Cavity ringdown spectroscopy using mid-infrared quantum-cascade lasers

Paldus, Barbara A.; Harb, C. C.; Spence, Thomas G.; Zare, Richard N.; Gmachl, Claire F.; Capasso, Federico; Sivco, Deborah L.; Baillargeon, J. N.; Hutchinson, Albert L.; Cho, A. Y.

doi:10.1364/ol.25.000666

Cited by 114 publications

(59 citation statements)

References 12 publications

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“…46 A sensitivity of 9.7ϫ 10 −11 cm −1 Hz −1/2 , i.e., within an order of magnitude of the ultimate shot-noise-limit, was achieved with the application of QCLs to NICE-OHMS. 47 Focusing on potential field-deployable systems, Silva et al 8 reported a study which combined a thermoelectrically ͑TE͒ cooled pulsed QCL with CRDS and ICOS.…”

Section: Introductionmentioning

confidence: 87%

“…IV A 3 and is comparable to several other CEAS or ICOS studies exhibiting a NEA down to 4 ϫ 10 −8 cm −1 Hz −1/2 . 50,52,54,55,58 It is still almost a factor of ϳ50 less sensitive than CRDS employing a cw QCL as demonstrated by Paldus et al, 46 which may be explained by the commonly omitted cavity mode noise in CRDS. For CEAS or ICOS the minimum detectable absorption is typically lim- ited to 10 −2 -10 −3 due to incomplete averaging over the cavity resonances.…”

Section: System Performancementioning

confidence: 99%

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Trace gas measurements using optically resonant cavities and quantum cascade lasers operating at room temperature

Welzel

Lombardi

Davies

et al. 2008

Journal of Applied Physics

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Röpcke, J. (2008). Trace gas measurements using optically resonant cavities and quantum cascade lasers operating at room temperature. Journal of Applied Physics, 104(9), 093115-1/15. [093115]. DOI: 10.1063/1.3008014 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Achieving the high sensitivity necessary for trace gas detection in the midinfrared molecular fingerprint region generally requires long absorption path lengths. In addition, for wider application, especially for field measurements, compact and cryogen free spectrometers are definitely preferable. An alternative approach to conventional linear absorption spectroscopy employing multiple pass cells for achieving high sensitivity is to combine a high finesse cavity with thermoelectrically ͑TE͒ cooled quantum cascade lasers ͑QCLs͒ and detectors. We have investigated the sensitivity limits of an entirely TE cooled system equipped with an ϳ0.5 m long cavity having a small sample volume of 0.3 l. With this spectrometer cavity enhanced absorption spectroscopy employing a continuous wave QCL emitting at 7.66 m yielded path lengths of 1080 m and a noise equivalent absorption of 2 ϫ 10 −7 cm −1 Hz −1/2 . The molecular concentration detection limit with a 20 s integration time was found to be 6 ϫ 10 8 molecules/ cm 3 for N 2 O and 2 ϫ 10 9 molecules/ cm 3 for CH 4 , which is good enough for the selective measurement of trace atmospheric constituents at 2.2 mbar. The main limiting factor for achieving even higher sensitivity, such as that found for larger volume multi pass cell spectrometers, is the residual mode noise of the cavity. On the other hand the application of TE cooled pulsed QCLs for integrated cavity output spectroscopy and cavity ring-down spectroscopy ͑CRDS͒ was found to be limited by the intrinsic frequency chirp of the laser. Consequently the accuracy and advantage of an absolute internal absorption calibration, in theory inherent for CRDS experiments, are not achievable.

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Section: Introductionmentioning

confidence: 87%

Section: System Performancementioning

confidence: 99%

Trace gas measurements using optically resonant cavities and quantum cascade lasers operating at room temperature

Welzel

Lombardi

Davies

et al. 2008

Journal of Applied Physics

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“…If mirror reflectivity remains constant during experiments, change in ring-down time can be linked to increased absorption or scattering within the sample placed between the mirrors. CRDS has long been used to measure gas-phase absorbers [1][2][3] or aerosols [4][5][6][7][8] since optical losses due to scattering in the gas phase is minimal [9,10] and effective path lengths of kilometers can be achieved. In addition, since the measurement monitors the rate of light lost from the cell, the measurement is independent of spectroscopic source power fluctuations.…”

Section: Cavity Ring-down Spectroscopy (Crds)mentioning

confidence: 99%

Cavity-Enhanced Spectroscopy in Condensed Phases: Recent Literature and Remaining Challenges

Thompson

2017

Journal of Spectroscopy

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“…Cavity ringdown (CRD) is a sensitive optical spectroscopic technique which was introduced almost 20 years ago and which has been employed in numerous studies in various configurations and applications [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. In contrast to conventional optical absorption and transmission techniques, CRD is based on the time measurement of the exponential decay of the light intensity within a cavity formed by highly reflective dielectric mirrors.…”

Section: Cavity Ringdown Spectroscopymentioning

confidence: 99%

Near-infrared laser based cavity ringdown spectroscopy for applications in petrochemical industry

Vogler

Sigrist

2006

Appl. Phys. B

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A simple, economic diode laser based cavity ringdown system for trace-gas applications in the petrochemical industry is presented. As acetylene (C 2 H 2 ) is sometimes present as an interfering contaminant in the gas flow of ethylene (ethene, C 2 H 4 ) in a polyethylene production process, an on-line monitoring of such traces is essential. We investigated C 2 H 2 -C 2 H 4 mixtures in a gas-flow configuration in real time. The experimental setup consists of a near-infrared external cavity diode laser with an output power of a few mW, standard telecommunication fibers and a home-made gas cell providing a user-friendly cavity alignment. A noise-equivalent detection sensitivity of 4.5 × 10 −8 cm −1 Hz −1/2 was achieved, corresponding to a detection limit of 20 ppbV C 2 H 2 in synthetic air at 100 mbar. In an actual C 2 H 2 -C 2 H 4 gas-flow measurement the minimum detectable concentration of C 2 H 2 added to the C 2 H 4 gas stream (which may already contain an unknown C 2 H 2 contamination) increased to 160 ppbV. Moreover, stepwise C 2 H 2 concentration increments of 500 ppbV were resolved with a 1-min time resolution and an excellent linear relationship between the absorption coefficient and the concentration was found.

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Cavity ringdown spectroscopy using mid-infrared quantum-cascade lasers

Cited by 114 publications

References 12 publications

Trace gas measurements using optically resonant cavities and quantum cascade lasers operating at room temperature

Trace gas measurements using optically resonant cavities and quantum cascade lasers operating at room temperature

Cavity-Enhanced Spectroscopy in Condensed Phases: Recent Literature and Remaining Challenges

Near-infrared laser based cavity ringdown spectroscopy for applications in petrochemical industry

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