Magneto-optics in bi-gyrotropic garnet wavequide

In many works, the magneto-optical effects for optical frequencies are normally described by using an electric dipole approximation. Nevertheless, this approximation is problematic in far infrared region and for ultrathin filmsin the optical band. For this reason, dispersion relations have been derived for quided modes in a monolayer system at transverse geometry with bi-gyrotropic anisotropy on the base of matrix elements. The permeability tensor effect on wavequiding is analysed in detail. Experimental possibilities of the dark mode spectroscopy for permeability tensor study in mentioned structures are briefly discussed.