基于游标效应的萨格纳克干涉仪温度传感器

Temperature Sensor of Cascaded Sagnac Interferometer Based on Vernier Effect

摘要:

提出了一种基于光学游标效应的级联光纤萨格纳克干涉仪和光纤模态干涉仪高灵敏度温度传感器,并对其传感特性进行了实验研究。光纤萨格纳克干涉仪由一段保偏光纤和3dB四端口耦合器组成,光纤模态干涉仪由一段少模光纤与两段单模光纤熔接形成。选取光纤萨格纳克干涉仪作为温度传感器,光纤模态干涉仪充当滤波器。通过控制保偏光纤和少模光纤的长度,使光纤萨格纳克干涉仪的自由光谱范围为2.63nm,光纤模态干涉仪的自由光谱范围为2.82nm,两者的自由光谱范围相近又不相等,从而形成光学游标效应。实验结果显示,单个光纤萨格纳克干涉仪的温度灵敏度为-1.30nm/℃,级联光纤模态干涉仪后,其温度灵敏度提高到-18.19nm/℃,放大倍数为13.99。该传感器制造工艺简单,稳定性好,不需要特殊的增敏材料来提高灵敏度。

Abstract:

In this paper, a cascaded fiber optic Sagnac interferometer and a fiber optic modal interferometer high sensitivity temperature sensor based on vernier effect were presented. The sensing properties was researched experimentally. The fiber optic Sagnac interferometer consisted of a section of polarization maintaining fiber and 3dB four-port coupler, and the fiber optic modal interferometer was formed by a fusion of few-mode fiber and two segments of single-mode fiber. The fiber optic Sagnak interferometer was selected as temperature sensor and the fiber optic modal interferometer as filter. By controlling the length of polarization maintaining fiber and few-mode fiber, the free spectral range of the fiber optic Sagnac interferometer was 2.63nm, and the free spectral range of the fiber optic modal interferometer was 2.82nm. The free spectral ranges were similar and unequal, thus the optical vernier effect was formed. The experimental results show that the temperature sensitivity of a single fiber Sagnak interferometer is -1.30nm/℃. After cascading the fiber mode interferometer, the temperature sensitivity increases to -18.19nm/℃ with a magnification of 13.99. The sensor has a simple manufacturing process, good stability, and does not require special sensitization materials to improve sensitivity.