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

• Published in: Scientific reports Vol. 7; no. 1; p. 43115
• Main Author: Crosse, J. A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 21.02.2017; Nature Publishing Group
• Subjects: 639/766/1130/2799; 639/766/119/2792; Electric fields; Electromagnetic radiation; Geometry; Humanities and Social Sciences; Magnetic fields; multidisciplinary; Polarization; Radiation; Science; Symmetry
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep43115

Topological insulators subject to a time-reversal-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 an incident plane-polarized electromagnetic wave normal to a multilayered structure. Here we show, theoretically and numerically, that by using a waveguide geometry with a topological insulator guide layer and magneto-dielectric cladding it is possible to achieve rotations of ≈100 mrad and generate an elliptical polarization with only a three-layered structure. 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 electromagnetic radiation.