Electrically-driven optical antennas enabled by mesoscopic contacts

Abstract

Electrically driven optical antennas are attracting much attention, in particular, due to necessity to develop integrated electrical source of surface plasmons for future plasmonic nanocircuitries. By default, this term denotes a metal nanostructure, in which electromagnetic oscillations at optical frequencies are excited by electrons, tunneling between metallic parts of the structure when a bias voltage is applied between them. Instead of relying on an inefficient inelastic light emission in a tunnel gap, we are suggesting to use ballistic nanoconstrictions as the feed element of an optical antennas in order to excite electromagnetic plasmonic modes. Similarly to tunneling structures, the voltage applied at the constriction falls over the contact of nanoscale length. Electron passing through the contact ballistically can gain the energy provided by the bias ~1eV and exchange it into an mode of the optical antenna. We discussed the underlying mechanisms responsible for the optical emission, and show that with nanoscale contact, one can reach quantum efficiency orders of magnitude larger than with standard tunneling structures.