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Switching to a laser record.

A year ago, Lester F. Eastman and his collaborators at Cornell University surprised the scientific community by reporting that they had built a laser that could turn on and off 15 billion times a second (15 gigahertz). Using a tiny, newly designed and fabricated "strained quantum well" laser, the Cornell scientists have now pushed the rate up to a breathtaking 28 gigahertz, the fastest ever for any laser. Theorists had doubted that quantum well lasers would ever approach such rates.

The Cornell laser consists of several extremely thin layers of indium gallium arsenide separated by gallium arsenide barriers. These layers -- no more than 40 atoms thick -- serve as quantum wells, which confine electrons within their boundaries. The laser appears to owe its superior switching rate to the presence of indium atoms, which distort, or strain, the orderly gallium arsenide crystal structure.
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Publication:Science News
Date:Jan 11, 1992
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