Wavelength Interrogation System for Quasi-Distributed Fiber Bragg Grating Temperature Sensors Based on a 50-GHz Array Waveguide Grating

We present a fiber Bragg grating (FBG) interrogation system equipped with a 50-GHz, 96-channel array waveguide grating (AWG), which was developed for temperature measurement. We have studied the linearity of the FBG-AWG system, in which the Bragg wavelength of one FBG was shifted over several AWG channels. We investigated the dependence of the linearity both on the FBG bandwidth and on the spectrum restoring algorithm. Packaging of FBG using epoxy-resin was tested in the range of −25 °C ~ 85 °C in order to increase the temperature sensitivity. A standard deviation error of 7 pm or 0.2 °C was obtained for 0.3 nm bandwidth epoxy-packaged FBG.