利用高频CO2激光单侧曝光技术及双芯光纤的非对称性, 设计并制作了一种长周期光纤光栅弯曲矢量传感器.成栅机理分析表明, 光纤边缘处嵌入的纤芯极大地增强了包层中的残余应力, 在CO2激光脉冲曝光时, 残余应力释放作用增强, 光栅质量更高; 同时, 双芯光纤的非对称结构以及CO2激光单侧曝光使得光纤器件对偏振非常敏感, 写制的光纤光栅在1 555.4 nm谐振波长处的偏振相关损耗高达20.8 dB.弯曲传感测试表明, 在0~1.235 m－1曲率范围内, 光纤光栅向+y方向弯曲时, 透射谱谐振峰波长向长波方向漂移, 灵敏度为2.37 nm/m－1; 光纤光栅向－y方向弯曲时, 谐振峰波长向短波方向漂移, 灵敏度为1.80 nm/m－1.该弯曲矢量传感器结构简单, 灵敏度高, 可广泛应用于道路、桥梁等建筑的安全检测.

A long period fiber grating bend sensor was fabricated in mismatched twin core fiber by CO2 laser irradiation. Theoretical analysis indicate that the fiber core located at the edge of the cladding greatly enhances the residual stress. Under CO2 laser exposure,the long period fiber grating experiences a high quality. Moreover, the fiber grating is sensitive to polorization property due to the asymmetrical structure, the polarization dependent loss value of the long period fiber grating is as high as 20.8dB at the resonant wavelength of 1 553.3 nm. Sensing experiment reveals that it can distinguish the orientation of the curvature by the resonant peak showing a red or blue shift. The fiber grating experiences significant sensitivities of 2.37 nm/m－1 and 1.80 nm/m－1 with the micro-bending range of 0~1.235m－1 for +y and －y axis directions. The proposed sensor has the advantages of simple structure and high sensitivity. It could be used in struction health monitoring applications including roads and bridges.