Limits...
Wedge Waveguides and Resonators for Quantum Plasmonics.

Kress SJ, Antolinez FV, Richner P, Jayanti SV, Kim DK, Prins F, Riedinger A, Fischer MP, Meyer S, McPeak KM, Poulikakos D, Norris DJ - Nano Lett. (2015)

Bottom Line: However, because these localized modes are also dissipative, structures that offer the best compromise between field confinement and loss have been sought.As our structures offer modal volumes down to ~0.004λvac(3) in an exposed single-mode waveguide-resonator geometry, they provide advantages over both traditional photonic microcavities and localized-plasmonic resonators for enhancing light-matter interactions.Our results confirm the promise of wedges for creating plasmonic devices and for studying coherent quantum-plasmonic effects such as long-distance plasmon-mediated entanglement and strong plasmon-matter coupling.

View Article: PubMed Central - PubMed

Affiliation: Optical Materials Engineering Laboratory, ETH Zurich , 8092 Zurich, Switzerland.

ABSTRACT
Plasmonic structures can provide deep-subwavelength electromagnetic fields that are useful for enhancing light-matter interactions. However, because these localized modes are also dissipative, structures that offer the best compromise between field confinement and loss have been sought. Metallic wedge waveguides were initially identified as an ideal candidate but have been largely abandoned because to date their experimental performance has been limited. We combine state-of-the-art metallic wedges with integrated reflectors and precisely placed colloidal quantum dots (down to the single-emitter level) and demonstrate quantum-plasmonic waveguides and resonators with performance approaching theoretical limits. By exploiting a nearly 10-fold improvement in wedge-plasmon propagation (19 μm at a vacuum wavelength, λvac, of 630 nm), efficient reflectors (93%), and effective coupling (estimated to be >70%) to highly emissive (~90%) quantum dots, we obtain Ag plasmonic resonators at visible wavelengths with quality factors approaching 200 (3.3 nm line widths). As our structures offer modal volumes down to ~0.004λvac(3) in an exposed single-mode waveguide-resonator geometry, they provide advantages over both traditional photonic microcavities and localized-plasmonic resonators for enhancing light-matter interactions. Our results confirm the promise of wedges for creating plasmonic devices and for studying coherent quantum-plasmonic effects such as long-distance plasmon-mediated entanglement and strong plasmon-matter coupling.

No MeSH data available.


Related in: MedlinePlus

Characterization of single-mode, deep-subdiffraction wedge-plasmonpolaritons (WPPs). (a–c) False-color fluorescence micrographsof QDs (bright spots, emission peak at 630 nm) placed on the apexes(dashed vertical lines in the image centers) of Ag wedges at differentdistances from bump lines. WPPs are launched by the QDs and scatterlight (squares) at the bumps (scale bar = 5 μm). (d–f)Magnified views of the scattered light from the bump lines in (a–c),normalized for comparison (scale bar = 500 nm). (g–i) Spatialcross sections of the scattered signals in (d–f) in the x direction (blue) and the y direction(red) compared with the expected signal of an ideal point dipole (blackline). (j, k) False-color fluorescence micrographs from Ag wedgeswith QDs emitting at 630 and 564 nm, respectively. The bright spotsin the center are direct fluorescence. With long exposure times, weakscattered light from WPPs propagating along the wedge apexes is detectedas horizontal streaks on either side (scale bar = 10 μm). Thehorizontal dashed lines show the bases of the wedges. (l) Intensityprofiles plotted along the wedge between the vertical lines in (j,k), yielding propagation lengths of 19.0 and 15.4 μm for WPPsgenerated by red and green QDs, respectively. (m) Fluorescence spectraof the red and green QDs.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4566130&req=5

fig3: Characterization of single-mode, deep-subdiffraction wedge-plasmonpolaritons (WPPs). (a–c) False-color fluorescence micrographsof QDs (bright spots, emission peak at 630 nm) placed on the apexes(dashed vertical lines in the image centers) of Ag wedges at differentdistances from bump lines. WPPs are launched by the QDs and scatterlight (squares) at the bumps (scale bar = 5 μm). (d–f)Magnified views of the scattered light from the bump lines in (a–c),normalized for comparison (scale bar = 500 nm). (g–i) Spatialcross sections of the scattered signals in (d–f) in the x direction (blue) and the y direction(red) compared with the expected signal of an ideal point dipole (blackline). (j, k) False-color fluorescence micrographs from Ag wedgeswith QDs emitting at 630 and 564 nm, respectively. The bright spotsin the center are direct fluorescence. With long exposure times, weakscattered light from WPPs propagating along the wedge apexes is detectedas horizontal streaks on either side (scale bar = 10 μm). Thehorizontal dashed lines show the bases of the wedges. (l) Intensityprofiles plotted along the wedge between the vertical lines in (j,k), yielding propagation lengths of 19.0 and 15.4 μm for WPPsgenerated by red and green QDs, respectively. (m) Fluorescence spectraof the red and green QDs.

Mentions: Figure 3 characterizes the plasmonic properties of our Ag wedges.QDs with an emission maximum at 630 nm were printed onto waveguidesthat included bump lines at three distances (Figure 3a–c). Upon photoexcitation of theQDs (bright spots in Figure 3a–c), WPPs are launched along the wedge and scatterinto photons at the bump lines (squares in Figure 3a–c). These scattering signals decaywith increasing distance from the QDs, indicative of propagating WPPs.When the intensities of these signals are normalized (Figure 3d–f), their spatialextents are identical within measurement error. This is confirmedby the cross sections (Figure 3g–i) in the x direction (blue) andthe y direction (red). Further, these scatteringsignals are within 10% of that for an ideal point dipole emittingat 630 nm (approximated by a Gaussian). Similar results are shownfor Au wedges in Figure S7. Because thebump lines are extended along the wedge faces, the lack of scatteringon the faces confirms that near-field dipolar sources (such as QDs)can excite subdiffraction WPPs that propagate only along the apex,as expected from Figure 2.


Wedge Waveguides and Resonators for Quantum Plasmonics.

Kress SJ, Antolinez FV, Richner P, Jayanti SV, Kim DK, Prins F, Riedinger A, Fischer MP, Meyer S, McPeak KM, Poulikakos D, Norris DJ - Nano Lett. (2015)

Characterization of single-mode, deep-subdiffraction wedge-plasmonpolaritons (WPPs). (a–c) False-color fluorescence micrographsof QDs (bright spots, emission peak at 630 nm) placed on the apexes(dashed vertical lines in the image centers) of Ag wedges at differentdistances from bump lines. WPPs are launched by the QDs and scatterlight (squares) at the bumps (scale bar = 5 μm). (d–f)Magnified views of the scattered light from the bump lines in (a–c),normalized for comparison (scale bar = 500 nm). (g–i) Spatialcross sections of the scattered signals in (d–f) in the x direction (blue) and the y direction(red) compared with the expected signal of an ideal point dipole (blackline). (j, k) False-color fluorescence micrographs from Ag wedgeswith QDs emitting at 630 and 564 nm, respectively. The bright spotsin the center are direct fluorescence. With long exposure times, weakscattered light from WPPs propagating along the wedge apexes is detectedas horizontal streaks on either side (scale bar = 10 μm). Thehorizontal dashed lines show the bases of the wedges. (l) Intensityprofiles plotted along the wedge between the vertical lines in (j,k), yielding propagation lengths of 19.0 and 15.4 μm for WPPsgenerated by red and green QDs, respectively. (m) Fluorescence spectraof the red and green QDs.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4566130&req=5

fig3: Characterization of single-mode, deep-subdiffraction wedge-plasmonpolaritons (WPPs). (a–c) False-color fluorescence micrographsof QDs (bright spots, emission peak at 630 nm) placed on the apexes(dashed vertical lines in the image centers) of Ag wedges at differentdistances from bump lines. WPPs are launched by the QDs and scatterlight (squares) at the bumps (scale bar = 5 μm). (d–f)Magnified views of the scattered light from the bump lines in (a–c),normalized for comparison (scale bar = 500 nm). (g–i) Spatialcross sections of the scattered signals in (d–f) in the x direction (blue) and the y direction(red) compared with the expected signal of an ideal point dipole (blackline). (j, k) False-color fluorescence micrographs from Ag wedgeswith QDs emitting at 630 and 564 nm, respectively. The bright spotsin the center are direct fluorescence. With long exposure times, weakscattered light from WPPs propagating along the wedge apexes is detectedas horizontal streaks on either side (scale bar = 10 μm). Thehorizontal dashed lines show the bases of the wedges. (l) Intensityprofiles plotted along the wedge between the vertical lines in (j,k), yielding propagation lengths of 19.0 and 15.4 μm for WPPsgenerated by red and green QDs, respectively. (m) Fluorescence spectraof the red and green QDs.
Mentions: Figure 3 characterizes the plasmonic properties of our Ag wedges.QDs with an emission maximum at 630 nm were printed onto waveguidesthat included bump lines at three distances (Figure 3a–c). Upon photoexcitation of theQDs (bright spots in Figure 3a–c), WPPs are launched along the wedge and scatterinto photons at the bump lines (squares in Figure 3a–c). These scattering signals decaywith increasing distance from the QDs, indicative of propagating WPPs.When the intensities of these signals are normalized (Figure 3d–f), their spatialextents are identical within measurement error. This is confirmedby the cross sections (Figure 3g–i) in the x direction (blue) andthe y direction (red). Further, these scatteringsignals are within 10% of that for an ideal point dipole emittingat 630 nm (approximated by a Gaussian). Similar results are shownfor Au wedges in Figure S7. Because thebump lines are extended along the wedge faces, the lack of scatteringon the faces confirms that near-field dipolar sources (such as QDs)can excite subdiffraction WPPs that propagate only along the apex,as expected from Figure 2.

Bottom Line: However, because these localized modes are also dissipative, structures that offer the best compromise between field confinement and loss have been sought.As our structures offer modal volumes down to ~0.004λvac(3) in an exposed single-mode waveguide-resonator geometry, they provide advantages over both traditional photonic microcavities and localized-plasmonic resonators for enhancing light-matter interactions.Our results confirm the promise of wedges for creating plasmonic devices and for studying coherent quantum-plasmonic effects such as long-distance plasmon-mediated entanglement and strong plasmon-matter coupling.

View Article: PubMed Central - PubMed

Affiliation: Optical Materials Engineering Laboratory, ETH Zurich , 8092 Zurich, Switzerland.

ABSTRACT
Plasmonic structures can provide deep-subwavelength electromagnetic fields that are useful for enhancing light-matter interactions. However, because these localized modes are also dissipative, structures that offer the best compromise between field confinement and loss have been sought. Metallic wedge waveguides were initially identified as an ideal candidate but have been largely abandoned because to date their experimental performance has been limited. We combine state-of-the-art metallic wedges with integrated reflectors and precisely placed colloidal quantum dots (down to the single-emitter level) and demonstrate quantum-plasmonic waveguides and resonators with performance approaching theoretical limits. By exploiting a nearly 10-fold improvement in wedge-plasmon propagation (19 μm at a vacuum wavelength, λvac, of 630 nm), efficient reflectors (93%), and effective coupling (estimated to be >70%) to highly emissive (~90%) quantum dots, we obtain Ag plasmonic resonators at visible wavelengths with quality factors approaching 200 (3.3 nm line widths). As our structures offer modal volumes down to ~0.004λvac(3) in an exposed single-mode waveguide-resonator geometry, they provide advantages over both traditional photonic microcavities and localized-plasmonic resonators for enhancing light-matter interactions. Our results confirm the promise of wedges for creating plasmonic devices and for studying coherent quantum-plasmonic effects such as long-distance plasmon-mediated entanglement and strong plasmon-matter coupling.

No MeSH data available.


Related in: MedlinePlus