different phases at the same wavelength.
If you pick the colors evenly across the spectrum, you get a lamp that looks white

I'd drop the viewing aspect and simply go to infrared.
Eikka
not rated yet Jan 25, 2013
you could have them operating in different phases at the same wavelength.


There's the problem that you can't control the phase of a simple laser diode. Once it starts lasing, the phase is what you get by chance, and temperature effects make it drift around.

You'll have problems with polarization too due to the fact that reflected light in the room will have the polarization altered, so you have a tremendous amount of noise bouncing around the room making it rather impossible to recieve the signal without pointing the reciever straight at the lamp and shielding it from the interference.

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