Transmission properties of a two-dimensional photonic crystal in a dielectric constant supercell

Abstract

The photonic band gap of a two-dimensional triangular-lattice photonic crystal has been studied using the finite-difference time-domain method. The structure consists of two types of supercells: one with uniform dielectric rods and another with composite rods. Our results show that in both cases an enlarged band gap is present. The central frequency shifts to lower positions with a rise in the rod dielectric constant, but for the supercell with uniform dielectric rods, there are three smaller band gaps that cannot be formed into the enlarged one even when the dielectric constant reaches 57.5. For the photonic crystal of composite medium rods, the largest band gap appears when the dielectric constant reaches 36. Furthermore, the enlarged band gap is present when the dielectric constant decareases to 28. Our results show that the supercells play an important role in the formation of the enlarged photonic band gap. This work will be of significance in fabricating photonic crystal devices.