LAUSR

Using a technique to observe reflection spectra, the signal-to-noise ratio can be improved for time-division multiplexed interrogation of three fiber Bragg gratings (FBGs) based on heterodyne detection methods. To calculate peak reflection wavelengths of the FBG reflections, absorption lines of 12 C 2 H 2 are used as wavelength markers, and temperature dependence of the peak wavelength is measured for one FBG. Positioning the FBGs at a distance of 20 km from the control port demonstrates the applicability of this method to a long sensor network.