Fig. 1. Optical path diagram measuring the polarization-coupling distribution of fiber coil and beat length of used fiber

Fig. 2. Interference characteristic for polarization-coupling tests of PM fiber

Fig. 3. Relationship of PM fibers in WLI

Fig. 4. Polarization coupling distribution of fiber coil 1

Fig. 5. Polarization-coupling distribution of fiber coil 2

Fig. 6. Testing result of polarization-coupling distribution near the exit fusion splice of fiber coil 2