Multi-Parameter Interferometric Sensor Based on a Reduced Diameter Core Axial Offseted Fiber

We report an optical sensor based on the interference pattern created by an all-fiber Mach-Zehnder setup. This pattern is produced by the combination of the core and cladding modes that are excited on a fiber with reduced diameter fusion spliced to a single-mode fiber with a 4-μm core axial offset. Discrete measurements of refractive index and temperature are achieved with sensitivities of 8.8 nm/refractive index units and 39.2 pm/°C, respectively, and also distributed measurements of liquid level up to 120 mm are made with a sensitivity of 6 pm/mm.