PML-FDTD Analysis of Nonreciprocal Magnetic Photonic Crystals with Ferromagnetic Losses

Nonreciprocal magnetic photonic crystals (MPCs) are dispersion engineered metamaterials that exhibit unique properties such as electromagnetic unidirectionality and frozen modes with zero group velocity [1], [2]. Nonreciprocal MPCs are periodic structures composed of misaligned anisotropic dielectric layers (A-layers) and ferromagnetic layers (F-layers), as shown in Fig. 1. MPCs with a proper choice of geometry and tensor parameters can display asymmetric dispersion relation ω(k) with a stationary inflection point (SIP) in a forward direction and no SIP in a backward direction [1]. Since group velocities are extremely low near the SIP, EM waves seem to be “frozen” inside nonreciprocal MPCs in the forward direction; at the same time, forward propagating EM pulses can exhibit a dramatic growth in amplitude inside the MPC. In the backward direction, EM waves inside the MPCs propagate in an ordinary fashion [2].