Strong coupling and induced transparency at room temperature with single quantum dots and gap plasmons

Haixu Leng,Matthew Pelton,Brian Szychowski,Marie-Christine Daniel

doi:10.1038/s41467-018-06450-4

Haixu Leng, Matthew Pelton + Show 2 more

Open Access

https://doi.org/10.1038/s41467-018-06450-4

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Journal: Nature Communications	Publication Date: Oct 1, 2018
Citations: 186	License type: open-access

Affiliation: University of Maryland, Baltimore County

Abstract

Coherent coupling between plasmons and transition dipole moments in emitters can lead to two distinct spectral effects: vacuum Rabi splitting at strong coupling strengths, and induced transparency (also known as Fano interference) at intermediate coupling strengths. Achieving either strong or intermediate coupling between a single emitter and a localized plasmon resonance has the potential to enable single-photon nonlinearities and other extreme light–matter interactions, at room temperature and on the nanometer scale. Both effects produce two peaks in the spectrum of scattering from the plasmon resonance, and can thus be confused if scattering measurements alone are performed. Here we report measurements of scattering and photoluminescence from individual coupled plasmon–emitter systems that consist of a single colloidal quantum dot in the gap between a gold nanoparticle and a silver film. The measurements unambiguously demonstrate weak coupling (the Purcell effect), intermediate coupling (Fano interference), and strong coupling (Rabi splitting) at room temperature.

Highlights

Coherent coupling between plasmons and transition dipole moments in emitters can lead to two distinct spectral effects: vacuum Rabi splitting at strong coupling strengths, and induced transparency at intermediate coupling strengths
Two peaks were observed in the scattering spectra of plasmonic metal nanostructures coupled to single molecules[14] and single QDs24, and this was taken as evidence of strong coupling
We report straightforward and unambiguous observations of both the strong-coupling regime (Rabi splitting) and the intermediate-coupling regime (Fano interference) for single quantum dots (QDs) coupled to individual metal nanostructures, by measuring scattering and PL from the same structures

Summary

Introduction

Coherent coupling between plasmons and transition dipole moments in emitters can lead to two distinct spectral effects: vacuum Rabi splitting at strong coupling strengths, and induced transparency ( known as Fano interference) at intermediate coupling strengths. Achieving either strong or intermediate coupling between a single emitter and a localized plasmon resonance has the potential to enable single-photon nonlinearities and other extreme light–matter interactions, at room temperature and on the nanometer scale Both effects produce two peaks in the spectrum of scattering from the plasmon resonance, and can be confused if scattering measurements alone are performed. Coupling optical emitters to plasmon resonances in metal nanostructures has long been investigated as a means of increasing their spontaneous emission rates[1] This occurs for weak coupling between the emitter and plasmon; for sufficiently strong coupling, the system is expected to undergo Rabi splitting into new, hybrid modes[2]. There has been only one report of PL splitting for a single emitter (a QD) coupled to a plasmonic metal nanostructure, but the PL spectrum showed an unexpected four-peak structure[29]

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