A fiber temperature sensor consisting of two cascaded reflective film-fiber-reflective film Fabry-Pérot (FP) cavities is proposed. The lengths of the two FP cavities are similar, but with small differences in their free spectral ranges (FSR) to create Vernier effect. The sensor operates similar to a Vernier caliper, where one FP cavity serves as a reference and the other as a sensing element. Experimental results demonstrate that the extinction ratios of cascaded system exceed 15 dB. The temperature sensitivity of the sensor reaches 1.14 nm/°C, offering advantages such as a wide measurement range, high sensitivity, good linearity, simple structure and low cost. Additionally, the fiber FP cavities are uncomplicated and compact, and their use as sensing elements helps avoid temperature inhomogeneity. This makes the sensor reliable, practical, and suitable for a wide range of applications.

中文翻译：

---

基于法布里-珀罗腔产生光学游标效应的光纤温度传感器

提出了一种由两个级联反射膜-光纤-反射膜法布里-珀罗(FP)腔组成的光纤温度传感器。两个 FP 腔的长度相似，但其自由光谱范围 (FSR) 略有差异，以产生游标效应。该传感器的工作原理类似于游标卡尺，其中一个 FP 腔用作参考，另一个用作传感元件。实验结果表明级联系统的消光比超过15 dB。该传感器的温度灵敏度达到1.14 nm/℃，具有测量范围宽、灵敏度高、线性好、结构简单、成本低等优点。此外，光纤 FP 腔简单且紧凑，将其用作传感元件有助于避免温度不均匀性。这使得该传感器可靠、实用且适合广泛的应用。