The effects of three-dimensional defects on one-way surface plasmon propagation for photonic topological insulators comprised of continuous media

TL;DR

This paper explores how three-dimensional defects affect one-way surface plasmon propagation in photonic topological insulators made of continuous media, revealing the impact of defects and losses on topologically protected modes.

Contribution

It analytically demonstrates the topological nature of TM modes in continuous magneto-plasma media and investigates the effects of 3D defects and metal losses on surface plasmon propagation.

Findings

Side scattering occurs due to 3D defects, affecting mode propagation.

Topologically protected modes are robust against backward reflection.

Waveguide geometries can mitigate side-scattering effects.

Abstract

We have investigated the one-way surface plasmon-polariton (SPP) at the interface of a continuous magneto-plasma material and metal. We demonstrated that TM modes inside a continuous material can be assigned non-trivial Chern numbers analogous to those of topological photonic crystals; moreover these Chern numbers can be calculated analytically. This leads to the appearance of topologically protected surface modes propagating at frequencies inside the bandgap of the magneto-plasma. Previous works considered 2D structures; here we consider the effects of 3D defects, and show that, although backward propagation/reflection cannot occur, side scattering does take place and it has significant effect on the propagation of the surface mode. Several different waveguiding geometries are considered for reducing the effects of side-scattering, and we also consider the effects of metal loss.