High-sensitivity strain sensor with air microbubble based on the Vernier effect

A highly sensitive optical fiber strain sensor with simple structure, easy preparation and temperature insensitivity is proposed. It consists of a parallel Fabry-Pérot Interferometer (FPI) based on the Vernier Effect (VE). The sensing cavity (FPI S ) is formed by two single-mode fibers (SMFs) by fusion splicer arc discharge, and the reference cavity (FPI R ) consists of two SMFs inserted into a hollow capillary tube（HCT）. The sensor has a high strain sensitivity of −42.04 pm/µε and an ultra-low temperature cross-sensitivity of 0.022 µε/°C, which reduces the measurement errors caused by temperature variations. At the same time, stable experimental measurements show that the interference fringes change by less than 20 pm. This sensor combines high strain sensitivity, ultra-low temperature cross-sensitivity, and stable performance for precise strain measurement applications.