Enhancing refractive index sensing through a cascaded Mach–Zehnder interferometer with double-tapered segment in bent fiber

A novel refractive index sensor has been developed based on the Mach–Zehnder interferometer principle. This sensor was fabricated using a cascaded structure with double-tapered segments in one single mode fiber. Simulations and experimental results proved its effectiveness for measuring refractive indices in the approximate range of 1.341–1.356. It was found that the light intensity sensitivity of this sensor to sucrose solution is 460.79 dBm/RIU and the peak wavelength sensitivity is 116.97 nm/RIU, making it more suitable as a light intensity-based refractive index sensing structure. The demonstrated sensor, with excellent reusability and long-term stability, promotes practical applications in continuous monitoring of sugar content in agricultural products.