Curvature sensor enabled by fiber ring microwave photonic filter

We propose a high-resolution curvature sensor utilizing seven-core fiber Bragg gratings (7-Core FBGs) interrogated by a fiber ring microwave photonic filter (FR-MPF). By mapping optical wavelength shifts to significant microwave frequency shifts, the system breaks the resolution limit of traditional spectral analysis, achieving a theoretical resolution of 0.26 × 10-2 m-1. Crucially, we optimized the system for high-speed interrogation, demonstrating a resolution of 0.65 × 10-2 m-1 even at measurement speeds exceeding 100 Hz. The system's multi-directional sensing capability and environmental stability were also experimentally validated, with average relative errors for curvature and direction of 1.09% and 1.91%, respectively. This work integrates high precision and dynamic capability into a compact sensing system, offering significant potential for real-time medical navigation and large-scale structural monitoring.