Off-axis integrated-cavity-output spectroscopy for trace-gas concentration measurements: modeling and performance

We present a detailed study of the properties of off-axis-aligned high-finesse optical cavities under output time integration for spectroscopic applications. The dependence of the characteristics of the sample absorption spectra on a number of experimental parameters is investigated by developing a general model, where a Voigt absorption line shape is included into the cavity-transfer function. In this way, we address the issue of the measurement of trace amounts of gases in ambient air and single out the optimum conditions to give accurate estimates of the gas mixing ratio by the extraction of the integrated absorbance of the spectra. Quantitative results by the model are displayed for the detection of natural-abundance methane at 3 μm as a function of the air-sample total pressure. Finally, we compare the model predictions with the results of a previous experiment, evidencing their consistency.

[1]  Daniel Halmer,et al.  Parts per trillion sensitivity for ethane in air with an optical parametric oscillator cavity leak-out spectrometer. , 2004, Optics letters.

[2]  Motoichi Ohtsu,et al.  Highly sensitive detection of molecular absorption using a high finesse optical cavity , 1994 .

[3]  P. De Natale,et al.  A 3.5-mW continuous-wave difference-frequency source around 3 μm for sub-Doppler molecular spectroscopy , 2005, EQEC '05. European Quantum Electronics Conference, 2005..

[4]  D. Tedesco,et al.  First field determination of the 13C/12C isotope ratio in volcanic CO2 by diode-laser. , 2004, Optics express.

[5]  Jun Ye,et al.  Ultrasensitive detections in atomic and molecular physics: demonstration in molecular overtone spectroscopy , 1998 .

[6]  T. L. Thompson,et al.  A fast-response near-infrared tunable diode laser absorption spectrometer for in situ measurements of CH4 in the upper troposphere and lower stratosphere , 2002 .

[7]  J G Anderson,et al.  Ultrasensitive absorption spectroscopy with a high-finesse optical cavity and off-axis alignment. , 2001, Applied optics.

[8]  D. Romanini,et al.  CW cavity ring down spectroscopy , 1997 .

[9]  P. Hering,et al.  Isotopic ratio measurement of methane in ambient air using mid-infrared cavity leak-out spectroscopy , 2001 .

[10]  Skip Williams,et al.  Quantitative detection of singlet O2 by cavity-enhanced absorption. , 2004, Optics letters.

[11]  A. Cho,et al.  Spectroscopic detection of biological NO with a quantum cascade laser , 2001, Applied physics. B, Lasers and optics.

[12]  J. B. Paul,et al.  Sensitive absorption measurements in the near-infrared region using off-axis integrated-cavity-output spectroscopy , 2002 .

[13]  Michael E. Webber,et al.  Diode-laser absorption measurements of CO2, H2O, N2O, and NH3 near 2.0 μm , 1998 .

[14]  P De Natale,et al.  Combining a difference-frequency source with an off-axis high-finesse cavity for trace-gas monitoring around 3 microm. , 2006, Optics express.

[15]  Rudy Peeters,et al.  Open-path trace gas detection of ammonia based on cavity-enhanced absorption spectroscopy , 2000 .

[16]  Herwig Kogelnik,et al.  Off-Axis Paths in Spherical Mirror Interferometers , 1964 .

[17]  V. L. Kasyutich,et al.  Off-axis continuous-wave cavity-enhanced absorption spectroscopy of narrow-band and broadband absorbers using red diode lasers , 2002 .

[18]  David I. Rosen,et al.  Integrated cavity output spectroscopy measurements of NO levels in breath with a pulsed room-temperature QCL , 2005 .

[19]  Frank K. Tittel,et al.  Sub-ppbv nitric oxide concentration measurements using cw thermoelectrically cooled quantum cascade laser-based integrated cavity output spectroscopy , 2006 .

[20]  Frank K Tittel,et al.  Mid-infrared quantum cascade laser based off-axis integrated cavity output spectroscopy for biogenic nitric oxide detection. , 2004, Applied optics.