  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.
