Silicon goes optical

Specialized components that send and receive light signals across optical fibers are usually made from exotic crystals or semiconductor materials that are expensive and hard to work with. Now, researchers have unveiled a component that can do this light work but is made of silicon, the workhorse material of microelectronics. Because chip makers are already masters at handling silicon and the material is cheap, the advance could lead to inexpensive circuits that process light, scientists say.

Whereas photonic circuits today are generally too costly except for heavily trafficked, long-distance telecommunications channels, the advent of silicon-based photonic devices might open many new uses, says Mario Paniccia of Intel Corp. in Santa Clara, Calif. In the Feb. 12 Nature, he and his Intel colleagues in Santa Clara and in Jerusalem report making a prototype silicon modulator that changes a laser beam’s intensity in order to signal the 1s and 0s of digital information (SN: 4/8/00, p. 231: Available to subscribers at Microdevice weds electronics, light fibers).

The modulator’s switching speed is fast enough to generate more than a billion data bits per second, which is 50 times as fast as any previous silicon-based modulator. That’s not as rapid as standard photonic components made from more expensive materials, but the Intel workers say they expect to boost the new modulator’s speed by up to tenfold.

“A low-cost silicon optical superchip could soon be a reality,” says Graham T. Reed of the University of Surrey in England in a commentary in the journal carrying the new report.

Superfast optical links between computers in local networks or between circuit boards inside the same computer could become practical, says Paniccia. However, photonic circuits that go completely silicon—including a silicon laser—aren’t likely any time soon, he notes.

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