An Efficient Approach to Identifying a Complete Photonic Band Gap in Two-dimensional Photonic Crystals with Omnidirectional Light Propagation

Abstract

Omnidirectional light propagation in two-dimensional (2D) photonic crystals (PCs) is investigated. An e-cient approach to identifying a complete photonic band gap (PBG) in 2D PCs has been developed. The in-plane band structure of 2D photonic crystals is calculated by an adaptive flnite element method. With adopting the suitable boundary conditions, the eigenvalues can be easily and rapidly calculated no matter how complex the geometric structures are. By symmetry, the omnidirectional photon density of states (PDOS) can be calculated based on the in-plane dispersion relation within the irreducible Brillouin zone. The PDOS corresponding to both the radiation and evanescent waves can be obtained accurately and e-ciently. We demonstrate that the \complete band gaps showed by some previous work due to considering only the radiation modes will be closed by including the contributions of the evanescent modes. These results are of general importance and relevant to the spontaneous emission by an atom, or to dipole radiation in two-dimensional periodic structures.