On Certain Design Criteria for Nanoantennas in the Visible

Here, we report our recent results on the modeling and design of optical nanoantennas loaded with optical nanocircuit elements. In particular, we review our recently proposed concepts of optical nanoantenna input impedance, optical radiation resistance, matching and loading using optical lumped nanocircuit elements, specifically as applied to plasmonic nanodipoles, both in transmitting and receiving modes. We analyze in details the radiation properties of this class of optical nanoantennas and we discuss how the concepts of optical nanocircuits may allow tuning and better matching these nanoradiators when fed by optical waveguides.