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.

Date Published: 29 April 2016
PDF: 8 pages
Proc. SPIE 9899, Optical Sensing and Detection IV, 98992E (29 April 2016); doi: 10.1117/12.2227749

Published in SPIE Proceedings Vol. 9899:
Optical Sensing and Detection IV
Francis Berghmans; Anna G. Mignani, Editor(s)