Optical modes in slab waveguides with magnetoelectric effect

TL;DR

This paper analytically investigates optical modes in anisotropic slab waveguides with magnetoelectric effects, deriving characteristic equations and exploring mode formation, hybridization, and transitions between photonic and plasmonic modes.

Contribution

It introduces a vector-potential approach with a generalized Lorentz gauge to derive closed-form characteristic equations for complex modes in magnetoelectric slab waveguides.

Findings

Complex modes and hybridization are inevitable in such waveguides.

Hyperbolic dispersion leads to a transition from photonic to plasmonic modes.

Analytical dispersion diagrams are provided for various waveguide configurations.

Abstract

Optical modes in anisotropic slab waveguides with topological and chiral magnetoelectric effects are investigated analytically, by deriving the closed-form characteristic equations of the modes and hence computing the dispersion-diagrams. In order to compute the characteristic equations, a vector-potential approach is introduced by incorporating a generalized Lorentz gauge, and the corresponding Helmholtz equations are derived correspondingly. It will be shown that the formation of the complex modes and hybridization of the optical modes in such slab waveguides is inevitable. Moreover, when the tensorial form of the permittivity in the waveguide allows for a hyperbolic dispersion, complex transition from the photonic kinds of modes to the plasmonic modes is expected.