Research on polarization characteristics of comb filter based on microfiber Sagnac ring

A comb filter based on microfiber Sagnac ring is proposed. The transmission spectrum of the proposed comb filter is theoretically analyzed. And the polarization characteristics of the comb filter are experimentally demonstrated. The experimental results show that the variation of polarization angle will cause the transmission spectrum drift and the filter depth variation. The variation of wave peak intensity is approximately sinusoidal waveforms through rotating the polarization controller. By studying the polarization characteristics of the comb filter, the comb filter can be better applied to dense wavelength division multiplexing system.