Gradient metasurfaces have been extensively used in the past few years for advanced wave manipulation over a thin surface. These metasurfaces have been mostly designed based on the generalized laws of reflection and refraction. However, it was recently revealed that metasurfaces based on this approach tend to suffer from inefficiencies and complex design requirements. We have recently proposed a different approach to the problem of efficient beam steering using a surface, based on bianisotropic particles in a periodic array. Here, we show highly efficient reflective metasurfaces formed by pairs of isotropic dielectric rods, which can offer asymmetrical scattering of normally incident beams with unitary efficiency. Our theory shows that moderately broadband anomalous reflection can be achieved with suitably designed periodic arrays of isotropic nanoparticles. We also demonstrate practical designs using ${\mathrm{TiO}}_2$ cylindrical nanorods to deflect normally incident light toward a desired direction. The proposed structures may pave the way to a broader range of light management opportunities, with applications in energy harvesting, signaling, and communications.

• Received 31 May 2017

DOI:https://doi.org/10.1103/PhysRevB.96.075432