Applications of fiber Bragg grating sensors and high-speed interrogation techniques

摘要

We are developing several kinds of fiber Bragg grating (FBG) sensors for application in river surveillance monitoring, civil structural monitoring, aerospace health monitoring, and so on. In this paper we describe highly precise FBG sensing systems, specifically water-level sensors, as a practical example. We have achieved sensor accuracy of ± 0.1% F.S., i.e. ± 1 cm for a full measurement range of 10m in water level. For other applications, FBG interrogation techniques are described for high-frequency vibration monitoring or acoustic emission detection. In this FBG interrogation system, optical filters based on planar lightwave circuit (PLC) technology are used to measure the wavelength of the reflected light from each FBG sensor. We discuss two types of the optical filter, a Mach-Zehnder interferometer (MZI) and an arrayed waveguide grating (AWG). The wavelength shift of the FBG sensor due to strain or temperature change is determined through direct detection of the light intensity ratio from the output ports of the optical filter. We have made a FBG interrogation unit which allows four-channel FBGs to be connected in series to measure strain in the x, y, and z directions as well as temperature. Copyright © 2005 John Wiley & Sons, Ltd.