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两光纤布拉格光栅(FBG)的光谱失配会使其构成的光纤法布里-珀罗(FFP)传感系统的干涉条纹可见度降低,从而影响探测性能。基于弱反射率FBG反射谱的高斯波形近似,推导了光谱失配引起的可见度变化表示式。实验测量了干涉型FFP传感系统的可见度曲线,对理论分析进行了验证。研究表明,反射谱旁瓣对光谱失配引起的可见度变化有重要影响。从光谱匹配的角度,采用高斯切趾光栅的FFP传感系统优于普通均匀光栅的系统。
Spectral mismatch between two fiber Bragg gratings (FBGs) can reduce the visibility of interference fringes in the fiber Fabry-Perot (FFP) sensing system, which affects the detection performance. Based on the Gaussian waveform approximation of FBG reflectance spectrum with weak reflectivity, the expression of visibility change caused by spectral mismatch is deduced. The experiment measured the visibility curve of interference type FFP sensor system, and verified the theoretical analysis. Studies have shown that the sidelobes of the reflections have a significant impact on the change in visibility due to spectral mismatch. From a spectral matching point of view, the FFP sensing system with Gaussian apodized gratings is superior to a conventional uniform grating system.