Study on temperature-dependent performance of polarization maintaining fiber used in all-fiber current transformer

In this paper, the mathematical relationship between temperature and extinction ratio of polarization-maintaining fiber is deduced by Jones matrix, and then the extinction ratio and output light intensity changes of bow-tie fiber and panda fiber, which are commonly used as polarization-maintaining delay fiber in FOCT, are measured by building an extinction ratio measurement system. At the temperature of
$-40^{\circ}\mathrm{C}-70^{\circ}\mathrm{C}$
, the extinction ratio of bow-tie fiber changed by 4.39dB, and the output light intensity changed by 16.4%, while the extinction ratio of panda fiber only changed by 1.1dB, and the output light intensity only changed by 3.34% at low temperature. At the same time, the relationship between extinction ratio and temperature of spun high-birefringence fibers used as sensing fiber ring in FOCT is also tested, which provides experimental support for error analysis of FOCT.