Unidirectional transmission in two-dimensional photonic crystal composed of parity-time symmetric and magneto-optical materials

In this study, a one-way electromagnetic waveguide consisting of magneto-optical (MO) and parity-time (PT)-symmetric materials was constructed. Due to the composite boundary conditions, this waveguide simultaneously has two unidirectional dispersive curves and two different unidirectional mechanisms. One unidirectional mechanism is breaking the time-reversal symmetry of MO materials, and the other unidirectional mechanism is asymmetric complex eigenvalues in the local PT symmetrical configuration. The designed structure provides an effective approach to control the directions of electromagnetic waves.