Fig. 1. Configuration of fiber current sensor based on fiber loop scheme

Fig. 2. Configuration of fiber current sensor based on single light path detection and fiber loop scheme

Fig. 3. Evolution process of light polarization between the SPSM couplers, which only allows light polarized along the slow axis to pass through

Fig. 4. Experiment setup

Fig. 5. Output results under different currents measured by digital oscilloscope

Fig. 6. Relationship between current intensity and normalized light intensity

Fig. 7. Relationship between round number K and current sensitivity k