Limits for scattering resonances in azimuthally inhomogeneous nanotubes

Resonant electromagnetic scattering has been optimized for angularly inhomogeneous nanotubes characterized by different surface admittances along the two complementary arcs. The optimal designs are substantially more efficient compared to their best homogeneous counterparts and the spatial distribution of the scattering power reveals the nature of the sustained resonances. In this sense, the reported scattering scores constitute limits for the response of that simple class of structures and can be employed as optimized components in a wide spectrum of photonic devices from wave transformers and field sensors to electromagnetic filters and optical lenses.