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介绍了一种基于3×3和2×2光纤耦合器构成的非平衡马赫-曾德尔干涉仪的波长解调方案。理论分析和数据对比表明,相对于由两个2×2光纤耦合器构成的马赫-曾德尔干涉仪,本干涉仪具有宽谱的灵敏度、能跟踪波长的变化方向和相位展开的优点。实验方案用于测量固定在悬臂梁上的传感光纤布拉格光栅(FBG)的峰值波长变化,获得了±1 pm的静态波长解调精度,在10 Hz处的动态分辨率为27 n/εHz。相位展开算法使得应变测量范围达到了2014με,对应的相位变化为3.22π。
A wavelength demodulation scheme based on unbalanced Mach-Zehnder interferometer consisting of 3 × 3 and 2 × 2 fiber couplers is introduced. The theoretical analysis and data comparison show that this interferometer has the advantages of broad spectrum sensitivity and tracking the direction of wavelength variation and phase unwrapping relative to the Mach-Zehnder interferometer composed of two 2 × 2 fiber couplers. The experimental protocol was used to measure the peak wavelength variation of a FBG mounted on a cantilever and achieved ± 1 pm static wavelength demodulation accuracy with a dynamic resolution of 27 n / εHz at 10 Hz. Phase expansion algorithm makes the strain measurement range reached 2014με, the corresponding phase change is 3.22π.