Efficient optical fibre sensor for measuring Fe element in liquid

Abstract Photonic crystal fiber interferometers are widely used in sensing applications owing to their unique properties. In this research, a Photonic crystal fiber solid core Large Mode Area-10 mm based on Mach–Zehnder modal interferometer for sensing Fe element concentration in water is presented. The general structure of the sensor was realized by fusion splice Photonic crystal fiber with different lengths between two single mode fibers. The air holes at the fusion splice region are fully collapsed; thus, the core and cladding mode can be coupled and recombined. The sensor was immersed in solutions at different concentrations (2%, 5%, 10%, 15% and 20%) exhibited diverse refractive indices in the range of 1.3428–1.3439. The sensitivity was 42.446 nm/RIU when the Photonic crystal fiber Large Mode Area-10 mm was 1 cm, but the value changed to 44.244 and 31.654 nm/RIU with PCF lengths of 2 and 3 cm, respectively.