A silicon nanobeam uses optical force to do mechanical work in an integrated circuit.By Katherine Bourzac
Since the 1980s, researchers have used lasers to stop molecular vibrations, so that the molecules can be observed in their natural environment. Now researchers at Yale University have used the same kind of nanoscale optical force to control an integrated circuit. Their device could form the basis of fast, low-power optical chips, just as transistors are the building blocks of today's electronic circuits. The new device, a light-driven nanoresonator, could also be used as an extremely sensitive chemical detector. The work is a major landmark in uniting mechanical and optical forces at the nanoscale.
Chips that use light instead of electrons to carry data should be faster and consume less power than traditional integrated circuits. But so far even the fastest optical chips have incorporated electrical elements called modulators. These modulators encode light with data by converting the signal from light into electrons and back again. This extra step makes optical chips complex and drains power. A circuit developed by Yale researchers led by electrical-engineering professor Hong Tang incorporates a modulator that's driven by light, not electrons.
The Yale group began its work by creating a silicon optical chip. To make the modulator, they etched a small portion of the waveguide, the thin silicon road along which the photons travel, into a 500-nanometer-wide bar. This silicon beam, which is suspended from the chip's surface so that it can flex, has two functions. It both carries the optical signal and modulates it. Tang and his colleagues sent a light signal through the integrated circuit, then shone laser light onto the nano-optical modulator, causing it to oscillate up and down. These oscillations modulate the speed of the light traveling through the beam....
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