为了提高光纤横向压强传感器传感系数,降低温度对压强传感的影响,提出一种具有“三明治”结构的光子晶体光纤,并利用有限元法对其布里渊动态光栅传感特性进行数值模拟。研究了不同压强和温度条件下光子晶体光纤双折射频移的变化,分析了光子晶体光纤结构对其传感特性的影响,结果表明:设计的光子晶体光纤具有高传感精度,0~40 ℃下光子晶体光纤慢轴方向上双折射频移的压强传感系数约为692 MHz/MPa,光纤快轴方向上压强传感系数约为-404 MHz/MPa,0~40 MPa下温度系数仅为0.18 MHz/℃;与利用普通保偏光子晶体光纤设计的传感系数为199 MHz/MPa的压强传感系统相比,灵敏度提高了493 MHz/MPa。设计的光子晶体光纤提高了横向压强传感器传感系数且不易受温度的影响,适用于高精度静水压强传感领域。

In this paper, we proposed a photonic crystal fiber (PCF) with a sandwiched structure to improve the sensitivity of the transverse pressure sensors and decrease the interference caused by temperature. In addition, we used a finite element method (FEM) to simulate the sensing characteristics of its Brillouin dynamic grating. Furthermore, we investigated the birefringence-induced frequency shift of the proposed PCF at different pressures and temperatures and analyzed the influence of the PCF structure on its sensing characteristics. The results show that the designed PCF has high sensing precision. At 0--40 ℃, the pressure sensitivity on the slow and fast axes was about 692 MHz/MPa and -404 MHz/MPa, respectively; the temperature sensitivity was only 0.18 MHz/℃ at 0--40 MPa. In comparison with the pressure sensing system designed with a conventional polarization-maintaining PCF, with a sensitivity of 199 MHz/MPa, the sensitivity of our PCF was increased by 493 MHz/MPa. In conclusion, the PCF proposed in this work improves the sensitivity of the transverse pressure sensors and eliminates the interference of temperature, having potential applications in high-precision transverse pressure sensing.