Optical time-domain reflectometry for distributed sensing of the structural strain and deformation

The period of in-fiber grating can be changed due lo the change of pressure or temperature that the in-liber grating bears. The reflecting wavelength of in-liber grating will shift as its period changes. This characteristic trait of in-fiber grating can render it to be used as a sensor element to detect pressure or temperature. The key issue is how to interrogate the reflecting wavelength shift accurately. The techniques of in-fiber grating sensors are reviewed with an emphasis on interrogation approaches to reflecting wavelength shift induced by measurement quantities. Some suggestions are also made m this paper. Published by Hisevier Science Ltd. All rights reserved.