Continuous wave, distributed feedback diode laser based sensor for trace-gas detection of ethane

The development of a continuous wave (CW), thermoelectrically cooled (TEC), distributed feedback (DFB) laser diode based spectroscopic trace-gas sensor for ultrasensitive and selective ethane (C2H6) concentration measurements is reported. The sensor platform used tunable diode laser absorption spectroscopy (TDLAS) based on a 2f wavelength modulation (WM) detection technique. TDLAS was performed with a 100 m optical path length astigmatic Herriott cell. For an interference free C2H6 absorption line located at 2976.8 cm−1 a 1σ minimum detection limit of 240 pptv (part per trillion by volume) with a 1 second lockin amplifier time constant was achieved. In addition, reliable and long-term sensor performance was obtained when operating the sensor in an absorption line locked mode. K. Krzempek Laser & Fiber Electronics Group, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland R. Lewicki · F.K. Tittel ( ) Department of Electrical and Computer Engineering, Rice University, 6100 Main Street, Houston, TX 77251, USA e-mail: [email protected] Fax: +1-713-3485686 L. Nähle · M. Fischer · J. Koeth Nanoplus GmbH Oberer, Kirschberg 4, 97218 Gerbrunn, Germany S. Belahsene · Y. Rouillard Institut d’Electronique du Sud, UMR 5214 CNRS, Université Montpellier 2, 34095 Montpellier, France L. Worschech Technische Physik, University of Würzburg, Am Hubland, 97074 Würzburg, Germany