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PTB Industry News |
March 29, 1999 | ||||||
Bell Labs Introduces World's Highest-Power | |||||||
ATLANTA, Mar. 22 -- Scientists from Bell Labs, the R&D division of Lucent Technologies, have introduced the world's highest-power mid-infrared semiconductor laser, at the 100th-anniversary meeting of the American Physical Society. Researcher Claire Gmachl, of the Semiconductor Physics Research department, demonstrated an experimental quantum-cascade (QC) laser with more than a thousand times the output of any commercial semiconductor laser operating in the mid-infrared wavelength region. Pulsed at room temperature, the laser produces about half a watt of power. In continuous-wave operation, cooled to about 100 degrees below zero Fahrenheit, it produces a full watt of laser light. QC lasers have been likened to an electronic waterfall, with electrons cascading down an "energy staircase," producing photons as they hit each step. Gmachl showed that adding stages to QC lasers increases their output power. Electrons in the new laser cascade down 75 steps, rather than the 20 or 30 of previous QC lasers. The QC laser was invented five years ago by Federico Capasso and Jerome Faist of Bell Labs. According to Lucent, commercial applications are being explored in environmental sensing, pollution monitoring, combustion diagnostics, collision avoidance, radar, and medicine. Researchers say that a QC laser's wavelength is determined by several factors. In manufacture, varying the thickness of the material layers of the laser sets its wavelength; 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. The process involves "spray painting"
atoms to build new materials one atomic layer at a time. PTB Home |