We present photoacoustic (PA) spectroscopy measurements of carbon dioxide, methanol, and ammonia. The light source for the excitation was a single-mode quantum cascade distributed-feedback laser, which was operated in pulsed mode at moderate duty cycle and slightly below room temperature. Temperature tuning resulted in a typical wavelength range of 3cm<sup>-1</sup>at a linewidth of 0.2cm<sup>-1</sup>. The setup was based on a Herriott multipass arrangement around the PA cell; the cell was equipped with a radial 16-microphone array to increase sensitivity. Despite the relatively small average laser power, the ammonia detection limit was 300 parts in 10<sup>9</sup>by volume.
© 2001 Optical Society of America
(140.0140) Lasers and laser optics : Lasers and laser optics
(140.3070) Lasers and laser optics : Infrared and far-infrared lasers
(140.3490) Lasers and laser optics : Lasers, distributed-feedback
(140.5960) Lasers and laser optics : Semiconductor lasers
(300.6430) Spectroscopy : Spectroscopy, photothermal
Daniel Hofstetter, Mattias Beck, Jérôme Faist, Markus Nägele, and Markus W. Sigrist, "Photoacoustic spectroscopy with quantum cascade distributed-feedback lasers," Opt. Lett. 26, 887-889 (2001)