  In the context of $\theta$ electrodynamics we find transverse electromagnetic
wave solutions forbidden in Maxwell electrodynamics. Our results attest to new
evidence of the topological magnetoelectric effect in topological insulators,
resulting from a polarization rotation of an external electromagnetic field.
Unlike Faraday and Kerr rotations, the effect does not rely on a longitudinal
magnetic field, the reflected field, or birefringence. The rotation occurs due
to transversal discontinuities of the topological magnetoelectric parameter in
cylindrical geometries. The dispersion relation is linear, and birefringence is
absent. One solution behaves as an optical fiber confining exact transverse
electromagnetic fields with omnidirectional reflectivity. These results may
open new possibilities in optics and photonics by utilizing topological
insulators to manipulate light.
