The dyadic Green's function of the inhomogeneous vector Helmholtz equation
describes the field pattern of a single frequency point source. It appears in
the mathematical description of many areas of electromagnetism and optics
including both classical and quantum, linear and nonlinear optics, dispersion
forces (such as the Casimir and Casimir-Polder forces) and in the dynamics of
trapped atoms and molecules. Here, we compute the Green's function for a
layered topological insulator. Via the magnetoelectric effect, topological
insulators are able to mix the electric, E, and magnetic induction, B, fields
and, hence, one finds that the TE and TM polarizations mix on reflection
from/transmission through an interface. This leads to novel field patterns
close to the surface of a topological insulator.Comment: 16 pages, 9 figure
