Optimization of Epsilon-and-mu-near-zero Refractive Index Photonic Structure to Design Unidirectional Transmission Device

In this study, we introduce a novel approach for designing an unidirectional transmission device by using a photonic crystal (PC) structure that exhibits the properties of epsilon-mu-near-zero media. The selected PC structure consists of dielectric rods and positions of certain preselected rods in y-direction are optimized via an evolutionary algorithm to obtain the unidirectional transmission of light. Finite-difference time-domain (FDTD) method is used to perform numerical analyses for the proposed device. In addition, experiments are carried out at microwave frequencies to demonstrate the unidirectional light transmission. It is shown that a good agreement between numerical calculations and experimental measurements is achieved.