Optical feedback frequency stabilized cavity ring-down spectroscopy

Burkart, Johannes; Romanini, D.; Kassi, S.

doi:10.1364/ol.39.004695

Cited by 49 publications

(36 citation statements)

References 20 publications

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“…As a result, very low noise photodetectors are required to achieve high signal-to-noise ratios on the ring-down decay events. In addition, high efficiency electro-optic modulators are not available in the mid-infrared, which can make Pound-Drever-Hall locking [11] far more challenging [12] as well as precluding the use of recently developed frequency-agile techniques [6, 7, 13]. …”

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Ultra-sensitive cavity ring-down spectroscopy in the mid-infrared spectral region

et al. 2016

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We describe an ultra-sensitive cavity ring-down spectrometer which operates in the mid-infrared spectral region near 4.5 µm. With this instrument a noise-equivalent absorption coefficient of 2.6×10−11 cm−1 Hz−1/2 was demonstrated with less than 150 nW of optical power incident on the photodetector. Quantum noise was observed in the individual ring-down decay events, leading to quantum-noise-limited short-time performance. We believe that this spectrometer’s combination of high sensitivity and robustness make it well suited for measurements of ultra-trace gas species as well as applications in optics and fundamental physics.

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“…2. To the best of our knowledge this the first mid-infrared instrument, and only the third overall [7–9], which exhibited quantum noise in the ring-down decay events in a traditional (i.e. direct current) CRDS instrument.…”

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Ultra-sensitive cavity ring-down spectroscopy in the mid-infrared spectral region

et al. 2016

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“…Harnessing the combination of absorption sensitivity, frequency resolution, and light intensity offered by this optical feedback frequency-stabilized cavity ring-down spectrometer (OFFS-CRDS), 14 we measured Doppler-free Lamb dips on CO 2 lines with line strengths down to 5 × 10 −25 cm/molecule, among the weakest ever studied by saturation spectroscopy. By referencing the spectrometer to an optical frequency comb, we used these narrow saturated-absorption features to determine absolute transition frequencies with an accuracy of a few kHz.…”

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Communication: Saturated CO2 absorption near 1.6 μm for kilohertz-accuracy transition frequencies

Burkart

Sala

Romanini

et al. 2015

The Journal of Chemical Physics

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Doppler-free saturated-absorption Lamb dips were measured on weak rovibrational lines of (12)C(16)O2 between 6189 and 6215 cm(-1) at sub-Pa pressures using optical feedback frequency stabilized cavity ring-down spectroscopy. By referencing the laser source to an optical frequency comb, transition frequencies for ten lines of the 30013←00001 band P-branch and two lines of the 31113←01101 hot band R-branch were determined with an accuracy of a few parts in 10(11). Involving rotational quantum numbers up to 42, the data were used for improving the upper level spectroscopic constants. These results provide a highly accurate reference frequency grid over the spectral interval from 1599 to 1616 nm.

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“…Using a high-finesse cavity implies the need to bring a narrow cavity mode into coincidence with the laser frequency, which results in a time-consuming cavity-length adjustment if a high number of spectral points are targeted to achieve an accurate modeling of the absorption profile and correspondingly reduce systematic deviations. We solved this trade-off by combining a dither-based locking of the cavity to the laser with a fast and agile scanning of the laser through an optical single-sideband modulator (SSM) [14,15]. The piezo-dithering is performed at 500 Hz over ± 8.3 MHz and ensures a 1-kHz ring-down (RD) rate.…”

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Cavity-ring-down Doppler-broadening primary thermometry

et al. 2018

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A step forward in Doppler-broadening thermometry is demonstrated using a comb-assisted cavity-ring-down spectroscopic approach applied to an isolated near-infrared line of carbon dioxide at thermodynamic equilibrium. Specifically, the line-shape of the P e (12) line of the (30012) ← (00001) band of CO 2 at 1.578 µm is accurately measured and its Doppler width extracted from a refined multispectrum fitting procedure accounting for the speed dependence of the relaxation rates, which were found to play a role even at the very low pressures explored, from 1 to 7 Pa. The thermodynamic gas temperature is retrieved with relative uncertainties of 8 × 10 −6 (type A) and 11 × 10 −6 (type B), which ranks the system at the first place among optical methods. Thanks to a measurement time of only ≈5 h, the technique represents a promising pathway toward the optical determination of the thermodynamic temperature with a global uncertainty at the 10 −6 level.DOI: 10.1103/PhysRevA.97.012512The forthcoming redefinition of the unit kelvin [1], in 2018, in terms of a fixed value of the Boltzmann constant, prompts the interest for primary thermometers that are capable to operate over a relatively large part of the temperature scale with very high accuracy. Among primary methods, important advancements [2] have been obtained over the past decade on dielectric constant gas thermometry and Johnson noise thermometry [3,4]. After a first successful experiment of Doppler-broadening thermometry (DBT) [5], followed by significant improvements [6,7], the international community of fundamental metrology recognized the importance of an optical method that links the thermodynamic temperature to an optical frequency, as an independent confirmation of other primary approaches.DBT consists of retrieving the Doppler width ν D from the highly accurate observation of the shape of a given atomic or molecular line, in a laser-based absorption-spectroscopy experiment under a linear regime of radiation-matter interaction [8]. Once ν D is measured, if the central frequency (ν 0 ) and the atomic or molecular mass (M) are known, the inversion of the well-known equationallows one to determine the thermal energy and, consequently, either the gas temperature (T ) or the Boltzmann constant (k B ). So far, the most accurate implementation of DBT has been performed on a rovibrational transition of a water isotopologue at 1.39 µm. Using a dual-laser spectrometer and adopting a very sophisticated spectral analysis procedure, the Boltzmann constant could be determined with a combined uncertainty of 24 parts per million (ppm) [6,9,10].The history of DBT [11] shows that the major hurdle for a low-uncertainty determination of the Doppler width and hence of the thermal energy is the choice of the line-shape model adopted for the spectral analysis. Since a fully ab initio lineshape calculation is prohibitively complex for self-colliding molecules, a model suitable for being implemented into a fitting routine requires approximations and simplifications. At the same time, th...

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Optical feedback frequency stabilized cavity ring-down spectroscopy

Cited by 49 publications

References 20 publications

Ultra-sensitive cavity ring-down spectroscopy in the mid-infrared spectral region

Ultra-sensitive cavity ring-down spectroscopy in the mid-infrared spectral region

Communication: Saturated CO2 absorption near 1.6 μm for kilohertz-accuracy transition frequencies

Cavity-ring-down Doppler-broadening primary thermometry

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