Color Routing and Beam Steering of Single-Molecule Emission with a Spherical Silicon Nanoantenna

TL;DR

This paper demonstrates how a single silicon nanosphere can be used to control the direction and color of emission from single molecules, achieving high directionality and tunability at the nanoscale.

Contribution

It introduces a novel method using DNA origami to precisely position fluorophores near silicon nanoparticles for directional emission control.

Findings

Achieved unidirectional emission with up to ~7 dB forward-to-backward ratio.

Silicon nanospheres can act as color routers or beam steerers.

Demonstrated tunable emission control based on size and spectral range.

Abstract

Single-photon emitters radiate as electric dipoles, which limits light collection efficiency and complicates integration into flat photonic devices. Developing nanophotonic structures capable of directing photon emission with tunable angular distributions in the visible spectrum has been pursued for applications ranging from integrated optical systems to discrimination of molecular species. To date, such directional control has been achieved using components whose overall footprint is larger than the emission wavelength and often rely on lossy plasmonic components. Here, we employ the DNA origami technique for deterministic nanoscale assembly, positioning single fluorophores in nanometric proximity to a single silicon spherical nanoparticle and demonstrate unidirectional emission with forward-to-backward intensity ratios up to ~7 dB. Furthermore, we show that a single silicon nanosphere antenna can function as a color router or a beam steerer depending on its size, emitter spectral range and emitter-nanoparticle distance.