Topological Edge Plasmon Modes between Diatomic Chains of Nanoparticles

Understand

We study the topological edge plasmon modes between two "diatomic" chains of identical plasmonic nanoparticles.

• Zak phase for longitudinal plasmon modes in each chain is calculated analytically by solutions of macroscopic Maxwell's equations for particles in quasi-static dipole approximation.
• This approximation provides a direct analogy with the Su-Schrieffer-Heeger model such that the eigenvalue is mapped to the frequency dependent inverse-polarizability of the nanoparticles.
• The edge state frequency is found to be the same as the single-particle resonance frequency, which is insensitive to the separation distances within a unit cell.