Limits...
Ultrafast spontaneous emission source using plasmonic nanoantennas.

Hoang TB, Akselrod GM, Argyropoulos C, Huang J, Smith DR, Mikkelsen MH - Nat Commun (2015)

Bottom Line: The antennas consist of silver nanocubes coupled to a gold film separated by a thin polymer spacer layer and colloidal core-shell quantum dots, a stable and technologically relevant emitter.We show an increase in the spontaneous emission rate of a factor of 880 and simultaneously a 2,300-fold enhancement in the total fluorescence intensity, which indicates a high radiative quantum efficiency of ∼50%.The nanopatch antenna geometry can be tuned from the visible to the near infrared, providing a promising approach for nanophotonics based on ultrafast spontaneous emission.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Physics, Duke University, Durham, North Carolina 27708, USA. [2] Center for Metamaterials and Integrated Plasmonics, Duke University, Durham, North Carolina 27708, USA.

ABSTRACT
Typical emitters such as molecules, quantum dots and semiconductor quantum wells have slow spontaneous emission with lifetimes of 1-10 ns, creating a mismatch with high-speed nanoscale optoelectronic devices such as light-emitting diodes, single-photon sources and lasers. Here we experimentally demonstrate an ultrafast (<11 ps) yet efficient source of spontaneous emission, corresponding to an emission rate exceeding 90 GHz, using a hybrid structure of single plasmonic nanopatch antennas coupled to colloidal quantum dots. The antennas consist of silver nanocubes coupled to a gold film separated by a thin polymer spacer layer and colloidal core-shell quantum dots, a stable and technologically relevant emitter. We show an increase in the spontaneous emission rate of a factor of 880 and simultaneously a 2,300-fold enhancement in the total fluorescence intensity, which indicates a high radiative quantum efficiency of ∼50%. The nanopatch antenna geometry can be tuned from the visible to the near infrared, providing a promising approach for nanophotonics based on ultrafast spontaneous emission.

No MeSH data available.


Related in: MedlinePlus

Spectral properties of the NPA.(a) Dark field scattering image showing individual NPAs as bright spots with different intensities because of different scattering amplitudes and resonant wavelengths. Scale bar, 5 μm. (b) Fluorescence image of the same location when illuminated by a defocused 514 nm CW laser. Several NPAs, labelled 1, 2 and 3, are visible in the scattering and fluorescence images. Only NPAs resonant with the QD emission are visible in the fluorescence image. Scale bar, 5 μm. (c) Measured and simulated scattering spectrum of a single NPA with a polymer-filled gap and no QDs, in normalized units. (d) Measured scattering spectrum of a single NPA containing QDs in the gap region. The measured fluorescence spectrum for QDs coupled to the NPA is also displayed in red showing good overlap with the scattering spectrum. Exp., experimental; Sim., simulation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4525280&req=5

f2: Spectral properties of the NPA.(a) Dark field scattering image showing individual NPAs as bright spots with different intensities because of different scattering amplitudes and resonant wavelengths. Scale bar, 5 μm. (b) Fluorescence image of the same location when illuminated by a defocused 514 nm CW laser. Several NPAs, labelled 1, 2 and 3, are visible in the scattering and fluorescence images. Only NPAs resonant with the QD emission are visible in the fluorescence image. Scale bar, 5 μm. (c) Measured and simulated scattering spectrum of a single NPA with a polymer-filled gap and no QDs, in normalized units. (d) Measured scattering spectrum of a single NPA containing QDs in the gap region. The measured fluorescence spectrum for QDs coupled to the NPA is also displayed in red showing good overlap with the scattering spectrum. Exp., experimental; Sim., simulation.

Mentions: The NPAs are fabricated via the deposition of a sparse layer of colloidal QDs on top of a ∼1 nm poly(allylamine) hydrochloride (PAH) layer on a gold (Au) film, followed by electrostatic adhesion of colloidally synthesized silver nanocubes. On average, ∼10 QDs are located under each nanocube, as determined by transmission electron microscopy of a similar sample prepared on a carbon film instead of a Au film (Fig. 1c). Using a custom-built microscope, individual NPAs are identified by dark-field and fluorescence imaging (Fig. 2a,b), followed by spectroscopy (Fig. 2c,d) and time-resolved fluorescence measurements on the located nanoparticles (see Methods). Owing to the distribution of nanocube sizes, only a subset of NPAs is resonant with the QD fluorescence, as shown in Fig. 2b.


Ultrafast spontaneous emission source using plasmonic nanoantennas.

Hoang TB, Akselrod GM, Argyropoulos C, Huang J, Smith DR, Mikkelsen MH - Nat Commun (2015)

Spectral properties of the NPA.(a) Dark field scattering image showing individual NPAs as bright spots with different intensities because of different scattering amplitudes and resonant wavelengths. Scale bar, 5 μm. (b) Fluorescence image of the same location when illuminated by a defocused 514 nm CW laser. Several NPAs, labelled 1, 2 and 3, are visible in the scattering and fluorescence images. Only NPAs resonant with the QD emission are visible in the fluorescence image. Scale bar, 5 μm. (c) Measured and simulated scattering spectrum of a single NPA with a polymer-filled gap and no QDs, in normalized units. (d) Measured scattering spectrum of a single NPA containing QDs in the gap region. The measured fluorescence spectrum for QDs coupled to the NPA is also displayed in red showing good overlap with the scattering spectrum. Exp., experimental; Sim., simulation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525280&req=5

f2: Spectral properties of the NPA.(a) Dark field scattering image showing individual NPAs as bright spots with different intensities because of different scattering amplitudes and resonant wavelengths. Scale bar, 5 μm. (b) Fluorescence image of the same location when illuminated by a defocused 514 nm CW laser. Several NPAs, labelled 1, 2 and 3, are visible in the scattering and fluorescence images. Only NPAs resonant with the QD emission are visible in the fluorescence image. Scale bar, 5 μm. (c) Measured and simulated scattering spectrum of a single NPA with a polymer-filled gap and no QDs, in normalized units. (d) Measured scattering spectrum of a single NPA containing QDs in the gap region. The measured fluorescence spectrum for QDs coupled to the NPA is also displayed in red showing good overlap with the scattering spectrum. Exp., experimental; Sim., simulation.
Mentions: The NPAs are fabricated via the deposition of a sparse layer of colloidal QDs on top of a ∼1 nm poly(allylamine) hydrochloride (PAH) layer on a gold (Au) film, followed by electrostatic adhesion of colloidally synthesized silver nanocubes. On average, ∼10 QDs are located under each nanocube, as determined by transmission electron microscopy of a similar sample prepared on a carbon film instead of a Au film (Fig. 1c). Using a custom-built microscope, individual NPAs are identified by dark-field and fluorescence imaging (Fig. 2a,b), followed by spectroscopy (Fig. 2c,d) and time-resolved fluorescence measurements on the located nanoparticles (see Methods). Owing to the distribution of nanocube sizes, only a subset of NPAs is resonant with the QD fluorescence, as shown in Fig. 2b.

Bottom Line: The antennas consist of silver nanocubes coupled to a gold film separated by a thin polymer spacer layer and colloidal core-shell quantum dots, a stable and technologically relevant emitter.We show an increase in the spontaneous emission rate of a factor of 880 and simultaneously a 2,300-fold enhancement in the total fluorescence intensity, which indicates a high radiative quantum efficiency of ∼50%.The nanopatch antenna geometry can be tuned from the visible to the near infrared, providing a promising approach for nanophotonics based on ultrafast spontaneous emission.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Physics, Duke University, Durham, North Carolina 27708, USA. [2] Center for Metamaterials and Integrated Plasmonics, Duke University, Durham, North Carolina 27708, USA.

ABSTRACT
Typical emitters such as molecules, quantum dots and semiconductor quantum wells have slow spontaneous emission with lifetimes of 1-10 ns, creating a mismatch with high-speed nanoscale optoelectronic devices such as light-emitting diodes, single-photon sources and lasers. Here we experimentally demonstrate an ultrafast (<11 ps) yet efficient source of spontaneous emission, corresponding to an emission rate exceeding 90 GHz, using a hybrid structure of single plasmonic nanopatch antennas coupled to colloidal quantum dots. The antennas consist of silver nanocubes coupled to a gold film separated by a thin polymer spacer layer and colloidal core-shell quantum dots, a stable and technologically relevant emitter. We show an increase in the spontaneous emission rate of a factor of 880 and simultaneously a 2,300-fold enhancement in the total fluorescence intensity, which indicates a high radiative quantum efficiency of ∼50%. The nanopatch antenna geometry can be tuned from the visible to the near infrared, providing a promising approach for nanophotonics based on ultrafast spontaneous emission.

No MeSH data available.


Related in: MedlinePlus