Disruptive fiber sensors

Abstract

The growing interest in optical fiber sensor is due to its unique advantages such as extremely low transmission loss, lightweight, small size, excellent durability, immunity to electromagnetic interference, high sensibility and large bandwidth etc. Particularly, photonic crystal fiber (PCF) is an excellent platform for constructing optical fiber sensor since the air holes running along the fiber length allows us to flexibly tune the optical characteristics of the PCF. This project aimed to explore an optical fiber temperature sensor with high sensitivity. The key idea of the proposed approach is to selectively fill liquid crystal into air holes around one silica core of a dual core photonic crystal fiber (DCPCF). 5CB (4-Cyano-4'-pentylbiphenyl) Nematic Liquid Crystal (NLC) was chosen for this project due to its high refractive index and good thermal tunability. Because of the large RI difference between 5CB and silica, photonic band gap and total internal reflection can possibly exist in the DCPCF at the same time, forming a PCF with hybrid guiding mechanism i.e. hybrid PCF. Because of the strong thermal-dependence of the refractive index of 5CB, the proposed hybrid PCF is supposed to have high temperature sensing capability. The fabrication method, the optical characteristics, the wavelength filtering properties and the temperature response of the hybrid PCF will be investigated in this project. Importantly, the fabrication of the hybrid PCF is the foundation of the further experimental demonstration. Thereby, the fabrication method is thoroughly explored at this stage. Besides, the spectrum characteristic of a fabricated hybrid PCF is experimentally analyzed in this report.