Unidirectional edge modes in time-modulated metamaterials

TL;DR

This paper demonstrates the theoretical and numerical realization of unidirectional edge modes in time-modulated supercell metamaterials, enabling edge-specific wave localization through symmetry-breaking time modulation.

Contribution

It introduces a novel method to achieve unidirectional edge modes in time-modulated structures by breaking symmetry in supercell metamaterials, supported by analytical and numerical analysis.

Findings

Edge modes are localized at one edge of the structure.

Time modulation splits degenerate eigenspaces into unidirectional modes.

Edge modes remain stable under fluctuations in modulation amplitude.

Abstract

We prove the possibility of achieving unidirectional edge modes in time-modulated supercell structures. Such finite structures consist of two trimers repeated periodically. Because of their symmetry, they admit degenerate edge eigenspaces. When the trimers are time-modulated with two opposite orientations, the degenerate eigenspace splits into two one-dimensional eigenspaces described by an analytical formula, each corresponds to a mode which is localized at one edge of the structure. Our results on the localization and stability of these edge modes with respect to fluctuations in the time-modulation amplitude are illustrated by several numerical simulations.