Health monitoring of components operating at high temperatures requires the development of new sensors to measure temperature and deformation. A regenerated grating (RG) sensor with titanium (Ti)–silver (Ag)–nickel (Ni) multilayer coatings is fabricated by magnetron sputtering and electroplating processes. Optical and thermal tests are performed to evaluate the characteristics of the Ti–Ag–Ni-coated RG sensor. The shapes of the reflection spectra for the RG are slightly affected by the metallization process. The Ti–Ag–Ni-coated RG sensor exhibits a higher sensitivity than that of the bare RG for temperatures up to 600 ° C, with good repeatability and stability. It is verified that the titanium coating can achieve good adhesion to the optical fiber and that the silver coating is suitable as a conductive layer for electroplating. An analytical model for the axial strain and radial strain in a multilayer metal-coated optical fiber is proposed. Comparisons of the experimental results and the theoretical predictions show a good agreement below 250 ° C. These results indicate that multilayer metal-coated RG sensors can be successfully fabricated by combining magnetron sputtering with electroplating and provide great potential for high-temperature sensing.

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We have successfully fabricated regenerated gratings (RGs) with silver coating in standard telecommunication fibers by annealing and magnetron sputtering (MG) process. Optical testing showed that the optical properties of the silverrecoated RGs were slightly affected by MG process. We performed thermal tests to evaluate the characteristics with respect to a silver-recoated RG (SRCRG) sensor within the temperature of up to 600 o C. The experimental results showed that the SRCRG sensor exhibited a satisfactory performance for its sensitivity, repeatability and stability. Results from the experiments also revealed that the silver coating achieved good adhesion to fiber and could be used as a conductive layer for the further electroplating process.