Future bundles of data could cruise through optical cables at 1Tb/sec, according to the guys at Intel. The chip maker's researchers have just successfully trialled a 50Gb/sec data connection using photonics, and they reckon that's just the beginning.
The key technology behind the achievement is the hybrid silicon laser, which Intel first started work on in 2006 with Professor Bowers at the University of Santa Barbara. "The idea is that you take silicon and Indium Phosphide, and we bond Indium Phosphide to the silicon," explained the director of Intel's Photonics Technology Lab, Dr Mario Paniccia, at the presentation.
In this case Indium Phosphide is needed to emit the photons, but these are controlled by silicon. "If you can imagine 100 [silicon] waveguides that I bond Indium Phosphide to, and the Indium Phosphide will emit light everywhere, the light automatically comes down into the silicon waveguide," explained Paniccia. "So with one bond I can actually create hundreds or thousands of lasers."
Work on the hybrid laser then went a step further in 2008, when Intel experimented with etching gratings into the silicon to act as mirrors. "Depending on the design of those gratings, they will reflect a specific wavelength," says Paniccia.
"So what I'm able to do now is have ten different waveguides, and with different gratings I can then choose different wavelengths." The result is a laser system, in which Paniccia says "performance is now 100 per cent dictated by silicon." It's also hoped that the cheap cost of mass-produced silicon will also help to bring down the cost of optical connections.
Intel has now managed to turn the hybrid laser into a data transfer device, by integrating four of them into a transmitter chip. This chip takes the standard electrical data given to it, and splits it into four 12.5Gb/sec channels. Each channel is handled by a hybrid laser via a modulator, and a multiplexer then combines the four channels into a single 50Gb/sec stream that can travel over a fibre optic cable.
Of course, it then has to go through the reverse process at the other end, courtesy of Intel's receiver chip. Once the optical signal hits the receiver, it goes into a demultiplexer, where it's once again split into four independent channels, which are each output as electrical signals at 12.5Gb/sec again.
According to Intel, the 50Gb/sec photonic data transfer system was left running for over a day, during which over a petabit of data was transferred, and there wasn't a single error on the system.
This is a good test that the technology works, but future photonic data connections could be massively quicker, thanks to basic parallelism. Intel says transmitting 40Gb/sec per channel, rather than 12.5Gb/sec, won't be a problem, and when you multiply that by 25 channels you end up with a super-fast 1Tb/sec connection. According to Intel, such a connection could enable you to download the whole printed collection of the Library of Congress in one and a half minutes.
The potential of such a high-speed connection has huge implications for the future of computing. Intel predicts that future data centres could just have a single shared box containing many terabytes of RAM and several CPUs, which could then be accessed by any computers via a single optical connection.
Paniccia stresses this is currently a "concept" project, and no official products have been announced yet. However, it looks as though the technology isn't far off. "It's not ten years out," said Paniccia, adding "I think you will see photonics-type commercialisation in the next three to five years."
Data centres will be the first area to see the technology, but the photonics looks set to pervade every area of our computing lives in the years to come. "'In the future everything will be connected by fibre," says Paniccia.