(a) Normalized power of 1.55 μm versus the propagation distance, the coupling length of X-polarization, Y-polarization light is 7935.94 μm and 15242.63 μm, and (b) the extinction ratio versus the operable wavelength λ with different fiber length under the optimal structural parameters, the bandwidth in which the extinction ratio is lower than −20 dB is 226 nm as the fiber length is 14300 μm.