Photonic band structure and eigenmodes of magnetophotonic crystals

TL;DR

This paper investigates how magnetization affects the photonic band structure and eigenmodes of 2D and 3D magnetophotonic crystals, revealing complex polarization states and symmetry-breaking effects that enable new mode couplings.

Contribution

It introduces a plane wave expansion method to analyze magnetization effects on photonic crystals, highlighting the formation of exotic magnetic Bloch modes and their polarization properties.

Findings

Magnetization induces symmetry breaking and exotic Bloch modes.

Magnetic Bloch modes can be elliptically or circularly polarized.

Uncoupled states can become coupled in magnetic structures.

Abstract

We study photonic band structure of two- and three-dimensional magnetophotonic crystals and the polarization properties of their eigenmodes using a plane wave expansion method. The alteration of the photonic band structure and eigenmodes by magnetization are examined. Two orientations are studied: in-plane magnetization and perpendicular magnetization. The magnetization-induced symmetry breaking effects are shown to be responsible for the formation of exotic magnetic Bloch modes, comprised of two or more coupled symmetric and antisymmetric Bloch modes of the corresponding non-magnetic photonic crystal. These results imply that uncoupled states of non-magnetic photonic crystals can be excited, or become coupled, in magnetic structures. We show that the polarization state of magnetic Bloch modes is very complicated. In the particular case of perpendicular to plane magnetization they represent in-plane elliptically (or even circularly) polarized waves with large longitudinal component.