Top Speed.
Intel's new silicon modulator can encode the equivalent of 8000 digital photos into a laser beam every second.

Computing at Light Speed

Staff Writer

Researchers at Intel have created the fastest-ever silicon-based optical modulator, a device that chops a laser beam into a series of pulses, creating the optical version of digital 1s and 0s. By the middle of the next decade, the new device could help designers create computers in which optical links connect dozens of chips, raising the machines' capabilities to dizzying new heights.

Many computers sold today already sport two or more central processors linked by copper wires that allow them to communicate electronically. Chip companies envision computers with tens to hundreds of processors working side by side. But copper wires can't handle all the electrical signals needed for such an architecture. Optical connections that transmit digital 1s and 0s as streams of light pulses can carry many times the load.

The devices needed to do the job are already in widespread commercial use for long-distance communications. But today they are built from exotic materials that are too costly for personal computers. Intel and other companies have been working to create similar gizmos out of silicon, the industry's standard material for computer chips. In 2004, for example, a team led by Mario Paniccia, an Intel photonics engineer in Santa Clara, California, created a silicon modulator that operates at 1 gigabit per second (Gb/s). In 2005, they pushed the power-hungry unit to 10 Gb/s. To reach higher speeds, Paniccia's group redesigned their modulator to be far more efficient. The new device, which they describe in this week's online version of Optics Express, can switch on and off at a blinding 30 Gb/s.

"This 30 Gb/s modulator makes silicon a real candidate for applications and is a big step forward for silicon photonics," says Graham Reed, an electrical engineer at the University of Surrey in the U.K. Paniccia says that relatively minor tweaks should allow his group to boost the speed of their modulator to 40 Gb/s. If so, he says, in about 10 years, engineers will be able to integrate the modulator with other devices to make optical links between nearby chips that can transfer a blistering trillion bits of data every second.

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