Magnetic Photonic Crystals as Artificial Magnetoelectrics

Abstract

Magnetic photonic crystals are spatially periodic dielectric composites with at least one of the constitutive components being a magnetically polarized material. We show that the electrodynamic properties of magnetic photonic crystals with proper configuration correspond to those of hypothetical media with huge linear magnetoelectric effect. In particular, such composites can display strong asymmetry ω(k) ≠ ω(-k) of the electromagnetic dispersion relation, which can result in a number of interesting phenomena, including the electromagnetic unidirectionality. A unidirectional medium, being perfectly transmissive for electromagnetic wave of certain frequency, freezes the radiation of the same frequency propagating in the opposite direction in the form of a coherent standing wave with zero group velocity. At microwave frequencies, unidirectional photonic crystals can be made of common ferro- or ferrimagnetic materials alternated with anisotropic dielectric layers.