High-Sensitivity and Anti-Interference Curvature Sensor Based on Optical Intensity Differential in Tapered Seven-Core Fiber

This paper presents a high-sensitivity and anti-interference optical intensity differential curvature sensor based on seven-core fiber (SCF), and its performance is verified through simulation. The sensor adopts a “single-mode fiber–tapered SCF” structure, using the light intensity ratio between the peripheral core and the central core for curvature demodulation. It enhances the sensitivity while effectively suppressing common-mode interference. The simulation results show that when the cone zone diameter of the tapered SCF is optimized to 30 µm, the mode coupling between the cores is significant, forming a strongly coupled super-mode transmission system. Based on the intensity differential principle, this sensor achieves excellent linear response within the curvature range of 0–10 m−1, with a sensitivity of −0.145/m−1. The sensor has a compact structure and simple fabrication process, providing new ideas and solutions to break through the technical bottlenecks of existing fiber curvature sensors, and has broad application prospects in engineering monitoring fields.