World's Highest-Power Mid-Infrared Semiconductor Lasers

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Donna Cunningham, 802-482-3748, [email protected]

Steve Eisenberg, 908-582-7474, [email protected]

BELL LABS SCIENTISTS REPORT WORLD'S HIGHEST-POWER MID-INFRARED SEMICONDUCTOR LASERS

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ATLANTA -- Scientists from Bell Labs, the research and development arm of Lucent Technologies, unveiled the world's highest-power mid-infrared semiconductor laser here today, at the 100th-anniversary meeting of the American Physical Society.

Researcher Claire Gmachl, of the Semiconductor Physics Research department, introduced a new, experimental quantum-cascade (QC) laser with more than a thousand times the output power of any commercial semiconductor laser operating in the mid-infrared wavelength region. Pulsed at room temperature, it produces about half a watt of power; in continuous-wave operation and cooled to about 100 degrees below zero Fahrenheit, it produces a full watt of laser light.

QC lasers operate like an electronic waterfall, with electrons cascading down an energy staircase, producing light pulses, or photons, as they hit each step along the way. Gmachl demonstrated that adding stages to QC lasers increases their output power. Electrons in the new laser cascade down 75 steps, instead of 20 or 30 as in earlier QC lasers.

The QC laser was invented five years ago by Federico Capasso and Jerome Faist at Bell Labs, and commercial applications are now being explored in areas like environmental sensing, pollution monitoring, combustion diagnostics, collision avoidance, radar, and medicine.

Gmachl, Bell Labs researcher Alessandro Tredicucci, and Edward Whittaker of Stevens Institute of Technology, in New Jersey, will each present an additional APS technical paper related to QC-laser technology.

A QC laser's wavelength is determined by several factors. In manufacture, varying the thicknesses of the material layers of the laser sets its wavelength, and adding a grating (etched material) on top of the laser makes the wavelength more precise. In use, adjusting the temperature or the electrical current applied to the laser changes its wavelength.

QC lasers are grown by molecular beam epitaxy (MBE), a crystal-growth technology developed in the 1960s by Alfred Cho, director of the Bell Labs Semiconductor Research Lab, which involves "spray painting" atoms to build new materials one atomic layer at a time.

They are among numerous laser innovations from Bell Labs, where 41 years ago Arthur Schawlow and Charles Townes invented the laser -- one of the century's greatest inventions. Semiconductor lasers are now the most widely used and versatile class of lasers.

Lucent Technologies, headquartered in Murray Hill, N.J., designs, builds and delivers a wide range of public and private networks, communications systems and software, consumer and business telephone systems and microelectronics components. Further information is available at http://www.lucent.com.

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