PHOTONIC FRONTIERS: QUANTUM CASCADE LASERS: Quantum cascade lasers prepare to compete for terahertz applications

摘要

Rapid improvements in quantum cascade lasers are making them important sources in the mid-infrared... and promising new sources in the terahertz range. Users like Sheng Wu of the Power, Environmental, and Research Institute (Covina, CA) can testify to the dramatic progress in quantum cascade lasers (QCLs). When Wu bought his first in late 2005, driving the laser required a 7 A, 15 V pulse, yet he wondered if he was seeing blackbody emission rather than laser output. Just two years ago, a proposal reviewer scoffed at his idea of replacing "a cheap and reliable 10 W blackbody source used in every spectrometer" with a QCL emitting less than 10 mW "which might not even work continuously, barely tunes 1percent of the infrared (IR), yet costs 100 times more." Now Wu is using mid-IR QCL spectroscopy to analyze carbon-isotope ratios in hydrocarbons.