Propagation of surface plasmons on plasmonic Bragg gratings

Abstract

We use coupled-mode theory to describe the scattering of a surface-plasmon polariton (SPP) from a square wave grating (Bragg grating) of finite extension written on the surface of either a metal-dielectric interface or a dielectric-dielectric interface covered with a patterned graphene sheet. We find analytical solutions for the reflectance and transmittance of SPP's when only two modes (forward-and back-scattered) are considered. We show that in both cases the reflectance spectrum presents stop-bands where the SPP is completely back-scattered, if the grating is not too shallow. In addition, the reflectance coefficient shows Fabry-Pérot oscillations when the frequency of the SPP is out of the stop-band region. For a single dielectric well, we show that there are frequencies of transmission equal to 1. We also provide simple analytical expression for the different quantities in the electrostatic limit.

Emergent non-Hermitian edge polarisation in an Hermitian tight-binding model

“…Our result shows that edge polarisation alone is not sufficient as an experimental diagnostic of non-Hermitian topology since it can equally appear in Hermitian problems as the one discussed here. This is particularly crucial for, e.g., plasmons in metal gratings or nanoparticle arrays, one of the possible test-beds of non-Hermitian topology, and to which the present model applies 47,63,64 .…”

Tunable plasmonic resonator using conductivity modulated Bragg reflectors

“…Therefore, as it is apparent from the above derivation, to solve this scattering problem, we have to solve for P(q). To do this, we can either use numerical methods to solve the difficult integrals involved using a discretized mesh as explained in [52] or alternatively use an analytical method with further approximations to simplify the design, similar to what is presented in [55]. In this paper, we use the FEM which is the most extensively utilized simulation approach to numerically solve for the R, T and S coefficients.…”