We report the first application of a thermoelectrically cooled, distributed-feedback quantum-cascade laser for continuous spectroscopic monitoring of CO in ambient air at a wavelength of 4.6 μm. A noise-equivalent detection limit of 12 parts per billion was demonstrated experimentally with a 102-cm optical pathlength and a 2.5-min data acquisition time at a 10-kHz pulsed-laser repetition rate. This sensitivity corresponds to a standard error in fractional absorbance of 3 × 10<sup>−5</sup>.
© 2002 Optical Society of America
Anatoliy A. Kosterev, Frank K. Tittel, Rüdeger Köhler, Claire Gmachl, Federico Capasso, Deborah L. Sivco, Alfred Y. Cho, Shawn Wehe, and Mark G. Allen, "Thermoelectrically Cooled Quantum-Cascade-Laser-Based Sensor for the Continuous Monitoring of Ambient Atmospheric Carbon Monoxide," Appl. Opt. 41, 1169-1173 (2002)