Refractive index sensor based on tapered multicore fiber

•A novel refractive index sensor based on multicore fiber is proposed and demonstrated.•We simulated that how the RI change affect the cladding modes using finite element method.•We compared and analyzed sensing performance with different lengths of sensor structure.•The potential of suitable for realizing simultaneous multi-parameter measurement.

A novel refractive index (RI) sensor based on middle-tapered multicore fiber (TMCF) is proposed and experimentally demonstrated. The sensing structure consists of two singlemode fibers (SMF) and simply spliced a section tapered four-core fiber between them. The light injected from the SMF into the multicore fiber (MCF) will excite multiple cladding mode, and interference between these modes can be affected by the surrounding refractive index (SRI), which also dictates the wavelength shift of the transmission spectrum. Our experimental investigations achieved a sensitivity around 171.2 nm/RIU for a refractive index range from 1.3448 to 1.3774. All sensors fabricated in this paper show good linearity in terms of the spectral wavelength shift versus changes in RI.