Refractive index and temperature sensor based on optical fiber Mach–Zehnder interferometer with trapezoid cone

Abstract

An optical fiber sensor for simultaneous measurement of refractive index (RI) and temperature is achieved by using an optical fiber Mach–Zehnder interferometer (MZI) with two core-offset trapezoid cone structures, in which part of the core mode light will be coupled into cladding modes when passing through the first trapezoid cone and the two parts of light will combine in the second one and interfere with each other over there. The transmission spectrum would vary with the RI and the temperature. The experimental data show that the RI sensitivities of the two interference valleys are −35.93 and −51.14 nm / RIU, respectively. The temperature sensitivities of them are 0.05 and 0.04 nm / ° C, respectively. Therefore, it can be realized to gauge the RI and the temperature simultaneously. The proposed sensor can also be applied to chemistry and biology which has broad application prospects.