Non-reciprocal Transmission of Electromagnetic Waves in Asymmetric Photonic Crystals

The non-reciprocal transmission properties of transverse electric (TE) mode waves are investigated for two asymmetric, complex photonic crystals composed of magnetic gyrotropic and normal media. Three pairs of non-reciprocal transmission peaks in three different bandgaps for forward and backward waves occur because of optical Tamm states (OTSs) at the interface between the photonic crystals. Numerical results indicate that the non-reciprocal transmission properties are influenced by the incident angles, gyrotropic permeability, and number of layers of the photonic crystals. The asymmetric structure with multiple non-reciprocal transmission peaks at a certain incident angle can provide promising opportunities for the design of multichannel isolators.