  Optical field interacting with a topologically protected one-dimensional
helical state is shown to support a one-dimensional plasmon-polariton that is
characterized by a non-linear dispersion. In a two-dimensional Dirac magnet
these electro-optical excitations are confined to domain walls, thus, offering
a possibility to manipulate quantum optical states by altering magnetic domain
configurations. An exact spectral equation for such a topological
plasmon-polariton is derived.
