Fabrication and thermal characteristics of multilayer metal-coated regenerated grating sensors for high-temperature sensing

摘要

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.