Dependency of the photonic band gaps in two-dimensional metallic photonic crystals on the shapes and orientations of rods

Abstract

Photonic bands in two types of two-dimensional metallic photonic crystals (2-D MPCs), which are composed of dielectric rods embedded into a metallic background (type I MPCs) and metallic rods in a dielectric background (type II MPCs), are investigated theoretically using a method based on the frequency-dependent plane-wave expansion method. We discuss the maximization of the normalized gap width as a function of the rod shapes and orientations. In addition, we study the effect of dielectric constants of the rods and the background on the width of the photonic band gap. Four different shapes of rods-square, circular, diamond, and rectangular-are considered. The numerical results show that the type I MPCs have a higher normalized gap width than the type II MPCs. We observe that the rotation of the noncircular rods in the type I MPCs leads to a slight variation, less than 10%, in the normalized values of the gap width in the two lattice structures. However, rotating the metallic square rods arranged in a square lattice results in doubling of the normalized gap width. The normalized gap width can be tailored by changing the dielectric constant of the rods (background) in type I (type II) MPCs.