Distributed Bending Sensing of Few-mode Fiber Based on Optical Frequency Domain Reflectometry

A novel scheme to realize distributed bending sensing along the few mode fiber based on optical frequency domain reflectometry is proposed. The feasibility of the proposed method has been demonstrated both theoretically and experimentally on a two-mode fiber. The bending information is obtained by demodulating the changes of the effective refractive index and differential mode delay between LP 01 and LP 11 modes. The experimental results are in good agreement with those obtained by simulation when the bending diameter changes from 4 cm to 8 cm. We believe that this characterization method paves the way for developing high spatial resolution distributed bending sensor and can also be generalized to more modes case.