<p>Submitted to SPIE Optics East Conferences: Infrared to terahertz technologies for health and the environment (LS102), Boston October 23-26, 2005</p><p>Room-Temperature Continuous-Wave Quantum Cascade Laser based Nitric Oxide Measurements using Integrated Cavity Output Spectroscopy</p><p>Yury A. Bakhirkin, and Frank K. Tittel Rice Quantum Institute, MS 366, Rice University, 6100 Main St., Houston, TX 77005, USA Phone: (713) 348 2757, Fax: (713) 348 5686, [email protected]</p><p>S. Blaser, D. A. Yarekha, M Giovannini, Jerome Faist Institute of Physics, Universite de Neuchâtel, Rue A.L. Breguet 1, 2000 Neuchâtel, Switzerland PRESENTATION PREFERENCE: Oral Presentation.</p><p>The development of compact laser based sensors for nitric oxide (NO) detection is of interest for a number of applications, such as environmental monitoring and medical diagnostics. The recent realization of continuous-wave (CW), distributed feedback (DFB) quantum cascade lasers (QCL), which can operate at thermoelectrically cooled temperatures [1], has made it possible to avoid the use of a liquid nitrogen cryostat. <BR> This talk will focus on the demonstration of a trace gas sensor based on a room temperature CW DFB QCL and off-axis integrated cavity output spectroscopy (OA-ICOS) [2] with wavelength modulation to measure NO concentrations at ppbv levels. For this work, a CW DFB QCL with a spectral tuning range from 1827 cm-1 (+200C) to 1838 cm-1 (-320C) was used. Specifically a NO absorption line P(11.5) at 1835.57 cm-1 (5.45 m) was selected. A QCL output power of  2 mW for the P(11.5) line was obtained at a temperature of (–210C) and a laser current of  750 mA. A sample cell, 50 cm in length with a volume of  500 cm3, is used. The second harmonic (2f) signal of the OA-ICOS cavity output was sampled with a lock-in amplifier and averaged using a data acquisition card and LabView software. A detection limit of  1.3 ppbv in 1 second, based on a SNR = 1, was obtained. Further improvement of the SNR and detection limit will be discussed. <BR> References <BR> 1. S. Blaser, D. A. Yarekha, L. Hvozdara, Y. Bonetti, A. Muller, M. Giovannini, and J. Faist, “Room temperature, continuous-wave single-mode quantum-cascade lasers at  ~ 5.4 microns”, Appl. Phys. Lett. 86, 41109 (2005) <BR>. 2. Yu. A. Bakhirkin, A. A. Kosterev, C. Roller, R. F. Curl, and F.K. Tittel, Mid-Infrared Quantum Cascade Laser based Off-Axis Integrated Cavity Output Spectroscopy for Biogenic NO Detection, Applied Optics 43, 2257-2266 (2004).<BR></p><p>KEYWORDS: room temperature quantum cascade laser, integrated cavity output spectroscopy, wavelength modulation, Submitted to SPIE Optics East Conferences: Infrared to terahertz technologies for health and the environment (LS102), Boston October 23-26, 2005</p><p>PRINCIPAL AUTHOR'S BIOGRAPHY: Yury A. Bakhirkin graduated with honor from Moscow State Engineering Physics Institute in 1985. M.D. in Physics (major – Solid State Physics). 1999 – PhD in Physics and Mathematics (Russian Academy of Science). From January 2002 to present time – postdoctoral fellow at Rice University, Houston, Texas, USA.</p>