The Nonlinear Limit of Babinet's Principle

The well–known Babinet principle states that the diffraction pattern of an opaque body is identical to that of a complementary hole in an opaque screen. It is strictly valid for idealized media and is applicable to plasmonic nanostructures. A conceptual sketch is shown in Figure 1a comparing a gold nanorod with a nanoslit in a gold plane on their simulated far-field image. The principle is thus a powerful tool for predicting the scattering behavior of structures where the solution for the complementary structure is already known. This makes it very useful for the design of aperture antennas or metamaterials.