Large omnidirectional band gaps in metallodielectric photonic crystals

Using a finite-difference time-domain method, we study the band-structure and transmission properties of three-dimensional metallodielectric photonic crystals. The metallodielectric crystals are modeled as perfect electrical conducting objects embedded in dielectric media. We investigate two different lattice geometries: the face-centered-cubic (fee) lattice and the diamond lattice. Partial gaps are predicted in the fee lattice, in excellent agreement with recent experiments. Complete gaps are found in a diamond lattice of isolated metal spheres. The gaps appear between the second and third bands and their sizes can be larger than 60% when the radius of the spheres exceeds 21% of the cubic unit cell size. A possible fabrication scheme for this structure is proposed and transmission calculations are performed.