Nature of the photonic band gap: some insights from a field analysis

To clarify the nature of photonic band gaps, a series of calculations on two-dimensional photonic crystals is undertaken. Systems that possess a large gap for one polarization and no gap for the other polarization are analyzed. Two features of a photonic crystal that give rise to a large photonic band gap for each polarization, i.e., connectivity and concentration of the dielectric material, are elucidated. The implications for making materials with large photonic band gaps in two and three dimensions are discussed.