High transmission in a metal-based photonic crystal

We propose metal-based photonic crystals (PCs) with annular air cavities. The unit cell could be analogue to a two-dimensional finite quantum well, which makes the PC system closely describe the similar physics of atomic crystals. By tuning the filling ratio of air annuluses, we discover a band inversion between monopolar and dipolar states (or similarly, the s and p states in quantum mechanics). There is a transition system of accidental degeneracy, where a Dirac-like cone could be achieved. Such design could be used to implement high transmission in a bulk metal near the frequency of the Dirac-like point. Numerical simulations are performed to investigate the wave transport behaviors of such a metallic system.