Fiber Bragg grating-based wavelength modulation spectroscopy technique for trace gas sensing
TL;DR: In this article, a tunable fiber Bragg grating (FBG) and a super luminescent light emitting diode (SLED) source is proposed for trace gas sensing.
Abstract: A novel gas sensing system based on a tunable fiber Bragg grating (FBG) and a Super luminescent light emitting diode (SLED) source is proposed for trace gas sensing. Such a system has been demonstrated for precise detection of acetylene (C2H2) using wavelength modulation spectroscopy technique (WMS) based on modulating the Bragg wavelength of FBG within the width of an absorption line of a target gas. The sensing system has been calibrated against specific gas concentrations (ppm) through controlled experiments and the minimum detectable acetylene (C2H2) gas concentration is experimentally found to be ~ 80 ppm (0.008% by volume). Furthermore, the detection limit of the system is estimated to be limited by the noise floor of our system at ~ 7 ppm (0.0007% by volume). The proposed system provides a relatively inexpensive alternative for trace gas sensing based on a well-established FBG technology. Moreover, the proposed system has tremendous potential for simultaneous detection of multiple species through the use of a cascaded set of carefully chosen FBGs.
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TL;DR: This paper demonstrates, for the first time to the best knowledge, the application of a tunable external-cavity fiber Bragg grating diode laser in spectroscopic chemical sensing.
Abstract: This paper demonstrates, for the first time to our best knowledge, the application of a tunable external-cavity fiber Bragg grating diode laser in spectroscopic chemical sensing. A tunable fiber Bragg grating external-cavity semiconductor laser is demonstrated with over 10 nm of tuning range. A piezoactuator was implemented to stretch the grating for rapid wavelength tuning of the laser. The application of such low-cost tunable FBG lasers in spectroscopic chemical sensing was demonstrated in acetylene gas with a wavelength modulation spectroscopy technique.
15 citations
"Fiber Bragg grating-based wavelengt..." refers background in this paper
...e about the width of a gas absorption line [7] ....
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...The occurrence of two dips at output per cycle of input sinusoid occurs because the absorption wavelength of the target gas specie coincides with the Bragg wavelength of FBG twice during the time periods “T” of the input sinusoidal signal [7,8] ....
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TL;DR: In this paper, a low-cost and high-precision gas sensor for the concentration measurement of acetylene gas, in which a broadband source combined with a fiber Bragg grating (FBG) was used as the wavelength modulated device and wavelength modulation spectroscopy (WMS) was adopted for signal processing.
2 citations
"Fiber Bragg grating-based wavelengt..." refers methods in this paper
...Broad band sources coupled with FBGs, using wavelength modulation spectroscopy have also been demonstrated previously with an ASE source and cantilever beam based FBG tuning [5,6] ....
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13 Dec 2014
TL;DR: An easy-realizable gas sensing system using absorption type optical fiber is studied and discussed, in order to improve the detection sensitivity and anti-interference ability of popular acetylene gas sensor.
Abstract: An easy-realizable gas sensing system using absorption type optical fiber is studied and discussed, in order to improve the detection sensitivity and anti-interference ability of popular acetylene gas sensor. Using ASE as light source, the detection sensitivity has been greatly improved. Wavelength modulation on ASE broadband light source using fiber Bragg grating and PZT to obtain narrowband reflected output light. At the same time, using a combined structure of differential detection and harmonic detection, eliminates the influence of light source power fluctuation, the absorption coefficient change with the environment and other factors on the measurement results, and effectively improves the sensitivity and the anti-interference ability of the system.
1 citations
"Fiber Bragg grating-based wavelengt..." refers methods in this paper
...Broad band sources coupled with FBGs, using wavelength modulation spectroscopy have also been demonstrated previously with an ASE source and cantilever beam based FBG tuning [5,6] ....
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