Heterodyne detection for fiber Bragg grating sensors

In this paper, we present a Fiber-Bragg-Grating-based temperature sensor. T he technique employs heterodyne detection using two Fiber Bragg Gratings. O ne of the gratings is used as a reference (local oscillator) and the second as a sensing arm. This sensor uses a Folded Mach-Zehnder interferometer. A s the temperature changes, the Bragg wavelength of the FBG shifts. The hete rodyne detection is used to detect the frequency difference between the ref erence and sensing signals that is caused by the temperature change. The dy namic range and sensitivity of the sensor were analyzed and presented. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.