Multipoint Two-Dimensional Curvature Optical Fiber Sensor Based on a Nontwisted Homogeneous Four-Core Fiber

We have implemented a multipoint two-dimensional curvature optical fiber sensor based on a nontwisted homogeneous four-core fiber. A theoretical approach to model the mechanical behavior of these fibers under curvature conditions has been developed. Two shape sensors composed of an array of FBGs inscribed in the four-core fiber have been implemented to corroborate the theoretical analysis with the experimental results. The characterization of the proposed shape sensors showed their ability to measure the curvature radius, the curvature direction, and any external applied force related to both uniform and nonuniform curvatures with high accuracy.