Temperature sensing based on photonic crystal fiber filled with thermo-optic liquids of ethanol-toluene mixed solution

In this paper, a temperature sensor based on photonic crystal fiber (PCF) is designed and proposed. The temperature sensing is realized by filling different concentration ratios thermo-optic liquids of Ethanol-Toluene in the innermost layer six airholes of the PCF, which is consisting of a solid core and five layers air holes of hexagonal lattices. The propagation characteristics of proposed sensor have been investigated by adopting the full vectorial-finite element method (FV-FEM). The relationship between effective refractive index (neff), effective mode area (Aeff), confinement loss (Lc) and temperature have been numerically simulated. Simulation results show that both neff and Aeff are decreased with the increasing of temperature for a constant wavelength. The confinement loss peak occurs uniform red-shifted when the temperature rises, which indicate a linear relation between the wavelength of the loss peak and temperature of thermo-optic liquids. Furthermore, the working temperature range of the sensor can be adjusted by mixing different ratios of the thermo-optic liquids, the temperature sensitivity is as high as 6 nm/°C. The new sensor can also be produced at a low cost and provides a new avenue for ultrasensitive temperature sensing.