Curvature sensor based on Mach-Zehnder interferometer with vase-shaped tapers

A novel Mach-Zehnder Interferometer (MZI) formed by cascading two vase-shaped tapers in a single mode fiber (SMF) is proposed in this work. The vase-shaped taper is fabricated by fusion splicing a fiber sphere with a fiber tip by applying strong arc discharge. The curvature sensing characteristic of the proposed vase-shaped taper-based MZI is experimentally investigated, displaying that the interference spectrum has a blue shift with the increase of applied curvature. The sensor realizes a large range measurement of curvature from 0.9284 m−1 to 4.0470 m−1 with sensitivities of −8.41 nm/m−1 and −16.72 nm/ m−1 in the curvature range of 0.9284 m−1 to 2.4564 m−1 and 2.6025 m−1 to 4.0470 m−1, respectively. Its temperature-curvature cross-sensitivities are −0.0021 m−1/ °C and −0.0011 m−1/ °C in the two measurement ranges, which are lower than the corresponding curvature resolutions which are 0.0024 m−1 and 0.0012 m−1. The proposed sensor exhibits the advantages of low cost, negligible temperature cross-sensitivity, fine curvature sensitivity and large measurement scale.