High-resolution asymmetric optical fiber sensor for simultaneous measurement of micro-displacement and temperature

Abstract A high-resolution asymmetric sensor is designed for simultaneously measuring temperature and micro-displacement. The sensor is based on a bent single-mode-multimode-single-mode (SMS) fiber structure, forming a balloon-like shape that incorporates two tapers of distinct diameters. This novel structure not only facilitates Mach–Zehnder interference but also strengthens the evanescent field exposure, resulting in two distinct dips that exhibit unique responses to micro-displacement and temperature. Therefore, the interferometer can measure both micro-displacement and temperature simultaneously. Experimental results demonstrate that the sensitivities of the micro-displacement and temperature for the two spectral dips are 807.7 pm μm −1 , 35.9 pm °C −1 and 341.0 pm μm −1 , 52.4 pm °C −1 , respectively. Meanwhile, the resolutions for micro-displacement and temperature are 0.011 μm and 0.310 °C, respectively. It is demonstrated that the micro-displacement sensitivity and resolution of the sensor in this work are significantly higher than those of previously reported designs. The sensor is a relatively simple structure to fabricate, is cost-effective and has both high sensitivity and resolution. It is, therefore, a promising candidate for various industrial applications, including aerospace, marine engineering and precision spatial positioning.