Resonant Fiber Optic Current Sensor Based on Broadband Light Source

The monitoring of current in real time is crucial for the maintenance of the power grid system. In this paper, we propose and experimentally demonstrate a novel fiber optic current sensor based on resonance frequency difference detection using a single-mode fiber ring resonator (FRR). The sensing system utilizes the Faraday effect, which behaves as the resonance frequency difference between the two circularly polarized lightwaves in the FRR. By measuring this resonance frequency difference, the current can be accurately determined. The current sensor exhibits a sensitivity of 41.53 Hz/A within a measurement range of 0–400 A, with a relative error of less than 0.2%, and an optimized current accuracy of 0.5 A. The main limiting factor affecting the noise performance of the system is analyzed. This research provides new insights into research and low-cost applications in the field of current sensing.