Era of High-Speed Optical Computing is Approaching

November 27 2006

CORVALLIS, Ore. - Physicists at Oregon State University have discovered a way to manipulate the transmission of optical signals in tiny wires, dramatically slowing, stopping or even speeding them up to velocities faster than the speed of light - a major advance that could open the door to a new era of computing and information processing based on optics.

The findings, being published in the journal Physical Review Letters, are an important step toward manipulating light pulses in the same conceptual way that conventional electronics, since the dawn of switches, semiconductors and transistors, has manipulated electrons.

The potential payoff, experts say, might be a new generation of computers, communications or other devices that are no longer hamstrung by the limited speed of electrons - a speed that may seem extraordinarily fast in one sense, but is painfully slow compared to the visionary possibilities of optics.

“At least in theory, computers based on optics might be a million times faster than those used today,” said Viktor Podolskiy, an OSU assistant professor of physics. “This is because the frequency of light is about one million times faster than that of electrons, and the devices we envision would be based on photonics rather than the movement of electrons.”

Some important uses of photonics, of course, are already in common use the fiber-optic cables used for high speed telecommunication, the optical disk readouts used in most PCs. But there currently is no way to manage and manipulate optics in any small device the way that electrons can easily be controlled in everything from computers to cell phones.

“We have some things we can do with photonic structures that give us control over optics somewhat similar to what we have with electrons, but they rely on ultra-high-quality resonances that create severe size problems,” Podolskiy said. “A computer built with this type of approach might be 1,000 times larger, the size of a building instead of a box. It’s not practical.”

However, Podolskiy and Alexander Govyadinov in the OSU Department of Physics found that existing plasmonic nanowires can be combined with a “gain material” - solid or liquid luminescent media that emit light - to squeeze the light to tiny areas, comparable in size with transistors in modern processors, and to further control the speed of the light pulses and manipulate them.

This might mean slowing it, stopping it, or even shaping the light pulse so that information transmitted through the material actually appears on the other end at a speed faster than the light itself - an odd result that seems impossible, but is actually consistent with known physical rules about the propagation of waves.

“This control over the light pulse brings you much closer to an actual optical structure, in which light signals can be synchronized, slowed down, speeded up, or made to function as a transistor,” said Govyadinov. “It’s pretty exciting. It’s going to open up some whole new directions in active plasmonics, with information control and transmission at or around the speed of light.”

The speed of electronic devices, the researchers said, is already starting to hit a wall based on the physical limitations of how fast electrons can move. Photonic devices, by comparison, still have a great deal of work left before they become more practical - optical switches, integration into complex circuits - but they may pick up in speed where electronics left off, and form the basis for entire new industries and applications of the future.

Possible devices that could be made based on optics, the scientists said, include ultra-compact, all-optical data synchronizers, optical buffers, tunable delay lines, transistors, and computers.

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