We apply frequency-shifted interferometry to interrogate multiple gas sensors along a single fiber. This method uses a tunable continuous-wave laser and a slow detector, and allows spectral overlap of sensors. It can be used to quantify the concentrations of single or different gas species at multiple locations. A three-sensor system was used to demonstrate this capability, achieving a minimum detectable acetylene concentration of 230 ppm with a 3-cm gas cell, or equivalently, 6.9 ppm$\cdot$m. The design considerations in the implementation and the system parameters are also discussed.
© 2009 IEEE
Fei Ye, Li Qian, and Bing Qi, "Multipoint Chemical Gas Sensing Using Frequency-Shifted Interferometry," J. Lightwave Technol. 27, 5356-5364 (2009)