采用全矢量有限元法,研究了空气孔为正九边形周期性排列的全内反射型光子晶体光纤的温度传感特性, 分析了不同空气孔排列形状、占空比以及波长对温度特性的影响,并与正六边形结构的光子晶体光纤进行了对比。研究表明, 空气孔为正九边形周期性排列时, 光子晶体光纤模场分布随温度变化显著, 其有效折射率和限制损耗的大小与温度成反比。保持孔间距不变, 占空比越大, 输入波长越长, 灵敏度越高。在此基础上, 提出了一种正九边形熔接点为锥形的单模光纤-光子晶体光纤-单模光纤马赫曾德干涉仪温度传感器,当波长为1 550 nm, 占空比为0.6, 温度范围为-20～80 ℃时, 该传感结构的温度灵敏度为0.112 2 nm/℃。

The temperature sensing characteristics of the Total Internal Reflection Photonic Crystal Fiber (TIR-PCF) with the air hole as the positive nine side shaped periodic array is investigated by using the full vector finite element method. The effects of different air hole arrangement, duty cycle and wavelength on the temperature characteristics are analyzed and compared with the photonic crystal fiber with hexagonal structure. The result shows that the PCF mode field distribution changes significantly with the change of temperature. The effective refractive index and the limitation of the size of the air hole is inversely proportional to the temperature of the air hole in the positive nine shape periodic arrangement. Keeping the distance between the holes constant, the results show that the larger the duty cycle or the longer the input wavelength, the higher the sensitivity will be. Then, we propose a kind of the positive nine side shaped periodic array and fusion point for cone SMF-PCF-SMF (Single-Mode Fiber, SMF) Mach-Zehnder Interferometer (MZI) temperature sensor. The result shows that when the wavelength is 1 550 nm and the duty cycle is 0.6, the temperature range from -20 to 80 ℃, and the temperature sensitivity of the sensing structure is 0.112 2 nm/℃.