Highly sensitive curvature fiber sensor based on an enhanced core diameter mismatch

In this study, a curvature fiber sensor based on an enhanced core diameter mismatch is experimentally proposed and theoretically investigated. The structure is fabricated by splicing two types of step multimode and coreless fibers to excite the high-order cladding modes to improve the curvature sensitivity. Experimental results show that the highest curvature sensitivities of the structure reach -114.74 nm/m(-1) in the Dip 1272 nm, -91.08 nm/m(-1) in Dip 1408 nm, and -61.10 nm/m(-1) in Dip 1644 nm in the measuring range of 0-0.49778 m(-1). Meanwhile, the sensor's temperature and strain responses were also tested, which shows little influence on the curvature measurement. Additionally, the proposed fiber sensor exhibits features of easy fabrication, simple structure, and high mechanical strength. This study proposes a device for curvature measurement with potential use in material mechanics and optical fiber sensor design. (c) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement