Absolute band gaps of a two-dimensional triangular-lattice dielectric photonic crystal with different shapes

Absolute band gaps of a two-dimensional triangular-lattice photonic crystal are calculated with the finite-difference time-domain method in this paper. Through calculating the photonic band structures of the triangular-lattice photonic crystal consisting of Ge rods immersed in air with different shapes, it is found that a large absolute band gap of 0.098 (2 c/a ) can be obtained for the structures with hollow triangular Ge rods immersed in air, corresponding to 19.8% of the middle frequency. The influence of the different factors on the width of the absolute band gaps is also discussed.