Theory of topological insulator waveguides: polarization control and the enhancement of the magneto-electric effect

Abstract

Topological insulators subject to a time-symmetry-breaking perturbation are predicted to display a magneto-electric effect that causes the electric and magnetic induction fields to mix at the material's surface. This effect induces polarization rotations of between ~1-10 mrad per interface in incident plane-polarized light normal to a multilayered structure. Here we show, theoretically and numerically, that, using a waveguide geometry with a topological insulator guide layer and dielectric cladding, it is possible to achieve rotations of between ~100-1000 mrad and generate an elliptical polarization with only a three-layered structure. Both the rotation angle and ellipticity are dependent on the permittivity contrast of the guide and cladding layers and the strength of the time-symmetry-breaking perturbation. This geometry is beneficial, not only as a way to enhance the magneto-electric effect, rendering it easier to observe, but also as a method for controlling the polarization of light in the next generation of photonic devices.

7 Pages, 3 figures (with supplementary information 5 Pages)

References in corpus (5)

• Topological Insulators with Inversion Symmetry
• A topological Dirac insulator in a quantum spin Hall phase : Experimental observation of first strong topological insulator
• Topological Field Theory of Time-Reversal Invariant Insulators
• The Electromagnetic Green's Function for Layered Topological Insulators
• Optical properties of topological insulator Bragg gratings: Faraday rotation enhancement for TM polarized light at large incidence angles