Abstract In this study, a new type of structure of optical fiber pressure sensor (OFPS) based on polarization modulation is proposed, which selects a high-birefringence fiber (HBF) as the sensing unit to measure the pressure in the fluid medium. The PM-1550-01 fiber produced by NTK Photonics Inc. is evaluated as the sample in our subject. Firstly, the regularities of birefringence variation on the PM-1550-01 followed by the external pressure load and the ambient temperature are analyzed by the finite element method (FEM). The results show that the pressure sensitivity is 2.05 × 10−6 RIU/MPa in the pressure range of 0–100 MPa, and the temperature sensitivity is 7.27 × 10−10 RIU/°C in the temperature range of 0–100 °C. Thus, the pressure-temperature cross-sensitivity is only 0.355 kPa/°C in theory. Secondly, the expression of the output light intensity of the introduced OFPS is deduced based on the principles of polarization interference and phase modulation. Combined with simulation results, the measurement ranges of the sensor can be set and adjusted by the length of the sensing unit. Finally, the proposed OFPS is fabricated and external pressure tests within the range of 0–50 MPa are completed. The results show that the pressure sensitivity is approximately 0.145 dB/MPa in the pressure range of 0–44 MPa. There is a fine consistency between the experimental data and simulation results. In addition, the proposed OFPS has many other advantages, such as small size, simple fabrication process and large measurement range, which make it appropriate to be applied in high-pressure measurement in hostile conditions, e.g., downhole and ocean-bottom.

中文翻译：

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一种新型结构的基于偏振调制的光纤压力传感器

摘要 本研究提出了一种新型结构的基于偏振调制的光纤压力传感器（OFPS），它选择高双折射光纤（HBF）作为传感单元来测量流体介质中的压力。NTK Photonics Inc. 生产的 PM-1550-01 光纤在我们的课题中被评估为样品。首先，通过有限元方法（FEM）分析了 PM-1550-01 随外部压力负载和环境温度的双折射变化规律。结果表明，0-100 MPa压力范围内压力灵敏度为2.05×10-6 RIU/MPa，0-100°C温度范围内温度灵敏度为7.27×10-10 RIU/°C . 因此，理论上压力-温度交叉敏感性仅为0.355 kPa/°C。第二，根据偏振干涉和相位调制原理，推导出引入的OFPS输出光强的表达式。结合仿真结果，可以通过传感单元的长度来设置和调整传感器的测量范围。最后，所提出的 OFPS 被制造出来，并完成了 0-50 MPa 范围内的外部压力测试。结果表明，在 0-44 MPa 的压力范围内，压力灵敏度约为 0.145 dB/MPa。实验数据与仿真结果具有良好的一致性。此外，所提出的OFPS具有体积小、制作工艺简单、测量范围大等优点，适用于井下、海底等恶劣条件下的高压测量。