Diminishing Dimensions; The Solid-State Century; Scientific American Presents; by Corcoran,Zorpette; 8 Page(s)

In a tiny, cluttered room at Bell Laboratories, a division of Lucent Technologies in Murray Hill, N.J., researcher Jerome Faist is standing in front of an optical bench. In his right hand, near one of the lenses on the bench, he is holding a piece of paper torn from a desk calendar. In the middle of the bench, white puffs of water vapor pour from a cryostat, within which a revolutionary new type of laser known as a quantum cascade is being cooled with liquid helium.

With his left thumb, Faist taps a button on an instrument, boosting the voltage being applied to the semiconductor laser housed in the cryostat. Bright pinpoints of light on the piece of paper and wisps of smoke indicate that we have ignition. "If you need more convincing, you can put your finger in there," says a grinning Federico Capasso, with whom Faist invented the laser.