Cornell University researchers have demonstrated for the first time a device that allows one low-powered beam of light to switch another on and off on silicon, a key component for future "photonic" microchips in which light replaces electrons.
Photonics on silicon has been suggested since the 1970s, and previous light-beam switching devices on silicon have been demonstrated, but they were excessively large (by microchip standards) or have required that the beam of light that does the switching be very high-powered. The approach developed by Michal Lipson, Cornell assistant professor of electrical and computer engineering, confines the beam to be switched in a circular resonator, greatly reducing the space required and allowing a very small change in refractive index to shift the material from transparent to opaque.
The advancement of nanoscale fabrication techniques in just the past few years has made it possible to overcome some of the traditional limitations of silicon photonics, Lipson said. Photonic circuits will find their first application in routing devices for fiber-optic communications, she suggests. At present, information that travels at the speed of light through optical fiber must be converted at the end into electrical signals that are processed on conventional electronic chips, then in many cases converted back into optical signals for retransmission, an extremely slow process. The all-optical switch makes it possible to route these signals without conversion.
Bill Steele | EurekAlert!
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