Unidirectional Emission of a Quantum Dot Coupled to a Nanoantenna

TLDR

Nanoscale quantum emitters are essential for quantum optics and sensing, yet their omnidirectional light interaction requires large solid angles for efficient excitation and detection. The study demonstrates unidirectional emission from a single emitter by coupling it to a nanofabricated Yagi‑Uda antenna. The quantum dot is positioned in the antenna’s near field to drive its resonant feed element. The coupled system produces strongly polarized, highly directional luminescence that can be tuned by antenna dimensions, illustrating optical antennas’ potential to mediate energy exchange among nano‑emitters.

Abstract

Nanoscale quantum emitters are key elements in quantum optics and sensing. However, efficient optical excitation and detection of such emitters involves large solid angles because their interaction with freely propagating light is omnidirectional. Here, we present unidirectional emission of a single emitter by coupling to a nanofabricated Yagi-Uda antenna. A quantum dot is placed in the near field of the antenna so that it drives the resonant feed element of the antenna. The resulting quantum-dot luminescence is strongly polarized and highly directed into a narrow forward angular cone. The directionality of the quantum dot can be controlled by tuning the antenna dimensions. Our results show the potential of optical antennas to communicate energy to, from, and between nano-emitters.