Enhanced Temperature Sensitivity by Nickel–Copper-Coated Optical Fiber in Distributed Sensing Based on Rayleigh Scattering

In this paper, the temperature and relative humidity (RH) response of a nickel–copper-coated (Ni-Cu-coated) optical fiber was investigated using a Rayleigh-based optical frequency-domain reflectometer (OFDR). The temperature sensitivity of the Ni-Cu-coated optical fiber was determined experimentally as −2.50 GHz/°C, which is significantly higher than that of standard single-mode optical fibers. Measurements performed under controlled RH conditions reveal that the Ni-Cu-coated optical fiber has negligible response to RH. The Ni-Cu-coated optical fiber could be used for distributed temperature sensing in Rayleigh-based OFDR setups with high spatial resolution in environments with varying RH conditions.