Enhanced emission and light control with tapered plasmonic nanoantennas

We introduce a design of Yagi-Uda plasmonic nanoantennas for enhancing the directive gain and achieving control over the angular emission of light. We demonstrate that tapering of nanoantenna elements allows to decrease the inter-element spacing tenfold also enhancing the emission directivity. We find the optimal tapering angle that provides the maximum directivity enhancement and the minimum end-fire beamwidth.