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根据耦合模理论,对光纤布拉格光栅(FBG)的横向应变特性进行了深入研究,并采用数值分析方法对光纤布拉格光栅在平面应变和应力情况下进行了模拟分析:对于平面应变情况,一个谐振峰向波长增大的方向移动,而另一个谐振峰向波长减小的方向轻微移动;对于平面应力情况,两个谐振峰都向波长增大的方向移动。设计了相应的实验进行验证,实验结果与理论分析相符;该实验结果表明光纤布拉格光栅的横向应变情况介于平面应力和平面应变之间,而且更接近平面应力情况。根据理论分析,横向应变与纵向应变对波长漂移的贡献不一样,从而使三维应变测量成为可能。
According to the coupled mode theory, the transverse strain characteristics of fiber Bragg grating (FBG) are deeply studied. The numerical analysis is used to simulate the fiber Bragg grating in the plane strain and stress conditions. For the plane strain, a resonant peak Move toward the direction of increasing wavelength, while the other resonance peak moves slightly toward the direction of decreasing wavelength. For the case of plane stress, both resonance peaks move toward the direction of increasing wavelength. Corresponding experiments are designed to verify the experimental results consistent with theoretical analysis. The experimental results show that the transverse strain of fiber Bragg grating is between the plane stress and the plane strain, and closer to the plane stress. According to theoretical analysis, the contribution of lateral strain and longitudinal strain to wavelength shift is different, so that the three-dimensional strain measurement is possible.