In a significant step forward for all-optical computing, physicists build a silicon transistor that works with pure light.
Electrons are pretty good at processing information but not so good at carrying it over long distances. Photons, on the other hand, do a grand job of shuttling data round the planet but are not so handy when it comes to processing it.
As a result, transistors are electronic and communication cables are optical. And the world is burdened with a significant amount of power hungry infrastructure for converting electronic information into the optical variety and vice versa.
So it's no surprise that there is significant interest in developing an optical transistor that could make the electronic variety obsolete.
There's a significant problem, however. While various groups have built optical switches, optical transistors must also have a number of other properties so that they can be connected in a way that can process information.
For example, their output must be capable of acting as the input for another transistor--not easy if the output is a different frequency from the input, for instance. What's more, the output must be capable of driving the input for at least two other transistors so that logic signals can propagate, a property known as fanout. This requires significant gain. On top of this, each transistor must preserve the quality of the logic signal so that errors do no propagate. And so on.
The trouble is that nobody has succeeded in making optical transistors that can do all and can also be made out of silicon.
Today, Leo Varghese at Purdue University in Indiana and a few pals say they've built a device that take a significant step in this direction.
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