Highly stable and sensitive optical fiber temperature sensor based on vernier structure in a common-path interferometer using polarization-maintaining fiber

Achieving high sensitivity and robust environmental stability simultaneously remains a significant challenge in sensor research. Optical Vernier structure, serving as an excellent tool for substantially boosting sensing sensitivity, has become a current research hotspot. However, while it greatly improves sensitivity, the deterioration of environmental stability is inevitable. In this article, we propose and experimentally validate a temperature sensor based on the common-path interferometer Vernier structure (CPI-VS) using polarization-maintaining fiber (PMF). This sensor not only demonstrates high sensitivity (45.18 nm/℃) and robust environmental stability (with a 90.8 % improvement), but also achieves a detection limit of 0.011 ℃, surpassing both the single MZI (0.022 ℃) and the conventional DPI-VS (0.030 ℃). This sensing structure utilizes a single PMF based Mach-Zehnder interferometer (MZI) and integrates a Faraday rotation mirror (FRM) to enable two orthogonal polarized light components to propagate sequentially. Due to the Vernier effect, the sensor’s sensitivity is enhanced about 3660 times compared to a single MZI by adjusting the ratio of the arm length to the arm length difference. Experimental results are consistent with theoretical simulations. Furthermore, the sensor design improves environmental stability by 90.8 %, addressing the traditional trade-off between sensitivity and stability in fiber-optic interferometers. This work offers a novel approach to the design and application of high-sensitivity, environmentally stable fiber-optic sensors.