Photonic Crystal Fiber Temperature Sensor Based on Coupling Between Liquid-Core Mode and Defect Mode

Abstract

A high-sensitivity temperature sensor of compact photonic crystal fiber (PCF) based on the coupling between liquid-core mode and defect mode has been analyzed by the finite element method. The temperature sensitive materials with high refractive index (n = 1.65 at 25 °C), which support liquid-core modes, are filled into the central air hole of PCF. Six cores are formed by removing air holes in the second layer. The six cores work as defect modes and show high confinement losses. The liquid-core mode couples to defect mode as the phase matching condition is satisfied. The sensitivity and figure of merit reach -1.85 nm/°C, -0.072/°C and -1.95 nm/°C, -0.035/°C. The temperature sensor is competitive in the reported temperature sensors. The simple structure is easy to fabricate, and the structure can be further improved.