Collectively Driven Optical Nanoantennas

TL;DR

This paper demonstrates how coherent excitation of optical nanoantennas can be used to control their properties, such as directivity and efficiency, by leveraging collective quantum states, thus enhancing nanophotonic device performance.

Contribution

It introduces the concept of using the collective phase of quantum emitters to actively control nanoantenna behavior, supported by numerical and quantum modeling.

Findings

Coherent excitation enables control over antenna multipoles.

Enhanced directivity and efficiency observed with collective states.

Quantum phase manipulation improves nanoantenna performance.

Abstract

Optical nanoantennas, i.e., elements transforming localized light or waveguide modes into freely propagating fields and vice versa, are vital components for modern nanophotonics. Optical antennas have been demonstrated to cause the Dicke superradiance effect, i.e., collective spontaneous emission of quantum sources. However, the impact of coherent excitation on the antenna performance, such as directivity, efficiency, and Purcell effect, remains mostly unexplored. Herein, using full-wave numerical simulations backed by a quantum model, we unveil that coherent excitation allows controlling antenna multipoles, on-demand excitation of nonradiative states, enhanced directivity and improves antenna radiation efficiency. This collective excitation corresponds to the states with nonzero dipole moment in the quantum picture, where the quantum phase is well defined. The results of this work bring another degree of freedom - the collective phase of an ensemble of quantum emitters - to control optical nanoantennas and, as such, pave the way to the use of collective excitations for nanophotonic devices with superb performance. To make the discussion independent of the frequency range, we consider the all-dielectric design and use dimensionless units.