Silicon chip works on the speed of light

[Miniver]

From Newscientist.com

A silicon chip that can carry light and even slow it down has been unveiled by IBM researchers in the US.
The chip demonstrates some of the essential techniques for creating high-speed photonic memory, which many researchers believe will one day make electronic memory obsolete in optical communications networks.
Engineers have known for decades that it is more efficient to communicate with photons than electrons. Photons do not interact easily with stray electronic and magnetic fields nor with each other and so are better for long-distance communications. Today most of the world's communications networks rely on light and the optical fibres that carry it.
But there are still difficulties. The reluctance of photons to interact makes them good at carrying information but hard to store. “A photon is one hell of a slippery thing,” says Will Stewart, a photonics engineer at University of Southampton in the UK.
And since the signals in any communications network must be stored while they are amplified and routed, this can only be done by converting light into an electronic signal, processing it as required and then converting it back again.


Slow light

However, physicists have developed two techniques for processing photons. In 1999, Lene Vestergaard Hau at Harvard University in Cambridge, Massachusetts, US, and colleagues, slowed light to the speed of a bicycle by passing it through a cloud of cold atoms.
“Slow light” techniques could be used to buffer optical data, in a way analogous to electronic memory. “The trouble is that they needed a whole roomful of equipment to do it," says Yuri Vlasov, a physicist at IBM’s T J Watson Research Center in Yorktown Heights, New York, US.
Other scientists have created tiny tunnels – called waveguides - that can steer photons through otherwise opaque materials such as silicon. These "nanophotonic" devices can be fabricated in a similar way to electronic chips, which allows for mass production and relatively low cost.


On the edge

Now Vlasov and his IBM colleagues have combined these two techniques. The result is a silicon chip carved with photon waveguides in which the photons can be slowed by a factor of 300 by heating the waveguide to change its optical properties. The idea is that such a device could synchronise data streams by slowing some streams, allowing others to catch up.
But significant challenges remain before photonic chips like this could be of any commercial use.
For example, heating the waveguides takes a long time compared with the switching speed needed in an optical network. And the waveguides have to be carved with an accuracy of 1 nanometre. “That’s right on the edge of what is possible with chip fabrication,” says Vlasov.
Journal reference: Nature (vol 483, p 65)

Linky

[Krell]

I posted it earlier in the year, still a good read


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