Bandwidth Enhancement of Epsilon-Near-Zero Supercoupling with Inverse-Designed Metamaterials

Epsilon-near-zero (ENZ) materials exhibit unique electromagnetic properties that enable efficient wave transmission through channels of arbitrary geometry, which is known as ENZ supercoupling or tunneling. However, the supercoupling effect is typically confined to an inherent narrow bandwidth, which significantly restrict its practical applications. In this paper, a feasible method is proposed that enhanced the bandwidth of ENZ supercoupling. By optimizing the structure of an inverse-designed pixel metamaterial inserted into the ENZ channel, multiple Fabry-Perot (FP) modes are properly regulated and coupled, facilitating multimode superposition to enhance the bandwidth for high-efficiency signal transmission in ENZ channels with arbitrary geometry. Furthermore, a prototype is constructed at microwave frequency to validate the performance of the proposed method, which opens new avenues for the development of broadband and geometry-independent electromagnetic devices with the benefit of ENZ materials.