Tiny lasers used in new chemical detector

April 28, 2008 at 1:22 PM
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CAMBRIDGE, Mass., April 28 (UPI) -- U.S. scientists say they are developing an infrared laser spectrometer to do what canaries did for early miners -- warn of certain gases.

Harvard University scientist Federico Capasso and colleagues said their spectrometer could be just as powerful as the bulky instruments now used to detect gases, yet small enough to fit inside a shoe box.

Instead of using thermal sources for infrared rays, the researchers use a tiny array of 32 infrared quantum cascade lasers on a chip smaller than a dime. Each laser emits a distinct wavelength, together covering a broad spectral infrared range.

The scientists said their research marks the first time a laser spectrometer capable of such performance has been reported.

The advantage of using a laser source, they said, is that lasers are much brighter than thermal sources, thus providing a higher signal-to-noise ratio. The lasers can also be fine-tuned to provide wavelengths on demand -- akin to having thousands of canaries, each capable of detecting a range of chemicals.

The team that included student Benjamin Lee and postdoctoral fellow Mikhail Belkin will report its findings next month in San Jose, Calif., during the annual Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference.

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