Investigation of photonic band gaps in triangular lattices of metallic square rods in dielectric background

We studied, by using a modified plane-wave method, the band gap properties of two-dimensional metallodielectric photonic crystals with triangular lattice of square rods embedded into backgrounds with different dielectric constants. The existence of absolute photonic band gaps in the TM polarization and the dependence of their width as a function of the background dielectric constant and the filling fraction has been investigated. The background dielectric constant has been varied between 1 and 12 and the filling fraction from 0.01 to the close packed condition. We have found that the minimum background dielectric constant necessary to open an absolute photonic band gap is 1.6. The results show the possibility to achieve a relative band gap width larger than 10% for filling fractions away from the close packed condition for different backgrounds.