A high-sensitivity optical fiber temperature sensor based on the Vernier effect of cascaded fiber Sagnac interferometer (FSI) and Mach-Zehnder interferometer (MZI) is proposed and experimentally demonstrated. The FSI is composed of a 3 dB four-port coupler and a section of polarization maintaining fiber, which has high sensitivity and good stability as the sensing part. As the filtering part, MZI is made up of two three-port couplers by controlling the length of the two arms. The free spectral range (FSR) of these two interferometers is similar but not equal, so the cascade system can effectively amplify the temperature sensing sensitivity based on the vernier effect. The experimental results show that the temperature sensitivity of a single FSI is only −1.68 nm/°C, and the cascade system can amplify it to 14.30 nm/°C with a gain coefficient of 8.51, which is consistent with the theoretical results.

提出并实验证明了一种基于级联光纤萨格纳克干涉仪（FSI）和马赫-曾德干涉仪（MZI）的游标效应的高灵敏度光纤温度传感器。FSI由一个3dB的四端口耦合器和一段保偏光纤组成，作为传感部分灵敏度高，稳定性好。作为滤波部分，MZI由两个三端口耦合器通过控制两个臂的长度组成。这两种干涉仪的自由光谱范围（FSR）相似但不相等，因此级联系统可以有效地放大基于游标效应的温度传感灵敏度。实验结果表明，单个FSI的温度灵敏度仅为-1.68 nm/°C，级联系统可将其放大至14.30 nm/°C，增益系数为8。