The effects of retardation on the topological plasmonic chain: plasmonic edge states beyond the quasistatic limit

TL;DR

This paper investigates how retardation effects influence topological edge states in a plasmonic nanoparticle chain, revealing the persistence of topological features and potential for robust nanophotonic applications.

Contribution

It extends the topological plasmonic chain model by including retardation and damping, demonstrating the robustness of topological edge states under realistic conditions.

Findings

Topological edge states persist with retardation effects.

Quantized Zak phase remains due to chiral symmetry.

Potential for disorder-robust nanophotonic hotspots.

Abstract

We study a one-dimensional plasmonic system with non-trivial topology: a chain of metallic nanoparticles with alternating spacing, which is the plasmonic analogue to the Su-Schreiffer-Heeger model. We extend previous efforts by including long range hopping with retardation and radiative damping, which leads to a non-Hermitian Hamiltonian with frequency dependence. We calculate band structures numerically and show that topological features such as quantised Zak phase persist due to chiral symmetry. This predicts parameters leading to topologically protected edge modes, which allows for positioning of disorder-robust hotspots at topological interfaces, opening up novel nanophotonics applications.