We propose and demonstrate an optical fiber vector curvature sensor based on a long-period fiber grating (LPFG) inscribed in Panda type polarization-maintaining fiber (PMF) using CO2-laser heating and tapering system. The uniform heating approach removes the necessity of CO2-laser exposure alignment along the axis of PMFs during grating fabrication. A serial of PMF-LPFGs with grating period from 350 to 490 μm with a step of 20 μm have been fabricated experimentally. The curvature response of the fast and slow axis resonance dips for the LPFG with a period of 450 μm was investigated in the curvature range from 0 to 4.137 m-1 at four bending orientations. The maximum curvature sensitivities were measured to be 9.26 and -6.89 nm/m-1 for the fast and slow axis LP15 modes, respectively. The sensor can achieve 2-dimensional bending direction recognition. The proposed grating has potential application as a vector curvature sensor.

中文翻译：

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基于保偏光纤长周期光栅的矢量曲率传感器


我们提出并演示了一种基于长周期光纤光栅（LPFG）的光纤矢量曲率传感器，该传感器使用CO2激光加热和锥形系统刻在熊猫型保偏光纤（PMF）中。均匀加热方法消除了在光栅制造过程中沿 PMF 轴进行 CO2 激光曝光对准的必要性。实验制作了一系列光栅周期为350~490μm、步长为20μm的PMF-LPFG。研究了周期为 450 μm 的长周期光栅在 0 到 4.137 m-1 曲率范围内四个弯曲方向的快轴和慢轴共振谷的曲率响应。测得快轴 LP15 模式和慢轴 LP15 模式的最大曲率灵敏度分别为 9.26 和 -6.89 nm/m-1。该传感器可实现二维弯曲方向识别。所提出的光栅具有作为矢量曲率传感器的潜在应用。