介绍了采用匹配光纤布拉格光栅解调法(detector FBG)进行强度解调的基本原理,选择反射谱与传感光纤布拉格光栅(sensor FBG)反射谱部分重叠的解调光栅,通过探测解调光栅反射光强的变化进行解调。对这种光栅匹配解调法引起的反射光功率与应力为高斯函数而不是线性对应的问题――双值问题进行了研究,提出了一种新颖的多档光栅并联解调的解决方案,选择并联解调光栅的中心波长和带宽,从而实现所传感的应力与探测到的光功率之间的线性对应,并建立理论模型进行了模拟,从理论上进行了公式推导。最后以两档光栅并联解调为例,用实验证明了该方案切实可行,同时达到的传感范围为522 με,测量精度为2.6 με。

The method of intensity demodulation with matched fiber Bragg gratings (FBG) is introduced. The FBG whose reflection spectrum overlaps with that of sensor FBG is selected to demodulate signals by detecting the changes of the intensity of reflected laser of demodulation FBG. The question that the intensity of reflected laser is a Gauss function of strain, i.e., two-values question caused by this method in strain sensors is studied. And a novel method that demodulation FBGs with well selected Bragg wavelength and bandwidth are in parallel connection is deduced so that the intensity of reflected laser is linear with strain. A theoretical model is set up and formulas are deduced. Finally this method is proved by experiment with two demodulation FBGs to be practicable and the sensor range is 522 με and the sensitivity is 2.6 με.