Circular polarization bandpass filters based on one-dimensional magnetophotonic crystals

The realization of circular polarization band pass filters based on defect mode splitting in one-dimensional magnetophotonic crystals (1D-MPCs) was investigated theoretically using the 4 x 4 transfer matrix method. The analytical formulas of the resonance conditions are derived. The results reveal that for a specific repetition number of the microcavity type 1D-MPC structure, the defect mode splits into two completely separated modes, corresponding to right- and left-circular polarization resonances. It is shown that these modes have purely circular polarization states, which enables us to propose the structure as a single and dual channel circular polarization filter. Furthermore, the tuning properties of the considered structure under the variation of exterior magnetic field are studied.