Transient analysis of spectrally asymmetric magnetic photonic crystals with ferromagnetic losses

We analyze transient electromagnetic pulse propagation in spectrally asymmetric magnetic photonic crystals MPCs with ferromagnetic losses. MPCs are dispersion-engineered materials consisting of a periodic arrangement of misaligned anisotropic dielectric and ferromagnetic layers that exhibit a stationary inflection point in the asymmetric dispersion diagram and unidirectional frozen modes. The analysis is performed via a late-time stable finite-difference time-domain method FDTD implemented with perfectly matched layer PML absorbing boundary conditions, and extended to handle simultaneously dispersive and anisotropic media. The proposed PML-FDTD algorithm is based on a D-H and B-E combined field approach that naturally decouples the FDTD update into two steps, one involving the anisotropic and dispersive constitutive material tensors and the other involving Maxwell’s equations in a complex coordinate space to incorporate the PML . For ferromagnetic layers, a fully dispersive modeling of the permeability tensor is implemented to include magnetic losses in a consistent fashion. The numerical results illustrate some striking properties of MPCs, such as wave slowdown frozen modes , amplitude increase pulse compression , and unidirectional characteristics. The numerical model is also used to investigate the sensitivity of the MPC response against excitation frequency and bandwidth , material ferromagnetic losses , and geometric layer misalignment and thickness parameter variations.