  The propagation of light in Weyl semimetal films is analyzed. The magnetic
family of these materials is known by anomalous Hall effect, which, being
enhanced by the large Berry curvature, allows one to create strong gyrotropic
and nonreciprocity effects without external magnetic field. The existence of
nonreciprocal waveguide electromagnetic modes in ferromagnetic Weyl semimetal
films in the Voigt configuration is predicted. Thanks to the strong dielectric
response caused by the gapless Weyl spectrum and the large Berry curvature,
ferromagnetic Weyl semimetals combine the best waveguide properties of magnetic
dielectrics or semiconductors with strong anomalous Hall effect in
ferromagnets. The magnitude of the nonreciprocity depends both on the internal
Weyl semimetal properties, the separation of Weyl nodes, and the external
factor, the optical contrast between the media surrounding the film. By tuning
the Fermi level in Weyl semimetals, one can vary the operation frequencies of
the waveguide modes in THz and mid-IR ranges. Our findings pave the way to the
design of compact, tunable, and effective nonreciprocal optical elements.
