Liquid-Crystal-Filled Side-hole Fiber for High-Sensitivity Temperature and Electric Field Measurement

We propose a highly sensitive sensor based on a nematic liquid-crystal-filled side-hole fiber. The liquid crystal is precisely filled into an air hole of the optical fiber using a method of manually gluing in the fusion splicer. Due to the coupling between the liquid crystal waveguide and the fiber core, multiple response dips appear in the transmission spectrum of the device. When an external temperature or electric field variation is applied to the liquid crystal and its refractive index changes, the transmission spectrum of this device will shift accordingly. Temperature and electric field response tests were performed on the device in the experiment, and the obtained temperature and electric field sensitivities were as high as -1.5 nm/°C and 3.88 nm/V_pp, respectively. For the exhibited advantages of being easy to manufacture, low cost, and high sensitivity, the proposed sensor is very promising for actual application in temperature or weak electric field monitoring.