Large absolute band gaps in two-dimensional photonic crystals formed by large dielectric pixels

Large absolute band gaps are searched among photonic crystals whose unit cells are formed by large dielectric pixels. To speed up the computation, a fast plane-wave expansion method is introduced for calculating the band structures for such special photonic crystals. Two structures are found to have absolute band gaps of 0.1158(2πc/a) and 0.11(2πc/a) $(a$ is the period of the square lattice) at the low- and high-frequency regions, respectively. Both structures are stable and convenient for fabrication.