  Exotic topological and transport properties of Weyl semimetals generated a
lot of excitement in the condensed matter community. Here we show that Weyl
semimetals in a strong magnetic field are highly unusual optical materials. The
propagation of electromagnetic waves is affected by an interplay between
plasmonic response of chiral Weyl fermions and extreme anisotropy induced by a
magnetic field. The resulting magneto-polaritons possess a number of peculiar
properties, such as hyperbolic dispersion, photonic stop bands,
coupling-induced transparency, and broadband polarization conversion. These
effects can be used for optical spectroscopy of these materials including
detection of the chiral anomaly, or for broadband terahertz/infrared
applications.
