Hyperbolic spoof plasmons in layered equivalent graphene metasurfaces

TL;DR

This paper introduces a novel microwave equivalent graphene concept using ultrathin plasmonic metasurfaces, enabling the design of hyperbolic metamaterials and devices with applications in nanoelectronics and optics.

Contribution

It proposes a new method to realize hyperbolic dispersion in microwave frequencies using layered equivalent graphene metasurfaces, validated through design, simulation, and experimental demonstration.

Findings

Successfully designed and experimentally verified hyperbolic metamaterials.

Demonstrated directional propagation and photonic spin Hall effect.

Achieved near-field resolution of 0.05λ with a hyperlens.

Abstract

Advances in graphene plasmonics offer numerous opportunities for enabling the design and manufacture of a variety of nanoelectronics and other exciting optical devices. However, due to the limitation of material properties, its operating frequency cannot drop to the microwave range. In this work, a new concept of microwave equivalent graphene based on the ultrathin monolayer plasmonic metasurface is proposed and demonstrated. Based on this concept, elliptical and hyperbolic dispersion can be theoretically obtained by stacking the equivalent graphene metasurfaces periodically. As proofs of the concept and method, an elliptical and an all-metal hyperbolic metamaterial are designed and numerically demonstrated. As a specified realization of the method, a practical hyperbolic metamaterial is fabricated and experimentally investigated with its validity verified by the directional propagation and photonic spin Hall effect. Furthermore, to investigate the validity of the method under extreme parameter conditions, a proof-of-concept hyperlens is designed and fabricated, with its near-field resolution of 0.05$\lambda$ experimentally verified. Based on the proposed concept, diverse optical graphene metamaterials such as focusing lens, dispersion-dependent directional couplers, and epsilon-near-zero materials can also be realized in the microwave regime.