High Temperature Sensor Based on Tapered Few Modes All-Solid Photonic Bandgap Fiber

In this paper, the tapered photonic crystal fiber (PCF) temperature sensor was analyzed using eigenmode expansion method. The tapered PCF temperature sensor was designed based on singlemode-multimode-singlemode (SMS) structure. The multimode section consists of a large-core all-solid photonic bandgap fiber (AS-PBF) with silica as the background material and germanium-doped silica at the high index core region. The length is calculated with the formula of the linear thermal expansion coefficient and the refractive index changed is based on the temperature dependent Sellmier equation. The modes were computed using finite element method (FEM) and the propagation was analyzed using finite element-eigenmode expansion method (FE-EME). The numerical results indicate that the tapered PCF temperature sensor can function in a wide range of temperature that is from T= 20 degrees C to T= 930 degrees C and operating at wavelength of visible red-light sensor between 620nm - 660nm. The sensitivity is shown to be 4.7 pm/degrees C.