结合均匀光栅在受到非均匀应变时会产生啁啾效应的原理, 提出了一种利用正弦结构将均匀光栅调制成啁啾光栅的方法。 设计了正弦结构的基底材料, 将光纤光栅粘贴在基底材料的应变非均匀区, 通过施加拉伸载荷将其产生的应变引入FBG栅区, 使得FBG产生了啁啾效应, FBG被调制成具有多个反射峰和宽带宽的啁啾光栅; 使用有限元软件对正弦结构拉伸载荷下的应变进行了仿真, 得到了正弦结构不同位置的应变云图; 实验结果在位移载荷最大为8 mm时, 得到了带宽增加5倍, 反射谱具有多个反射峰的啁啾光栅; 结合传输矩阵法对啁啾光栅的反射谱进行光谱仿真重构, 仿真光谱与实验光谱趋势基本吻合。

The reflective spectrum power and the bandwidth of the fiber Bragg grating (FBG) under gradient strain are researched and experimentally demonstrated. The gradient strain is applied on the FBG, which can induce FBG bandwidth broadening, resulting in the variation of reflective power. Based on the coupled-mode theory and transfer matrix method, the segmental linear relationship between the gradient strain, the reflective power, and the bandwidth is simulated and analyzed, and the influence of the FBG length on the reflective spectrum is analyzed. In the experiment, the strict gradient stain device is designed; the experimental results indicate that the reflective optic power and the bandwidth of the FBG under gradient stain are concerned with the length of the FBG. Experimental results are well consistent with the theoretical analysis, which have important guiding significance in the FBG dynamic sensing.