Realization of Planar Focusing Configuration Based on Hyperbolic Metasurface

Hyperbolic metasurface is a periodic arrangement of unit cells, composed of metals and dielectrics, that exhibit hyperbolic dispersion due to strong anisotropic electromagnetic response, resulting in applications such as surface wave manipulation and in-plane high-resolution imaging. A hyperbolic metasurface is classified as Type-II if it has a positive out-of-plane and a negative in-plane component for dielectric permittivity or magnetic permeability, respectively. In this work, we have realized a Type-II hyperbolic metasurface using a unit cell geometry. It showed Type-II hyperbolic behavior in response to in-plane polarized wave in the frequency range of 5.3 GHz-5.69 GHz. The proposed unit cell was arranged periodically in the x- and y-directions to form a structure similar to a plano-concave lens. Due to the hyperbolic dispersion, this planar structure focused incident in-plane polarized plane wavefronts at 5.4 GHz. Therefore, we expect to utilize the hyperbolic response of the proposed unit cell geometry to the in-plane polarized light for realizing planar focusing devices for integrated optical applications.