Twofold unidirectional properties of parity-time symmetry structure under magneto-optical modulation.

In order to achieve tunable parity-time (PT) symmetry system, we design a PT-symmetry structure including magneto-optical material. We use the transfer matrix method to study the optical properties of the designed structure under the modulation of magnetic field. The structure system takes on twofold unidirectional properties, i.e., the reflectance and the transmittance are dependent on both the incidence direction and the incidence angle. The unique band-edge modes with the system have both enhanced reflectance and transmittance in one incidence direction or angle but lead to an absorption effect in the opposite incidence direction or angle. The reversal of magnetic field direction will all lead to the exchanging of the left band-edge modes and the right band-edge modes. [ABSTRACT FROM AUTHOR]