Nonreciprocal magnetic photonic crystals

Abstract

We study band dispersion relations $\omega \left(\overrightarrow{k}\right)$ of a photonic crystal with at least one of the constitutive components being a magnetically ordered material. It is shown that by proper spatial arrangement of magnetic and dielectric components one can construct a magnetic photonic crystal with strong spectral asymmetry (nonreciprocity) $\omega \left(\overrightarrow{k}\right)\ne \omega \left(-\overrightarrow{k}\right).\mathrm{}$ The spectral asymmetry, in turn, results in a number of interesting phenomena, in particular, one-way transparency when the magnetic photonic crystal, being perfectly transparent for a Bloch wave of frequency Ω, “freezes” the radiation of the same frequency Ω propagating in the opposite direction. The frozen radiation corresponds to a Bloch wave with zero group velocity $\partial \omega \mathrm{}\left(k\right)/\partial k=0\mathrm{}$ and, in addition, with ${\partial }^2\omega \mathrm{}\left(k\right)/\partial k^2=0.\mathrm{}$