FEM analysis of frozen mode regime inside chirped MPCs

Magnetic photonic crystals (MPCs) with interesting spectral properties can be fabricated using repeated unit cells composed of two layers of anisotropic dielectrics and a layer of gyrotropic ferrite. The frozen mode regime of a layered MPC is analytically predicted to be a narrow bandwidth phenomenon. The frequency domain finite element method (FDFEM) is used to demonstrate the effect of unit cell chirping on the ω-β relationship, demonstrating a constant, small group velocity over a nonzero bandwidth. The finite element time domain (FETD) method is used to demonstrate pulses which are unable to propagate cohesively in unchirped MPCs. In contrast, these pulses are able to propagate cohesively in chirped MPCs which are less dispersive. The cost of the increased bandwidth is a reduction in pulse amplitude inside the MPC and a nonzero frozen mode velocity.