Unidirectional ultracompact DNA-templated optical antennas

TL;DR

This paper introduces DNA-templated ultracompact optical antennas that are capable of directing single-molecule fluorescence emission in predefined directions at sub-wavelength scales, using DNA origami to assemble gold nanorods.

Contribution

It presents a novel, ultracompact, DNA-based design for optical antennas that achieve directional emission with simple, sub-wavelength structures.

Findings

Demonstrated unidirectional fluorescence emission from a single molecule

Achieved precise assembly of gold nanorods with 5 nm gap using DNA origami

Showed control of emission directionality with simple nanostructures

Abstract

Optical nanoantennas are structures designed to manipulate light-matter interactions at the nanoscale by interfacing propagating light with localized optical fields. In recent years, a plethora of devices have been realized that are able to efficiently tailor the absorption and/or emission rates of fluorophores. By contrast, modifying the spatial characteristics of their radiation fields remains a challenge. Up to date, the designs providing directionality to fluorescence emission have required compound, complex geometries with overall dimensions comparable to the operating wavelength. Here, we present the fabrication and characterization of DNA-templated ultracompact optical antennas, with sub-wavelength sizes and capable of directing single-molecule fluorescence into predefined directions. Using the DNA origami methodology, two gold nanorods are assembled side-to-side with a separation gap of 5 nm. We show that a single fluorescent molecule placed at the tip of one of the nanorods drives the dimer antenna in anti-phase, leading to unidirectional emission.