The absolute photonic band gaps and all-angle negative refraction phenomenon of two-dimensional photonic crystals composed of multi-ring scatterers

A new novel of scatterers which is in the form of a multi-ring shape is proposed in this paper. The circular scatterers in the two-dimensional (2D) photonic crystals (PCs) have been replaced by the multi-ring ones based on the honeycomb and Kagomé lattices, and the effects of the number of layers (N), the refractive index (n), and the ring width (W) for the multi-ring scatterers on the photonic band gaps (PBGs) are also researched. After that, the relative properties of the absolute PBGs and all-angle negative refraction (AANR) phenomenon in two different types of inserted scatterers have been probed into. The band structure diagrams of those two lattices and equifrequency contours (EFCs) for two different inserted scatterers are acquired through the plane wave expansion (PWE) method. Through comparison, it is qualified for being figured out that, if the scatterer structure is varied from circular rode to multi-ring one, the bandwidths of some absolute PBGs can be expanded or the number of absolute PBGs can be added. Then, through the diagrams of EFCs and the band structures, the phenomenon that the AANR range shrank after the change has been discovered, and verify it by calculation.