Wideband Epsilon‐Near‐Zero Supercoupling Control through Substrate‐Integrated Impedance Surface

Abstract

Abstract The supercoupling phenomenon of electromagnetic wave through arbitrary shaped epsilon‐near‐zero (ENZ) material channels has attracted considerable attention recently, leading to numerous intriguing applications. It has been demonstrated that around the cutoff frequency of fundamental TE 10 mode, waveguide behaves as the 2D homogenous ENZ material. However, for a given waveguide geometry, the ENZ operating bandwidth is inherently narrow and the center frequency is fixed. Here, a reconfigurable ENZ medium is proposed and experimentally demonstrated with a wideband‐tunable supercoupling effect by means of inserting a metasurface inside the waveguide, named as substrate‐integrated impedance surface (SIIS). With different insertion depth (which can be mechanically tuned) of SIIS, the ENZ supercoupling frequency can be precisely controlled. The proposed technique not only achieves wideband tuning of the ENZ supercoupling, especially to control the enhanced group delay of the electromagnetic waves, thereby offering a promising way toward for tunable slow‐light devices, such as light storage and processing components.