Harald Haas, the man known as the father of Li-Fi, is a smart guy who probably mastered his times tables a long time ago. This helps explain how the laser company he advises these days recently hit 100 Gbps Li-Fi speeds, with a terabit in sight.
Like LED magazine reported, the 100 Gbps laser-based Li-Fi system that Kyocera SLD Laser (KSLD) demonstrated at the CES consumer electronics show last month was 100 times faster than any Li-Fi demonstration at LED base, and about 700 times faster than standard Li-Fi LED operational.
In short, Li-Fi uses spectra associated with visible light and infrared (IR) to transmit data. The much more well-known and established Wi-Fi uses radio waves. At least Li-Fi could open up a vast frequency for data services, helping to reduce the clutter and signal interference that can plague Wi-Fi.
Li-Fi also promises other potential benefits. One of them is speed. Today’s LED-based Li-Fi isn’t always a clear winner over Wi-Fi. This is one reason why gadget makers have largely refrained from integrating Li -Fi in laptops, tablets and phones. This has resulted in slow adoption of Li-Fi by end users, who must connect dongles to receive and send Li-Fi signals.
But lasers are much faster than LEDs, due to their stimulated emission technology, as opposed to the slower spontaneous emission of LEDs. KSLD’s 100 Gbps is a prime example. Not only is it much faster than Li-Fi LED, but it also provides the white light of the illumination. Increasingly, Li-Fi LED installations operate via IR and do not always provide the simultaneous lighting function, as in a recent Long Island school installation.
So how did KLSD do it?
The short answer: by combining 10 laser diodes, each delivering data at 10 Gbps via a different wavelength from the other. It doesn’t take a really smart guy like Haas to figure out that 10 × 10 = 100. That’s the basic math behind the KSLD approach.
Obviously, there is much more than that.
Towards accelerated commercialization?
Back to Haas, who wears many hats in the Li-Fi industry and academia these days, including serving as KSLD’s senior advisor on Li-Fi laser developments. LEDs had the opportunity to speak to him and KSLD Senior Vice President of Business Development, Paul Rudy, about the 100 Gbps demonstration.
They explained that KSLD transmits with 10 different surface-emitting laser chips, each at a different frequency. Three of them emitted in the blue spectrum, at 430, 440 and 450 nm. The other seven emitted in the IR range, starting at 800 nm and going up to 1100 nm. All 10 were modulated to encode the data. Each fiber optic collided with a transmitter (right in photo), which wirelessly sent all signals to a unit divided into 10 different receivers, each tuned to one of 10 frequencies.
Why bother using 10 different frequencies? Why not deploy 10 chips of the same frequency and thus apparently simplify things? There are two related answers: A set of 10 chips of the same frequency would cause signal conflicts between them. By using 10 non-conflicting wavelengths, KSLD can split data sets conveniently for end users. For example, Li-Fi in an airplane could send data to one passenger at, say, 450nm and to another at 900nm.
“With spatial multiplexing, we can deliver different data to different places if we want to,” Rudy explained. “You can imagine that in an airplane cabin you would have different passenger seats receiving different data.”
The airplane example is a good example, because last August Santa Barbara, Calif.-based KSLD began supplying Seattle-based avionics data networking company Spectrum Networks with Li-Fi components that Spectrum will use to integrate laser Li-Fi into aircraft at approximately 1-2 Gbps, which is currently the fastest commercialized version of KSLD.
Rudy thinks it will take about two to four years to miniaturize the components of the 100 Gbps system into a commercial form and to operate at distances beyond the 1.5 meter length at CES in Las Vegas. .
And things just might pick up speed from there, Haas notes, by applying some simple math.
“We can’t stop at 10,” he said, referring to the number of lasers in an emitter. “We can add 100. And then you can adjust the data rate. So there is a path to a terabit, for example, if you just add more wavelength, miniaturize and make it smaller. It really shows this beautiful ability of light communication, durability of future wireless communication. We have a grand piano. Each wavelength is a key. You just have to play all the keys, and it makes a beautiful piece of music.
Paving the way to lasers
If anyone knows the orchestration of light-based wireless communication, it’s Haas. He is credited with inventing the technology before pioneering its commercialization by co-founding pureLiFi (then called pureVLC) in Edinburgh, Scotland in January 2012, where he is still Chief Scientific Officer. He is a leading academic figure in his development, having been a professor in the field for many years at the University of Edinburgh before leaving in July 2020 to become Distinguished Professor of Mobile Communications at the University of Strathclyde in Glasgow , where he is also the director of the LiFi Research and Development Center.
In the UK, Haas is also contributing to a government-funded group called Terabit Bidirectional Multi User Optical Wireless System for 6G (TOWS), which is striving to reach terabit per second speeds by 2024.
Data transmission is just one part of the technical advancements underway at KSLD that could finally help usher in Li-Fi as a basic wireless communication option. They also manipulate lasers so the light is safe to look at and can be used for general lighting purposes. For example, airliner Li-Fi will use lasers as reading lights as well as data sources.
Rudy and Haas had a lot to say about how they are working on this and the many applications where laser Li-Fi could take hold. Haas even sees integration into solar panels. LED magazine will bring you more.
BRAND HALPER is editor of LEDs Magazine and a journalist specializing in energy, technology and business ([email protected]).
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