Zhu Chen, Roman Muhammad, Zhuang Yiyang, Huang Jie
Opt Lett. 2022 Jun 1;47(11):2810-2813. doi: 10.1364/OL.461307.
The Vernier effect has been widely used in the field of measurement and instrumentation for sensitivity enhancement. Single-point optical fiber sensors based on the Vernier effect have been extensively reported in recent years. In this Letter, for the first time, a distributed optical fiber sensor based on microwave photonics with improved sensitivity enabled by the Vernier effect is demonstrated. Distributed sensing is realized by interrogating a Fabry-Perot interferometer (FPI) array formed by cascaded reflectors along an optical fiber using an optical carrier-based microwave interferometry (OCMI) system. A reference FPI is also included in the system. The interferogram of each of the sensing FPIs can be unambiguously reconstructed and superimposed with the reconstructed interferogram of the reference FPI to generate the Vernier effect. By tracking the spectral shift of the envelope signals in the superimposed spectra, the measurement sensitivities of the sensing FPIs can be significantly improved. A simple direct modulation-based OCMI system is used in the proof-of-concept demonstration, showing sensitivity-enhanced distributed sensing capability. Moreover, the sensitivity amplification factor can be adjusted by varying the optical length difference of the sensing and reference FPIs, similar to that of Vernier effect-based single-point optical fiber sensors.
游标效应已在测量和仪器仪表领域中广泛用于提高灵敏度。近年来，基于游标效应的单点光纤传感器已有大量报道。在本信函中，首次展示了一种基于微波光子学的分布式光纤传感器，其通过游标效应实现了灵敏度的提高。通过使用基于光载波的微波干涉测量（OCMI）系统，对沿光纤由级联反射器形成的法布里-珀罗干涉仪（FPI）阵列进行询问，实现了分布式传感。该系统中还包含一个参考FPI。每个传感FPI的干涉图能够被明确重建，并与参考FPI的重建干涉图叠加以产生游标效应。通过跟踪叠加光谱中包络信号的光谱偏移，传感FPI的测量灵敏度可得到显著提高。在概念验证演示中使用了一个基于简单直接调制的OCMI系统，展示了灵敏度增强的分布式传感能力。此外，类似于基于游标效应的单点光纤传感器，灵敏度放大因子可通过改变传感和参考FPI的光学长度差来调整。
