Design and optimization of 2D photonic crystals for the best absolute band gap

Two dimensional hexagonal lattice of central elliptical air holes are studied to exhibit a common band gap. The elliptical air holes are assumed to be surrounded by circular air holes in the hexagonal lattice. These circular air holes assumed to have small radii created in GaAs and are investigated by plane wave expansion method. In order to study how to achieve the best common photonic band gap, the central air holes are formed in the shapes of circles and ellipses with various radii and rotational angles. The results indicate that the best common band gap for both TE and TM polarizations are 94% at angles of ?=60° and ?=240° for elliptical air holes.