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Proceedings Paper

High-sensitivity electro-optic CO2 gas sensing based on absorption spectroscopy
Author(s): Scott N. Zhang; Dorothy Y. Wang; Jianmin Gong; Dian Fan; Bo Dong; Michael Fraser; Anbo Wang
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Paper Abstract

We reported a high-sensitivity CO2 gas sensing system based on wavelength scanning absorption spectroscopy. A distributed feedback (DFB) laser was used as the light source in the system, whose wavelength was thermally tuned, by a thermoelectric cooler (TEC), to scan around one CO2 absorption line near 1572nm. Scanning of the absorption line spectrum is performed over a glass CO2 gas cell, 16.5 cm long with collimated optical fiber connectors. Different concentrations of CO2 were prepared by a high-precision gas flow control meter and sealed within the gas cell. A self-designed detection and amplification circuit was employed for absorption spectrum detection. The circuit implements background-cancellation with a two tier amplification scheme. By cancelling the high background signal, we can improve the CO2 sensitivity by about two orders of magnitude compared with commonly used direct detection methods with high background signals. Reducing the high DC signal permits isolated amplification of the absorption line spectrum. Absorption spectra of different CO2 concentrations were measured, and the results demonstrated sensing capability of 100% to <0.1% concentrations of CO2. This sensing system is expected to be used in conjunction with a wireless CO2 sensor network for large area CO2 monitoring. Given the very lower power consumption of the DFB laser and the detection circuit this sensing system offers a solution for affordable long term CO2 monitoring for reliable storage in carbon sequestration.

Paper Details

Date Published: 19 May 2012
PDF: 9 pages
Proc. SPIE 8376, Photonic Microdevices/Microstructures for Sensing IV, 83760G (19 May 2012); doi: 10.1117/12.920825
Show Author Affiliations
Scott N. Zhang, Virginia Polytechnic Institute and State Univ. (United States)
Dorothy Y. Wang, Virginia Polytechnic Institute and State Univ. (United States)
Jianmin Gong, Virginia Polytechnic Institute and State Univ. (United States)
Dian Fan, Wuhan Univ. of Technology (China)
Bo Dong, Virginia Polytechnic Institute and State Univ. (United States)
Michael Fraser, Virginia Polytechnic Institute and State Univ. (United States)
Anbo Wang, Virginia Polytechnic Institute and State Univ. (United States)


Published in SPIE Proceedings Vol. 8376:
Photonic Microdevices/Microstructures for Sensing IV
Xudong Fan; Hai Xiao; Anbo Wang, Editor(s)

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