One-dimensional magneto-photonic crystals with flat-top responses for Magneto-optical isolators

The 4 x 4 transfer matrix method is used to investigate the broadband optical isolation property of two different one-dimensional magneto-photonic crystal structures. The results show that the first structure makes broadband optical isolation come true. When the angle between the applied magnetic field and optical axis is set as 41.0 degrees, its bandwidth achieved 3 nm with a 22.90 mu m-thickness, the Faraday rotation angle fluctuated from 45 degrees to 48.89 degrees and transmittance achieved 99.86 similar to 99.95%. The other structure with total thickness of 18.61 mu m achieves a 1 nm-bandwidth optical isolation with the Faraday rotation angle fluctuated from 45.83 degrees to 45.89 degrees and transmittance fluctuated from 98.53% to 98.78%, when the applied magnetic field is nearly parallel to the optical axis. This structure ensures the achievement of optical isolation without adjusting the applied magnetic field.