Ppb-level mid-infrared ethane detection based on three measurement schemes using a 3.34-μm continuous-wave interband cascade laser
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- 作者：Chunguang Li ; Chuantao Zheng ; Lei Dong ; Weilin Ye ; Frank K. Tittel…
- 刊名：Applied Physics B: Lasers and Optics
- 出版年：2016
- 出版时间：July 2016
- 年：2016
- 卷：122
- 期：7
- 全文大小：1,596 KB
- 刊物类别：Physics and Astronomy
- 刊物主题：Physics
Electromagnetism, Optics and Lasers
Physical Chemistry
Laser Technology and Physics and Photonics
Quantum Optics, Quantum Electronics and Nonlinear Optics
Optical Spectroscopy and Ultrafast Optics
Physics and Applied Physics in Engineering - 出版者：Springer Berlin / Heidelberg
- ISSN：1432-0649
- 卷排序：122
文摘
A ppb-level mid-infrared ethane (C2H6) sensor was developed using a continuous-wave, thermoelectrically cooled, distributed feedback interband cascade laser emitting at 3.34 μm and a miniature dense patterned multipass gas cell with a 54.6-m optical path length. The performance of the sensor was investigated using two different techniques based on the tunable interband cascade laser: direct absorption spectroscopy (DAS) and second-harmonic wavelength modulation spectroscopy (2f-WMS). Three measurement schemes, DAS, WMS and quasi-simultaneous DAS and WMS, were realized based on the same optical sensor core. A detection limit of ~7.92 ppbv with a precision of ±30 ppbv for the separate DAS scheme with an averaging time of 1 s and a detection limit of ~1.19 ppbv with a precision of about ±4 ppbv for the separate WMS scheme with a 4-s averaging time were achieved. An Allan–Werle variance analysis indicated that the precisions can be further improved to 777 pptv @ 166 s for the separate DAS scheme and 269 pptv @ 108 s for the WMS scheme, respectively. For the quasi-simultaneous DAS and WMS scheme, both the 2f signal and the direct absorption signal were simultaneously extracted using a LabVIEW platform, and four C2H6 samples (0, 30, 60 and 90 ppbv with nitrogen as the balance gas) were used as the target gases to assess the sensor performance. A detailed comparison of the three measurement schemes is reported. Atmospheric C2H6 measurements on the Rice University campus and a field test at a compressed natural gas station in Houston, TX, were conducted to evaluate the performance of the sensor system as a robust and reliable field-deployable sensor system.