Complex response and polariton-like dispersion splitting in periodic metal nanoparticle chains

TL;DR

This paper reveals complex dispersion relations and polariton-like splitting in metal nanoparticle chains, showing potential for tunable, localized energy distributions with long loss lengths below the light line.

Contribution

It demonstrates the complex dispersion and anticrossing behavior in metal nanoparticle chains, highlighting the potential for tunable energy localization and long-range signal guiding.

Findings

Dispersion relation splits into two anticrossing branches due to retardation.

Longer-than-expected loss lengths are observed below the light line.

Localized energy distributions can be tuned via illumination wavelength.

Abstract

We show that guiding of optical signals in chains of metal nanoparticles is subject to a surprisingly complex dispersion relation. Retardation causes the dispersion relation to split in two anticrossing branches, as common for polaritons. While huge radiation losses occur above the light line, just below the light line the micron-sized loss lengths are much longer than expected. The anticrossing allows to create highly localized energy distributions in finite arrays that can be tuned via the illumination wavelength. Our results apply to all linear chains of coupled resonant scatterers.