Spatially Inhomogeneous Non-Hermitian Topological Metasurfaces

Abstract

Non-Hermitian physics provides a powerful route for controlling wave propagation in open systems, yet its role in spatially inhomogeneous topological structures remains insufficiently clarified. Here, we experimentally demonstrate a spatially inhomogeneous non-Hermitian topological metasurface on a microwave microstrip platform. A continuous geometric modulation introduces a position-dependent Dirac mass and forms a mass-domain-wall interface, while lumped resistive loading provides a controllable imaginary potential. This design transforms the conventional Hermitian degeneracy into a real-part degenerate region near the Γ point, accompanied by an imaginary-frequency bifurcation and mode-dependent attenuation. Tight-binding calculations, full-wave simulations, and microwave near-field measurements are used to characterize the complex bulk dispersion and lossy edge-state transport. We further show that the edge modes exhibit pseudospin-momentum-locked directional excitation, with non-Hermiticity providing an additional degree of freedom for attenuation and mode selectivity. These results clarify the distinct roles of geometric mass gradients and engineered dissipation, establishing a tunable microwave platform for loss-engineered topological wave transport.

Keywords

topological metasurfaces / non-Hermitian systems / chiral edge states / inhomogeneous lattices / complex band structures

RIGHTS & PERMISSIONS

Higher Education Press 2026

Just Accepted

This article has successfully passed peer review and final editorial review, and will soon enter typesetting, proofreading and other publishing processes. The currently displayed version is the accepted final manuscript. The officially published version will be updated with format, DOI and citation information upon launch. We recommend that you pay attention to subsequent journal notifications and preferentially cite the officially published version. Thank you for your support and cooperation.