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Effective utilization of quantum-cascade distributed-feedback lasers in absorption spectroscopy

2000; Optica Publishing Group; Volume: 39; Issue: 24 Linguagem: Inglês

10.1364/ao.39.004425

0003-6935

Anatoliy A. Kosterev, R. F. Curl, Frank K. Tittel, Claire Gmachl, Federico Capasso, Deborah L. Sivco, James N. Baillargeon, Albert L. Hutchinson, Alfred Y. Cho,

Laser Design and Applications

A variable duty cycle quasi-cw frequency scanning technique was applied to reduce thermal effects resulting from the high heat dissipation of type I quantum-cascade lasers. This technique was combined with a 100-m path-length multipass cell and a zero-air background-subtraction technique to enhance detection sensitivity to a parts-in-109 (ppb) concentration level for spectroscopic trace-gas detection of CH4, N2O, H2O, and C2H5OH in ambient air at 7.9 µm. A new technique for analysis of dense high-resolution absorption spectra was applied to detection of ethanol in ambient air, yielding a 125-ppb detection limit.