Surface-Wave Propagation on Non-Hermitian Metasurfaces with Extreme Anisotropy

TL;DR

This paper investigates non-Hermitian metasurfaces with extreme anisotropy induced by spatially modulated gain and loss, revealing novel surface-wave propagation effects with potential applications in imaging, sensing, and communications.

Contribution

It introduces a new class of non-Hermitian metasurfaces leveraging gain-loss interplay to achieve extreme anisotropy and unconventional surface-wave control.

Findings

Demonstrates surface-wave canalization due to gain-loss modulation.

Reveals nonlocal effects and departures from ideal conditions.

Shows feasibility of the required parameters for practical implementation.

Abstract

Electromagnetic metasurfaces enable the advanced control of surface-wave propagation by spatially tailoring the local surface reactance. Interestingly, tailoring the surface resistance distribution in space provides new, largely unexplored degrees of freedom. Here, we show that suitable spatial modulations of the surface resistance between positive (i.e., loss) and negative (i.e., gain) values can induce peculiar dispersion effects, far beyond a mere compensation. Taking inspiration from the parity-time symmetry concept in quantum physics, we put forward and explore a class of non-Hermitian metasurfaces that may exhibit extreme anisotropy mainly induced by the gain-loss interplay. Via analytical modeling and full-wave numerical simulations, we illustrate the associated phenomenon of surface-wave canalization, explore nonlocal effects and possible departures from the ideal conditions, and address the feasibility of the required constitutive parameters. Our results suggest intriguing possibilities to dynamically reconfigure the surface-wave propagation, and are of potential interest for applications to imaging, sensing and communications.