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 0.9284m(-1) to 4.0470m(-1) with sensitivities of -8.41 nmim(-1) and-16.72 nm/m(-1) in the curvature range of 0.9284m(-1) to 2.4564m(-1) and 2.6025 m-1 to 4.0470m(-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 0.0024m(-1) and 0.0012m(-1). The proposed sensor exhibits the advantages of low cost, negligible temperature cross-sensitivity, fine curvature sensitivity and large measurement scale. (C) 2017 Elsevier B.V. All rights reserved.