engineering electromagnetic wave propagation in periodically layered gyromagnetic metamaterials with an external magnetic field

Tunable transmission characteristics of electromagnetic waves in periodically layered metamaterials (plmms), constructed by alternating dielectric layer and gyromagnetic layer such as yttrium-iron-garnet (yig), are investigated through an external magnetic field. based on transfer matrix method (tmm) and effective medium theory (emt), we compare the dispersion curves of te waves propagating in the plmms, and obtain the effective permeability and permittivity tensors of the homogenized gyromagnetic plmms by expanding the exact dispersion relation in long-wavelength limit. then, we calculate some propagating parameters when te waves incident on the plmms by emt in detail. numerical results show that the refraction state of te waves in the plmms can be dynamically changed between positive refraction state and cutoff state by controlling the external magnetic field. these exotic properties of gyromagnetic plmms have wide potential applications in many fields such as sub-wavelength all-optical switches and wave cutoff devices.