A two-dimensional photonic crystal with six large bandgaps formed by a hexagonal lattice of anisotropic cylinders
A two—dimensional photonic crystal with six large bandgaps formed by a hexagonal lattice of anisotropic cylinders

The plane-wave expansion method is used to calculate the band structure of a two-dimensional photonic crystal formed by a hexagonal structure of anisotropic cylinders. Two cylindrical inclusions in the unit cell have two different radii, R1 and R2 (R12). By reducing the symmetry of the structure and choosing appropriately parameters R2 and s=R1/R2 (s<1), we obtain six large complete bandgaps, among which three are over 0.05 ωe (where ωe=\frac{2πc}{a}) in the high region of the normalized frequency (however, one of these over 0.065 ωe is not stable). There are two other stable complete bandgaps in the low-frequency region.