Optical cavity enhanced real-time absorption spectroscopy of CO2 using laser amplitude modulation

We present a spectrometer based on the cavity enhanced amplitude modulated laser absorption spectroscopy (CEAMLAS) technique for measuring molecular gas absorption. This CEAMLAS spectrometer accurately measured a CO2 absorption line at 1572.992 nm with effectively 100% measurement duty cycle. It achieved an absorption sensitivity of 5.2 × 10−9 Hz−1∕2 using a linear Fabry-Perot cavity with a modest finesse of ≈1000. We also used the spectrometer to perform preliminary measurements of the 13C/12C isotopic ratio in CO2, yielding an isotopic signature δ13C of −83±9‰ for our CO2 sample.

[1]  J. Hodges,et al.  Frequency-agile, rapid scanning spectroscopy: absorption sensitivity of 2 × 10−12 cm−1 Hz−1/2 with a tunable diode laser , 2014 .

[2]  J. Chow,et al.  Ultrasensitive real-time measurement of dissipation and dispersion in a whispering-gallery mode microresonator. , 2013, Optics letters.

[3]  D. McClelland,et al.  Critical coupling control of a microresonator by laser amplitude modulation. , 2012, Optics express.

[4]  D. McClelland,et al.  Experimental demonstration of impedance match locking and control for coupled resonators. , 2010, Optics express.

[5]  A. Foltynowicz,et al.  Noise-immune cavity-enhanced optical heterodyne molecular spectroscopy: Current status and future potential , 2008 .

[6]  E. Crosson,et al.  A cavity ring-down analyzer for measuring atmospheric levels of methane, carbon dioxide, and water vapor , 2008 .

[7]  D. McClelland,et al.  Using active resonator impedance matching for shot-noise limited, cavity enhanced amplitude modulated laser absorption spectroscopy. , 2008, Optics express.

[8]  L. Fay,et al.  Liquid chromatography combined with mass spectrometry for 13C isotopic analysis in life science research. , 2007, Mass spectrometry reviews.

[9]  B. Orr,et al.  Detection of trace gases by rapidly-swept continuous-wave cavity ringdown spectroscopy: pushing the limits of sensitivity , 2006 .

[10]  L. Avois,et al.  Testosterone and doping control , 2006, British Journal of Sports Medicine.

[11]  Dudley E. Shallcross,et al.  Trace detection of methane using continuous wave cavity ring-down spectroscopy at 1.65 μm , 2002 .

[12]  Richard N Zare,et al.  Stable isotope ratios using cavity ring-down spectroscopy: determination of 13C/12C for carbon dioxide in human breath. , 2002, Analytical chemistry.

[13]  Charles C. Harb,et al.  A laser-locked cavity ring-down spectrometer employing an analog detection scheme , 2000 .

[14]  Jun Ye,et al.  Ultrasensitive frequency-modulation spectroscopy enhanced by a high-finesse optical cavity: theory and application to overtone transitions of C 2 H 2 and C 2 HD , 1999 .

[15]  M. Becchi,et al.  Gas chromatography/combustion/isotope-ratio mass spectrometry analysis of urinary steroids to detect misuse of testosterone in sport. , 1994, Rapid communications in mass spectrometry : RCM.

[16]  A. O’Keefe,et al.  Cavity ring‐down optical spectrometer for absorption measurements using pulsed laser sources , 1988 .

[17]  John L. Hall,et al.  Laser phase and frequency stabilization using an optical resonator , 1983 .