Low-symmetry magnetic photonic crystals for nonreciprocal and unidirectional devices.

We develop an exact theory for light propagation in transversely-magnetized low-symmetry magnetic photonic crystals. We investigate the nature of nonreciprocal dispersion and unidirectionality in these systems and show that it is associated with boundary effects rather than propagation. We calculate the nonreciprocal response of finite structures and propose an asymmetric magneto-optical cavity as a practical building block for one-way optical components.