Simulation Refractive Index Dual Core Fiber Optic Sensor Based on Mach-Zehnder Interferometer

In this article a dual-core fiber optic sensor based on mach-zehnder interferometer for measurement refractive index changing is simulated. In this structure one of the cores is doped with germanium and the other with phosphorus. They operate as interferometer arms. Since the length of both arms are equal, interference pattern is formed by the refractive index difference of cores. One of the cores is considered as reference arm and the evanescent field of the other core interacts with surrounding environment. The interference pattern shifts with changing the refractive index of the surrounding environment. The sensor sensitivity is greatly dependent on evanescent field penetration into the external medium which can be increased by chemical etching or side polishing of fiber cladding. Simulation results show that the maximum achieved sensitivity is 643.85 nm/RIU which could be used for fiber optic biosensors.