Cavity ring down spectroscopy with 5 × 10(-13) cm-1 sensitivity.

The ultimate sensitivity performances obtained with a continuous wave-cavity ring down spectroscopy setup in the near infrared are investigated. At fixed frequency, the noise of the photodetector is found to be the main limitation and the best limit of detection (about 10(-11) cm(-1)) is reached after a 10 s averaging. We show that long term baseline fluctuations can be efficiently averaged over several days allowing us to reach a detection limit as low as 5 × 10(-13) cm(-1). The achieved sensitivity is illustrated on narrow spectral intervals where the weakest lines detected so far by absorption spectroscopy are observed: (i) ultra-weak transitions of the a(1)Δ(g)(0)-X (3)Σ(g) (-)(1) hot band of (16)O(2) near 1.58 μm and (ii) first detection of an electric quadrupole transition in the second overtone band of nitrogen ((14)N(2)) near 1.44 μm.

[1]  J. Komasa,et al.  The absorption spectrum of D2: ultrasensitive cavity ring down spectroscopy of the (2-0) band near 1.7 μm and accurate ab initio line list up to 24,000 cm(-1). , 2012, The Journal of chemical physics.

[2]  J. Hodges,et al.  Frequency-stabilized single-mode cavity ring-down apparatus for high-resolution absorption spectroscopy , 2004 .

[3]  B. Bussery-Honvault,et al.  Very high sensitivity CW-cavity ring down spectroscopy: Application to the a1Δg(0)–X3Σg-(1) O2 band near 1.58 μm , 2005 .

[4]  Coupled-cavity ring-down spectroscopy technique. , 2012, Optics letters.

[5]  K. Lehmann,et al.  Effects of linear birefringence and polarization-dependent loss of supermirrors in cavity ring-down spectroscopy. , 2008, Applied optics.

[6]  J. Hodges,et al.  High-signal-to-noise-ratio laser technique for accurate measurements of spectral line parameters , 2012 .

[7]  S. Mikhailenko,et al.  The absorption spectrum of water in the 1.25 μm transparency window (7408–7920 cm−1) , 2011 .

[8]  K. Lehmann,et al.  Long-term stability in continuous wave cavity ringdown spectroscopy experiments. , 2010, Applied optics.

[9]  C. Radzewicz,et al.  Cavity ring-down spectroscopy of the oxygen B-band with absolute frequency reference to the optical frequency comb. , 2012, The Journal of chemical physics.

[10]  D. W. Allan,et al.  Statistics of atomic frequency standards , 1966 .

[11]  Hui Li,et al.  Quadrupole moment function and absolute infrared quadrupolar intensities for N2. , 2007, The Journal of chemical physics.

[12]  D. Mondelain,et al.  The high sensitivity absorption spectrum of ozone (18O3 and 16O3) near 7800 cm−1: Identification of the 3A2(0 0 0)–X(1 1 0) hot band superimposed to very weak vibrational bands , 2011 .

[13]  Kevin K. Lehmann,et al.  Ring-down cavity absorption spectroscopy of the very weak HCN overtone bands with six, seven, and eight stretching quanta , 1993 .

[14]  Noise in cavity ring-down spectroscopy caused by transverse mode coupling. , 2007, Optics express.

[15]  D. Mondelain,et al.  The 1.28 μm transparency window of methane (7541-7919 cm⁻¹): empirical line lists and temperature dependence (80 K-300 K). , 2011, Physical chemistry chemical physics : PCCP.

[16]  H. Pickett,et al.  Laboratory measurements and theoretical calculations of O_2 A band electric quadrupole transitions , 2009 .

[17]  J. Komasa,et al.  The absorption spectrum of H2: CRDS measurements of the (2-0) band, review of the literature data and accurate ab initio line list up to 35000 cm(-1). , 2012, Physical chemistry chemical physics : PCCP.

[18]  Peter F. Bernath,et al.  On the line parameters for the X 1sigma+g (1–0) infrared quadrupolar transitions of 14N2 , 2007 .

[19]  High sensitivity CW-cavity ring down spectroscopy of 12CO2 near 1.35 μm (II): New observations and line intensities modeling , 2010 .