The researchers split a beam of light into two separate beams as it passed through silicon, then used a novel transistor-like device to hit one beam with an electric charge, inducing a "phase shift." When the two beams of light are recombined, the phase shift induced between the two arms makes the light exiting the chip go on and off at over one gigahertz (one billion bits of data per second), 50 times faster than previously produced on silicon. This on-and-off pattern of light can be translated into the 1's and 0's needed to transmit data. The findings are reported in the current issue of Nature.
"This is a significant step toward building optical devices that move data around inside a computer at the speed of light," said Patrick Gelsinger, senior vice president and CTO at Intel. "It is the kind of breakthrough that ripples across an industry over time, enabling other new devices and applications. It could help make the Internet run faster, build much faster high-performance computers and enable high-bandwidth applications like ultrahigh-definition displays or vision-recognition systems."
The fabrication of commercial optical devices has favored expensive and exotic materials requiring complex manufacturing, thus limiting their use to such specialty markets as wide-area networks and telecommunications. Intel said its fabrication of a fast silicon-based optical modulator with performance that exceeds 1 GHz demonstrates the viability of standard silicon as a material for bringing the benefits of high-bandwidth optics to a much wider range of computing and communications applications.
The 1 GHz of today's experimental device equates to a billion bits of information traveling down a single fiber. Intel researchers think they can scale the technology up to 10 GHz or faster in the future. A single photonic link can carry multiple, simultaneous data channels at the same speed by using different colors of light, just like multiple radio stations are transmitted to a car radio or hundreds of channels on a cable TV. Also, fiber optic cables are immune to electromagnetic interference and crosstalk, which makes traditional high-speed copper interconnects difficult to build.
Intel said it has a long-term research program in place to explore how to apply its silicon expertise in other areas, with a long-term goal of developing integrated optical devices.
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