Application of Balanced Detection to Absorption Measurements of Trace Gases with Room-Temperature, Quasi-cw Quantum-Cascade Lasers.

Distributed-feedback quantum-cascade (QC) lasers are expected to form the heart of the next-generation mid-IR laser absorption spectrometers, especially as they are applied to measurements of trace gases in a variety of environments. The incorporation of room-temperature-operable, single-mode QC lasers should result in highly compact and rugged sensors for real-world applications. We report preliminary results on the performance of a laser absorption spectrometer that uses a QC laser operating at room temperature in a quasi-cw mode in conjunction with balanced ratiometric detection. We have demonstrated sensitivities for N(2)O [10 parts in 10(6) volume-mixing ratio for a 1-m path (ppmv-m)] and NO [520 parts in 10(9) volume-mixing ratio for a 1-m path (ppbv-m)] at 5.4 mum. System improvements are described that are expected to result in a 2 orders of magnitude increase in sensitivity.

[1]  Philip C. D. Hobbs,et al.  Double-beam laser absorption spectroscopy: shot noise-limited performance at baseband with a novel electronic noise canceler , 1991, Photonics West - Lasers and Applications in Science and Engineering.

[2]  A. Tredicucci,et al.  Improved CW operation of quantum cascade lasers with epitaxial-side heat-sinking , 1999, IEEE Photonics Technology Letters.

[3]  Laurence S. Rothman,et al.  Reprint of: The HITRAN molecular spectroscopic database and HAWKS (HITRAN Atmospheric Workstation): 1996 edition , 1998 .

[4]  M. Loewenstein,et al.  Airborne tunable diode laser spectrometer for trace-gas measurement in the lower stratosphere. , 1993, Applied optics.

[5]  A. Cho,et al.  Methane concentration and isotopic composition measurements with a mid-infrared quantum-cascade laser. , 1999, Optics letters.

[6]  M. Allen,et al.  Ultrasensitive, visible tunable diode laser detection of NO(2). , 1996, Applied optics.

[7]  Four-laser airborne infrared spectrometer for atmospheric trace gas measurements. , 1996, Applied optics.

[8]  Glen W. Sachse,et al.  Fast‐response, high‐precision carbon monoxide sensor using a tunable diode laser absorption technique , 1987 .

[9]  P C Hobbs,et al.  Ultrasensitive laser measurements without tears. , 1997, Applied optics.

[10]  W. Rawlins,et al.  Characteristics of O(I) and N(I) resonance line broadening in low pressure helium discharge lamps , 1977 .

[11]  J. Drummond,et al.  Laboratory, ground-based, and airborne tunable diode laser systems: performance characteristics and applications in atmospheric studies , 1998 .

[12]  R. May,et al.  Aircraft (ER-2) laser infrared absorption spectrometer (ALIAS) for in-situ stratospheric measurements of HCI, N(2)O, CH(4), NO(2), and HNO(3). , 1994, Applied optics.

[13]  A. Cho,et al.  Sensitive absorption spectroscopy with a room-temperature distributed-feedback quantum-cascade laser. , 1998, Optics letters.

[14]  C. Gmachl,et al.  Complex-coupled quantum cascade distributed-feedback laser , 1997, IEEE Photonics Technology Letters.

[15]  R. Zare,et al.  Photoacoustic spectroscopy using quantum-cascade lasers. , 1999, Optics letters.

[16]  W. Kessler,et al.  In-situ sensing of tropospheric water vapor using an airborne near-IR diode laser hygrometer , 1998 .

[17]  J. A. Silver,et al.  Near‐infrared diode laser airborne hygrometer , 1994 .

[18]  Harold I. Schiff,et al.  A tunable diode laser system for aircraft measurements of trace gases , 1990 .

[19]  R. Grisar,et al.  TRISTAR – a tracer in situ TDLAS for atmospheric research , 1998 .

[20]  Frank K. Tittel,et al.  Compact laser difference-frequency spectrometer for multicomponent trace gas detection , 1998 .

[21]  A. Cho,et al.  High-resolution (Doppler-limited) spectroscopy using quantum-cascade distributed-feedback lasers. , 1998, Optics letters.

[22]  W. Kessler,et al.  Ultrasensitive dual-beam absorption and gain spectroscopy: applications for near-infrared and visible diode laser sensors. , 1995, Applied optics.