Understanding the Dispersion Diagrams of Two-Dimensional Supercells

This paper discusses the dispersion diagrams of holey periodic metasurfaces, which have been computed by analyzing either the primitive unit cell or a supercell of the structure. Particularly, the connection of the dispersion diagram of the supercell to the standard diagram of the primitive unit cell is investigated. The appearance of additional “anomalous” modes is explained and exemplified in the case of a rectangular supercell composed of two or three square unit cells.