PBG structures of novel two-dimensional annular photonic crystals with triangular lattice

Abstract

The photonic band gap (PBG) structures of four types of annular photonic crystals (PCs) with inner-scatter of rectangular, square, hexagonal and circle shapes are respectively calculated by the plane wave expansion method. The optimal samples with the largest gap-midgap ratio for each structure are obtained by scanning the four parameters: filling ratio f, dielectric constant ɛ1, rotating angle θ of inner-scatters and outside radius R of the air ring. The results show that the band gap can be further maximized by adjusting the structural parameters, and a wide PBG with the gap-midgap ratio of 20.4% is gained in the annular photonic crystal with rectangular inner-scatters.