Investigating the effect of material on the coupling of guided wave in the optical fiber

The remote bonding configuration allows the application of FBG sensors in extreme environments. But as the length of the fiber increases the attenuation in the fiber becomes significant and the signal-to-noise ratio (SNR) is reduced. The amplitude of wave energy coupled in the fiber depends on the type and quality of the bond, the materials in contact as well as the attenuation of the wave in the fiber. In this paper, FBG sensors with different coatings are used and the amplitude of the wave coupled is studied in each of the cases. Four different material coatings including acrylate, polyimide, aluminium coated and PEEK-coated FBGs are used for the purpose.