Multifrequency transverse Faraday effect in single magneto-dielectric microspheres

We propose using a single magneto-dielectric microsphere as a device for enhancing the transverse Faraday effect at multiple wavelengths at the same time. Although the diameter of the sphere can be $<1$ $\mu$m, the numerically predicted strength of its magneto-optical (MO) response can be an order of magnitude stronger than in MO devices based on thick magnetic plates. The MO response of a microsphere is also comparable with that of subwavelength magneto-dielectric gratings which, however, operate at a single wavelength and occupy a large area. In contrast to gratings and thick plates, the compact size of the microsphere and its capability to support spin-wave excitations make it suitable for applications in nanophotonics, imaging systems, and magnonics.