A Curvature Mach-Zehnder Interferometer Fiber Sensor Based on Triple Cladding and Coreless Fiber

We propose a Mach-Zehnder Interferometer (MZI) sensor fabricated by a triple-cladding fiber (Tr-CF) and a coreless fiber (CLF). The sensor comprises a segment of Tr-CF sandwiched between two segments of CLF, with single-mode fibers (SMFs) connected at both ends, forming a SMF-CLF-Tr-CF-CLF-SMF structure. The mode mismatch between SMF and CLF efficiently excites higher-order modes, leading to increased cladding modes in Tr-CF. Enhanced sensitivity is achieved as light interacts with the external environment through the cladding layer of Tr-CF. Experimental results demonstrate a maximum curvature sensitivity of 122.83098 dB/m-1 as the curvature varies from 0 m-1 to 0.09142 m-1. These findings highlight the sensor's exceptional curvature sensitivity and its potential applications in engineering measurement, health detection, and other fields.