All-Dielectric Cylindrical Metasurfaces for Enhanced Directional Scattering

We present a detailed analytical and numerical study of cylindrical metasurfaces for enhanced scattering applications. Analytical expressions are derived for the surface impedances of single and double metasurface configurations, respectively, which are required to maximize scattering in the forward direction. A surface impedance model is developed for 1-D arrays of dielectric cylinders that is subsequently used to realize and implement numerically the required surface impedances. Our analytical and full-wave numerical results reveal that cylindrical all-dielectric metasurfaces may exhibit superior forward scattering and balanced higher-order mode excitation in comparison to traditional solid dielectric resonators. Two examples, both with silicon dielectric cylinder, have been chosen to showcase our results, and they were found to exhibit extraordinary directional scattering properties with the respective forward scattering efficiencies being 9 and 19 times that of a single mode resonator. The choice of silicon for the cylinder dielectrics highlights the potential of the proposed configuration in optical communications, although the presented theory applies across the other parts of the electromagnetic spectrum.