Weak mode coupling measurement with EMD-based method in polarization-maintaining fibers

The intensity and position of coupling points in polarization-maintaining fibers (PMFs) caused by force and twist can be effectively detected by Polarization Coupling Measurement (PCM). The sensitivity of detection will decrease due to the movement of scanning Michelson interferometer. To detect the weak coupling point, an EMD-based method is proposed in this paper. The experimental results illustrate that the EMD-based method can suppress the noise and improve the SNR effectively. The DWT method is also performed for a comparative study. The results show that the EMD-based method is effective and applicable for PCM and the coupling point can still be detected when the intensity is as weak as − 70 dB.