Submitted to SPIE Optics East Conferences: Infrared to terahertz technologies for health and the environment (LS102), Boston October 23-26, 2005

Room-Temperature Continuous-Wave Quantum Cascade Laser based Nitric Oxide Measurements using Integrated Cavity Output Spectroscopy

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]

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.

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.
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.
References
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)
. 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).

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

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.