scholarly journals Optical feedback linear cavity enhanced absorption spectroscopy

2021 ◽  
Author(s):  
Gang Zhao ◽  
Jianfei Tian ◽  
Weiguang Ma ◽  
Adam Fleisher ◽  
Suotang Jia
Keyword(s):  
Absorption Spectroscopy ◽  
Optical Feedback ◽  
Linear Cavity ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy

Near-infrared optical-feedback linear cavity-enhanced absorption spectroscopy

2021 ◽  
Vol 29 (5) ◽  
pp. 933-939
Author(s):  
Fei XU ◽  
◽  
Xiao-bin ZHOU ◽  
Zheng-bo LIU ◽  
Gang ZHAO ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Near Infrared ◽  
Optical Feedback ◽  
Linear Cavity ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy

scholarly journals Comparison of optical-feedback cavity-enhanced absorption spectroscopy and gas chromatography for ground-based and airborne measurements of atmospheric CO concentration

2017 ◽  
Vol 10 (5) ◽  
pp. 1803-1812 ◽  
Author(s):  
Irène Ventrillard ◽  
Irène Xueref-Remy ◽  
Martina Schmidt ◽  
Camille Yver Kwok ◽  
Xavier Faïn ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
High Performance ◽  
Optical Feedback ◽  
Mercuric Oxide ◽  
Gas Chromatograph ◽  
Laser Spectrometer ◽  
Airborne Measurements ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
Compact Size

Abstract. We present the first comparison of carbon monoxide (CO) measurements performed with a portable laser spectrometer that exploits the optical-feedback cavity-enhanced absorption spectroscopy (OF-CEAS) technique, against a high-performance automated gas chromatograph (GC) with a mercuric oxide reduction gas detector (RGD). First, measurements of atmospheric CO mole fraction were continuously collected in a Paris (France) suburb over 1 week. Both instruments showed an excellent agreement within typically 2 ppb (part per billion in volume), fulfilling the World Meteorological Organization (WMO) recommendation for CO inter-laboratory comparison. The compact size and robustness of the OF-CEAS instrument allowed its operation aboard a small aircraft employed for routine tropospheric air analysis over the French Orléans forest area. Direct OF-CEAS real-time CO measurements in tropospheric air were then compared with later analysis of flask samples by the gas chromatograph. Again, a very good agreement was observed. This work establishes that the OF-CEAS laser spectrometer can run unattended at a very high level of sensitivity ( <  1 ppb) and stability without any periodic calibration.

scholarly journals Application of Near-Infrared Optical Feedback Cavity Enhanced Absorption Spectroscopy (OF-CEAS) to the Detection of Ammonia in Exhaled Human Breath

Sensors ◽  
2019 ◽  
Vol 19 (17) ◽  
pp. 3686
Author(s):  
Zhifu Luo ◽  
Zhongqi Tan ◽  
Xingwu Long
Keyword(s):  
Detection Limit ◽  
Absorption Spectroscopy ◽  
Spectral Resolution ◽  
Optical Feedback ◽  
Low Pressure ◽  
High Spectral Resolution ◽  
Trace Gas ◽  
Human Breath ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy

The qualitative and quantitative analysis to trace gas in exhaled human breath has become a promising technique in biomedical applications such as disease diagnosis and health status monitoring. This paper describes an application of a high spectral resolution optical feedback cavity enhanced absorption spectroscopy (OF-CEAS) for ammonia detection in exhaled human breath, and the main interference of gases such as CO2 and H2O are approximately eliminated at the same time. With appropriate optical feedback, a fibered distributed feedback (DFB) diode laser emitting at 1531.6 nm is locked to the resonance of a V-shaped cavity with a free spectral range (FSR) of 300 MHz and a finesse of 14,610. A minimum detectable absorption coefficient of αmin = 2.3 × 10−9 cm−1 is achieved in a single scan within 5 s, yielding a detection limit of 17 ppb for NH3 in breath gas at low pressure, and this stable system allows the detection limit down to 4.5 ppb when the spectra to be averaged over 16 laser scans. Different from typical CEAS with a static cavity, which is limited by the FSR in frequency space, the attainable spectral resolution of our experimental setup can be up to 0.002 cm−1 owing to the simultaneous laser frequency tuning and cavity dither. Hence, the absorption line profile is more accurate, which is most suitable for low-pressure trace gas detection. This work has great potential for accurate selectivity and high sensitivity applications in human breath analysis and atmosphere sciences.

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