Mechanical reliability of fiber Bragg gratings for strain or temperature sensor

Abstract

Several factors influencing the mechanical strength of fiber Bragg grating (FBG) sensors during their fabrication were examined and FBG sensors were made with sufficiently strong mechanical strength. A chemical stripping technique to remove the acrylate coating of the fiber and H2 loading treatment to increase the photosensitivity showed negligible impact to the mechanical strength of fiber optic sensor. Therefore, these approaches were adopted for the discrimination of other factors pertaining to UV exposure. UV laser beam width exposed on the fiber was controlled up to 60μm so as to reduce damaged areas induced from laser exposure. Also the pulse fluence and the total dose of a pulsed KrF excimer laser were varied in order to investigate their influence on the mechanical strength. Finally FBG sensors with different reflectivity were fabricated with only slight strength degradation such that they could be used in a composite structure.