Refractive index and temperature-sensing characteristics of a cladding-etched thin core fiber interferometer

A high refractive index (RI) sensor based on an in-line Mach–Zehnder mode interferometer (MZI) is proposed. The sensor was realized by splicing a 2-cm length of cladding-etched thin core fiber (TCF) between two single mode fibers (SMFs). The TCF-structured MZI exhibited good fringe visibility as high as 15 dB in air and the high RI sensitivity attained a value of 1143.89 nm/RIU at a RI of 1.447. The experimental data revealed that the MZI has high RI sensitivity after HF etching realizing 2599.66 nm/RIU. Studies were performed on the temperature characteristics of the device. It is anticipated that this high RI sensor will be deployed in new and diverse applications in the chemical and biological fields.