Flat Bands and Surface States in Two-Dimensional Metallic Photonic Crystals

Metallic photonic crystals provide very interesting properties such as flat bands for one polarisation. We investigate these modes by calculating the eigenvalues and by deriving the local density of states of the structure. These flat bands are well known as surface resonances which have been investigated in literature for non-realistic material parameter so far. It is shown that appropriate geometry and low damping play a crucial role for the occurrence of flat bands. In order to demonstrate this we compare a loss-less Drude model, a lossy Drude model (used frequently in the literature) and a model based on measured data of silver, which is known to have low loss (compared to other metals). For these models we provide the local density of states, investigate the complex eigenvalues in the flat band region and study reflection and transmission of finite metallic photonic crystal slabs.