Directional plasmonic nanoantennas for wireless links at the nanoscale

Optical nanoantennas are emerging as one of the key components in the future nanophotonic and plasmonic circuits. The first optical nanoantennas were in a form of simple spherical nanoparticles. Currently more complex Uda-Yagi nanoantenna structures were demonstrated. These nanoantennas enhance radiation of single emitters and provide well defined directional radiation. In this contribution we present the novel design of the directional nanoantenna, which is excited from the propagating mode of the plasmonic waveguide. The nanoantenna design is based on the travelling wave principle, well known at RF/microwave frequencies. By properly designing the propagating parts of the nanoantenna, a very efficient coupling to free space wave impedance can be achieved. Furthermore, the control over the radiation direction and beam width is relatively easy with this nanoantenna. Compared to the previously published Uda-Yagi designs, the new nanoantenna presented in this work has achieved a 3-fold improvement in the maximum value of directivity.