Fig. 1. Spatial diagram of multi-core optical fiber

Fig. 2. Diagram of local curvature of optical fiber

Fig. 3. Schematic of OFDR system

Fig. 4. Diagram of Rayleigh scattering at scattering point i

Fig. 5. IQ modulation system

Fig. 6. Flow chart of OFDR signal demodulation^[23]

Fig. 7. Diagram of OFDR distributed fiber strain vector sensing system based on IQ modulation

Fig. 8. Time-frequency diagram of linear sweep signal

Fig. 9. Linear sweep spectrogram

Fig. 10. Relationship between line width of light source and sensing distance

Fig. 11. Angular resolution as a function of sweep range and curvature

Fig. 12. Relationship between angular resolution and sweep range when curvature is 1.78 m^-1

Fig. 13. Rayleigh scattering signal in middle core of seven-core fiber

Fig. 14. Results of seven core correlation peak migration and demodulation

Fig. 15. Diagram of bending direction angle of multi-core fiber

Fig. 16. Comparison of theoretical and measured curvatures