Research on D-Shape Open-Loop PCF Temperature Refractive Index Sensor Based on SPR Effect

PCF (Photonic crystal fiber) temperature refractive index sensor based on SPR effect with the new double membrane open-loop structure is proposed. The inner surface of such PCF’s open-loop structure is plated with a layer of 70 nm gold film, and a layer of 20 nm SiO $_{2}$ film is coated on the gold film, which could effectively prevent the gold film from oxidation corrosion. Besides, the open loop could reduce the production cost, and it could form two energy channels with nearby air holes, promoting the leakage of core energy to plasma mode and enhancing the SPR effects. The ethanol could be adopted as the temperature sensing solution, to measure the refractive index sensing of the solution to be measured. Numerical simulation is carried out based on the full vector finite element method, and the simulation results indicate that the average wavelength sensitivity of refractive index sensing could reach 3330 nm/RIU, and the wavelength sensitivity of temperature sensing could reach 0.912 nm/$^{\circ }$ C, and a maximum figure of merit (FOM) of 102 which is approximately four times larger than that of the similar reported PCF-SPR sensors in the literature. The simulation results show that D-shape open-loop photonic crystal fiber has the potential application prospect on the temperature and refractive index sensing.