Complete bandgap in two dimensional photonic crystals with square bravais lattice

Two- dimensional (2-D) photonic crystals (PhCs) of square lattice have been investigated to find the complete photonic bandgap. Band diagram calculations have been performed using the simulator "PWE band solver" of the software package optiFDTD™, based on plane wave expansion method. GaAs dielectric rods in air background with four different shapes have been considered. Filling fraction, rod/air hole orientation angle and material dielectric constant have been varied. It has been found that PhCs with square dielectric rods have the largest gap; the gap-midgap ratio is 5.39% when filling fraction f = 0.47 and orientation angle θ = 0°. It has also been found that the photonic band gap behavior for other types of material e.g. Si, Ge are similar to the GaAs and these materials can exhibit complete photonic band gap.