Prism-based Broadband Optical Cavity (400 – 1600 nm) for High-Sensitivity Trace Gas Sensing by Cavity Enhanced Absorption Spectroscopy

2020 ◽  
Author(s):  
Weidong Chen ◽  
Gaoxuan Wang ◽  
Lingshuo Meng ◽  
Qian Gou ◽  
Azer Yalin ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Gas Sensing ◽  
Optical Cavity ◽  
Wavelength Region ◽  
High Sensitivity ◽  
Central Wavelength ◽  
Enhanced Absorption ◽  
High Reflectivity ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
High Finesse

<p>The use of high reflectivity dielectric mirrors to form a high finesse optical cavity allows one to achieve long optical path lengths of up to several kilometres for high-sensitivity spectroscopy applications [1]. However, the high reflectivity of a dielectric mirror is achieved via constructive interference of the Fresnel reflection at the interfaces produced by multilayer coatings of alternate high and low refractive index materials. This wavelength-dependent coating limits the bandwidth of the mirror's high reflectivity to only a few percent of the designed central wavelength [2].</p><p>In this paper, we report on the development of a novel optical cavity based on prism used as cavity reflector through total internal reflection combined with Brewster angle incidence [3], which offers a high-finesse optical cavity operating in a broadband wavelength region from 400 to longer than 1600 nm. Cavity Enhanced Absorption Spectroscopy (CEAS) of NO<sub>2</sub>, NO<sub>3</sub>, and H<sub>2</sub>O vapor was applied to determine the achieved prism reflectivity over a broad spectral range from 400 nm to 1600 nm.</p><p>Experimental details and preliminary results will be presented. The developed prism-based cavity is specifically adapted for the needs of broadband measurement of multi-molecular absorber or/and wavelength-dependent extinction coefficient of aerosols over a broad spectral region.</p><p>Acknowledgments. This work is supported by the French national research agency (ANR) under the CaPPA (ANR-10-LABX-005), the MABCaM (ANR-16-CE04-0009) and the MULTIPAS (ANR-16-CE04-0012) contracts. The authors thank the financial support from the CPER CLIMIBIO program.</p><p>REFERENCES</p><p>[1] S. S. Brown, "Absorption spectroscopy in high-finesse cavities for atmospheric studies", Chem. Rev. <strong>103</strong> (2003) 5219-5238.</p><p>[2] G.R. Fowles, Introduction to Modern Optics, 2nd ed. (Rinehart and Winston, 1975), p. 328.</p><p>[3] B. Lee, K. Lehmann, J. Taylor and A. Yalin, "A high-finesse broadband optical cavity using calcium fluoride prism retroreflectors", Opt. Express <strong>2</strong><strong>2</strong> (2014) 11583-11591.</p>

scholarly journals Implementation of an incoherent broadband cavity-enhanced absorption spectroscopy technique in an atmospheric simulation chamber for in situ NO<sub>3</sub> monitoring: characterization and validation for kinetic studies

2020 ◽  
Vol 13 (11) ◽  
pp. 6311-6323 ◽  
Author(s):  
Axel Fouqueau ◽  
Manuela Cirtog ◽  
Mathieu Cazaunau ◽  
Edouard Pangui ◽  
Pascal Zapf ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Rate Constants ◽  
Optical Cavity ◽  
In Situ Monitoring ◽  
Effective Length ◽  
Integration Time ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
Simulation Chamber

Abstract. An incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) technique has been developed for the in situ monitoring of NO3 radicals at the parts per trillion level in the CSA simulation chamber (at LISA). The technique couples an incoherent broadband light source centered at 662 nm with a high-finesse optical cavity made of two highly reflecting mirrors. The optical cavity which has an effective length of 82 cm allows for up to 3 km of effective absorption and a high sensitivity for NO3 detection (up to 6 ppt for an integration time of 10 s). This technique also allows for NO2 monitoring (up to 9 ppb for an integration time of 10 s). Here, we present the experimental setup as well as tests for its characterization and validation. The validation tests include an intercomparison with another independent technique (Fourier-transform infrared, FTIR) and the absolute rate determination for the reaction trans-2-butene + NO3, which is already well documented in the literature. The value of (4.13 ± 0.45) × 10−13 cm3 molecule−1 s−1 has been found, which is in good agreement with previous determinations. From these experiments, optimal operation conditions are proposed. The technique is now fully operational and can be used to determine rate constants for fast reactions involving complex volatile organic compounds (VOCs; with rate constants up to 10−10 cm3 molecule−1 s−1).

Signal processing system in cavity enhanced spectroscopy

2008 ◽  
Vol 16 (4) ◽  
Author(s):  
J. Wojtas ◽  
Z. Bielecki
Keyword(s):  
Signal Processing ◽  
Absorption Spectroscopy ◽  
Decay Time ◽  
Optical Cavity ◽  
Processing System ◽  
Signal Processing System ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
Useful Signal ◽  
No2 Sensor

AbstractThe paper presents a signal processing system used for nitrogen dioxide detection employing cavity enhanced absorption spectroscopy. In this system, the absorbing gas concentration is determined by the measurement of a decay time of a light pulse trapped in a cavity.The setup includes a resonance optical cavity, which was equipped with spherical and high reflectance mirrors, the pulsed diode laser (414 nm) and electronic signal processing system. In order to ensure registration of low-level signals and accurate decay time measurements, special preamplifier and digital signal processing circuit were developed.Theoretical analyses of main parameters of optical cavity and signal processing system were presented and especially signal-to-noise ratio was taken into consideration. Furthermore, investigation of S/N signal processing system and influence of preamplifier feedback resistance on the useful signal distortion were described.The aim of the experiment was to study potential application of cavity enhanced absorption spectroscopy for construction of fully optoelectronic NO2 sensor which could replace, e.g., commonly used chemical detectors. Thanks to the developed signal processing system, detection limit of NO2 sensor reaches the value of 0.2 ppb (absorption coefficient equivalent = 2.8 × 10−9 cm−1).

scholarly journals Simultaneous detection of C<sub>2</sub>H<sub>6</sub>, CH<sub>4</sub>, and <i>δ</i><sup>13</sup>C-CH<sub>4</sub> using optical feedback cavity-enhanced absorption spectroscopy in the mid-infrared region: towards application for dissolved gas measurements

2019 ◽  
Vol 12 (6) ◽  
pp. 3101-3109 ◽  
Author(s):  
Loic Lechevallier ◽  
Roberto Grilli ◽  
Erik Kerstel ◽  
Daniele Romanini ◽  
Jérôme Chappellaz
Keyword(s):  
Absorption Spectroscopy ◽  
Optical Feedback ◽  
Optical Cavity ◽  
Simultaneous Detection ◽  
Infrared Region ◽  
Integration Time ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
Interband Cascade Laser ◽  
Gas Measurements

Abstract. Simultaneous measurement of C2H6 and CH4 concentrations, and of the δ13C-CH4 isotope ratio is demonstrated using a cavity-enhanced absorption spectroscopy technique in the mid-IR region. The spectrometer is compact and has been designed for field operation. It relies on optical-feedback-assisted injection of 3.3 µm radiation from an interband cascade laser (ICL) into a V-shaped high-finesse optical cavity. A minimum absorption coefficient of 2.8×10-9 cm−1 is obtained in a single scan (0.1 s) over 0.7 cm−1. Precisions of 3 ppbv, 11 ppbv, and 0.08 ‰ for C2H6, CH4, and δ13C-CH4, respectively, are achieved after 400 s of integration time. Laboratory calibrations and tests of performance are reported here. They show the potential for the spectrometer to be embedded in a sensor probe for in situ measurements in ocean waters, which could have important applications for the understanding of the source and fate of hydrocarbons from the seabed and in the water column.

scholarly journals Review of Incoherent Broadband Cavity-Enhanced Absorption Spectroscopy (IBBCEAS) for Gas Sensing

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3646 ◽  
Author(s):  
Kaiyuan Zheng ◽  
Chuantao Zheng ◽  
Yu Zhang ◽  
Yiding Wang ◽  
Frank Tittel
Keyword(s):  
Absorption Spectroscopy ◽  
Recent Progress ◽  
Gas Sensing ◽  
Field Measurements ◽  
System Structure ◽  
Gas Detection ◽  
Detection Scheme ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
Potential Applications

Incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) is of importance for gas detection in environmental monitoring. This review summarizes the unique properties, development and recent progress of the IBBCEAS technique. Principle of IBBCEAS for gas sensing is described, and the development of IBBCEAS from the perspective of system structure is elaborated, including light source, cavity and detection scheme. Performances of the reported IBBCEAS sensor system in laboratory and field measurements are reported. Potential applications of this technique are discussed.

scholarly journals Study of a periodic spectral fluctuation existing in a fibered optical feedback cavity-enhanced absorption spectroscopy (OF-CEAS)

2019 ◽  
Vol 15 (1) ◽  
Author(s):  
Zhifu Luo ◽  
Zhongqi Tan ◽  
Xingwu Long
Keyword(s):  
Absorption Spectroscopy ◽  
Optical Feedback ◽  
Resonant Cavity ◽  
High Sensitivity ◽  
Trace Gas ◽  
Ripple Effect ◽  
Interference Theory ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
Theoretical Analyses

Abstract A special periodic spectral fluctuation is observed during the study of a fibered high sensitivity optical feedback cavity-enhanced absorption spectroscopy (OF-CEAS) for the measurement of trace gas. This spectral fluctuation is different from some phenomenon observed in former OF-CEAS which contain a resonant cavity with V-shaped configuration, such as the etalon effect and the spectral ripple effect. To reveal why this phenomenon happens and how it works, a series of hypothesis are proposed and tested, and the results show that the multi-beam interference of resonance light at the input mirror of the resonant cavity is the main reason for this phenomenon. Based on the multi-beam interference theory, a mathematical modeling of this phenomenon is built, and the theoretical analyses agree well with the experimental results. Some methods to eliminate this phenomenon are proposed and implemented, and the 1σ noise equivalent absorption coefficient of 7.6 × 10− 10 cm− 1 Hz-1/2 is attained with this robust and compact OF-CEAS system.

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