High-Sensitivity Temperature Sensor Based on Reflective Solc-Like Filter With Cascaded Polarization Maintaining Fibers

A high-sensitivity temperature sensor based on reflective Solc-like filter with Vernier effect has been proposed and experimentally investigated in this article. The reflective Solc-like filter is composed of a polarizer and the cascaded polarization maintaining fibers (PMFs) of similar length, which is a kind of all-fiber polarization interference filter. The gold film is coated in the end of the longer PMF to improve the reflectivity of the filter. The mathematical model of the reflective Solc-like filter has been built by the Jones matrix. The simulation results show that the main factor affecting the temperature sensitivity is the length of the PMF fiber, and the fringe visibility of the spectral fringes is only related to splice angles. Experiment results indicate that the Solc-like filter exhibits a high sensitivity of -44.27 nm/°C, which is enlarged over 25 times compared with that of the reflective Solc filter with single PMF, and the temperature resolution can reach 4.5×10
^{-4 °}
C. To the best of our knowledge, this is the first demonstration that the cascaded PMFs have been applied to the reflective filter, which provides high reference value for the application of polarization interference filters in the sensing field.