Controllable directive radiation of a circularly polarized dipole above planar metal surface

We report unidirectional radiation of a circularly polarized dipole above planar metal surface, the radiation direction can be manipulated via changing the distance between the dipole and the surface. This phenomenon is unique for the combination of circularly polarized dipole and metal surface and does not happen for linearly polarized dipole on metal surface or circularly polarized dipole on dielectric surface. The underlying physics is analytically disclosed by the interference of two orthogonally-oriented dipole component with π/2 phase lag. A substantially different mechanism of introducing the vectorial nature of the dipole itself to control light emission distinguishes the present scheme from nanoantenna and provides a new degree of freedom in light emission engineering.