Magneto-optical isolators with flat-top responses based on one-dimensional magneto-photonic crystals

We propose two composite structures based on a one-dimensional magneto-photonic crystal basic structure and employ the 4 × 4 transfer matrix to investigate their transmission properties. One composite structure with total thickness of 15.09 μm achieves flat-top width of 3.5 nm and possesses Faraday rotation angle and transmittance waving at 45–53.50̊ and 98.75–99.73%, respectively. The other composite structure with the total thickness of 22.71 μm makes the flat-top width to 2.5 nm, and in the area of this bandwidth, Faraday rotation angle and transmittance fluctuate from 45̊ to 48.55̊ and 99.61% to 99.87%, respectively. Moreover, both of them are thin enough and show acceptable transmission bandwidths. These two structures can efficiently reduce the size of optical isolators and thus applying to the achievement of the integrated devices.