Shedding New Light on Silicon Switches

Though silicon appears opaque to the naked eye, it is transparent to infrared light, the same wavelength typically used for optical communications. Researchers with Intel Corp., Santa Clara, Calif., have used this property of silicon to build a novel “transistorlike” device that encodes electronic data onto light beams.

Here’s how it works: A single light beam splits into two as it passes through the silicon. The transistorlike device then hits one of the beams with an electric charge, triggering a phase shift. When the two beams recombine, the phase shift induced between them causes light exiting the chip to switch on and off at over 1 GHz, 50-times faster than conventional silicon circuits. Switching speeds of 10 GHz or faster are possible, say researchers. This on-and-off pattern of light can be translated into the 1′s and 0′s needed to transmit data.

The ability to build fast, photonic modulators from standard silicon could lead to low-cost, high-bandwidth fiber-optic connections among PCs, servers, and other electronic devices, and eventually inside computers as well. A single photonic link can carry multiple, simultaneous data channels at the same speed using different colors of light. Unlike conventional high-speed copper interconnects, fiber optics are immune to electromagnetic interference and cross talk.

Copyright Penton Media, Inc. Apr 15, 2004