Cavity resonances of metal-dielectric-metal nanoantennas

Joshi, Bhuwan; Wei, Qi‐Huo

doi:10.1364/oe.16.010315

Cited by 18 publications

(17 citation statements)

References 7 publications

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“…The behavior predicted for the latter is similar to that for spherical particles, with a set of bonding modes that strongly red-shift with narrowing gaps and that determine both the near-and the far-field response. 17 In contrast, for the corresponding flat-gap antennas, we found two different sets of modes, 20,21,84 longitudinal antenna plasmons and transverse cavity plasmons, which behave in fundamentally different ways. The LAPs dominate the far-field response and saturate spectrally for narrow gaps.…”

Section: ■ Summary and Discussionmentioning

confidence: 64%

The Morphology of Narrow Gaps Modifies the Plasmonic Response

et al. 2015

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ABSTRACT:The optical response of a plasmonic gapantenna is mainly determined by the Coulomb interaction of the two constituent arms of the antenna. Using rigorous calculations supported by simple analytical models, we observe how the morphology of a nanometric gap separating two metallic rods dramatically modifies the plasmonic response. In the case of rounded terminations at the gap, a conventional set of bonding modes is found that red-shifts strongly with decreasing separation. However, in the case of flat surfaces, a distinctly different situation is found with the appearance of two sets of modes: (i) strongly radiating longitudinal antenna plasmons (LAPs), which exhibit a red-shift that saturates for very narrow gaps, and (ii) transverse cavity plasmons (TCPs) confined to the gap, which are weakly radiative and strongly dependent on the separation distance between the two arms. The two sets of modes can be independently tuned, providing detailed control of both the near-and far-field response of the antenna. We illustrate these properties also with an application to larger infrared gap-antennas made of polar materials such as SiC. Finally we use the quantum corrected model (QCM) to show that the morphology of the gap has a dramatic influence on the plasmonic response also for subnanometer gaps. This effect can be crucial for the correct interpretation of charge transfer processes in metallic cavities where quantum effects such as electron tunneling are important. KEYWORDS: optical antennas, plasmonic gaps, cavity modes, antenna modes, quantum effects, quantum corrected model, plasmonic resonances, phononic resonances M etallic particles can show a strong optical response due to the excitation of resonant plasmonic modes, making light manipulation possible in structures of dimensions comparable to or smaller than the wavelength. Typical effects are the efficient emission of radiation and the concentration of the incoming light energy in small volumes, thus justifying the characterization of these metallic structures as optical antennas. 1,2 Modifications of the geometry, size, or materials 3−6 affect the optical response. In particular, the resonant modes of optical antennas consisting of two metallic particles separated by a narrow gap show significant sensitivity to the properties of the gap. 7−19 In an optical antenna, a change in geometry can simultaneously affect both the strength and wavelength of its resonances and modify both the far-and near-field response. It is usually a challenge, for example, to control the near field without affecting the far-field properties. In this theoretical work, we discuss how the coexistence 20,21 of two different and mostly spectrally decoupled types of modes in flat-gap antennas, namely, transverse cavity modes 22 and longitudinal antenna modes, 15 allows for a more flexible tuning of far-and near-field properties compared to that of the conventional spherical-gap terminations 13,17,23 The importance of the gap morphology 24 is particularly pronounced for nanometer-...

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Section: ■ Summary and Discussionmentioning

confidence: 64%

The Morphology of Narrow Gaps Modifies the Plasmonic Response

et al. 2015

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“…Numerous studies have demonstrated that well-designed metallic nanostructures exhibit excellent performances as optical nanoantennae, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] plasmonic nanocavities, and sub-wavelength waveguides. [19][20][21][22][23] Metal nanoparticles, [1][2][3] monopole and dipole metal nanorods, [4,5] multipole metal nanocrescents and nanorings: [6][7][8] all of these examples have strong surface plasmon resonance and could be employed as optical nanoantennae to efficiently interconvert the propagating radiation and confined local fields, which have been applied in surface-enhanced raman scattering (SERS), [24][25][26] sensing, and nanospectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Illuminating Dark Plasmons of Silver Nanoantenna Rings to Enhance Exciton–Plasmon Interactions

Gong

Zhou

et al. 2009

Adv Funct Materials

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The chemical growth of silver nanorings that possess singly twinned crystals and a circular cross section via a reductive reaction solution is reported. The wire and ring diameters of the synthesized nanorings are in the ranges 80–200 nm and 4.5–18.0 μm, respectively. By lighting up the multipolar dark plasmons with slanted illumination, the silver nanoring exhibits unique focused scattering and large local‐field enhancement. We also demonstrate strong exciton–plasmon interactions between a monolayer of CdSe/ZnS semiconductor quantum dots and a single silver antenna‐like nanoring (nanoantenna) at the “hot spots” located at the cross points of the incident plane and nanoring; the position of these spots are tunable by adjusting the incidence angle of illumination. The tunable plasmonic behavior of the silver nanorings could find applications as optical nanoantennae or plasmonic nanocavities.

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“…These ideas have guided the efficient design of metasurfaces 6,7 and the modelling of a variety of composite nanostructures, including plasmonic NP clusters [8][9][10] , NP rings exhibiting strong optical magnetism 11 and microcavity lasers 12 . However, the direct application of these concepts to photonic circuits has so far been limited to modelling and tuning optical nanoantennas [13][14][15][16][17][18][19] , and to realizing a ladder network of two-dimensional (2D) nanoinductors and nanocapacitors in the form of a subwavelength grating at mid-infrared frequencies 4 . These earlier experiments have demonstrated nanocircuits with limited complexity and specific symmetry constraints.…”

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confidence: 99%

Modular assembly of optical nanocircuits

et al. 2014

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A key element enabling the microelectronic technology advances of the past decades has been the conceptualization of complex circuits with versatile functionalities as being composed of the proper combination of basic 'lumped' circuit elements (for example, inductors and capacitors). In contrast, modern nanophotonic systems are still far from a similar level of sophistication, partially because of the lack of modularization of their response in terms of basic building blocks. Here we demonstrate the design, assembly and characterization of relatively complex photonic nanocircuits by accurately positioning a number of metallic and dielectric nanoparticles acting as modular lumped elements. The nanoparticle clusters produce the desired spectral response described by simple circuit rules and are shown to be dynamically reconfigurable by modifying the direction or polarization of impinging signals. Our work represents an important step towards extending the powerful modular design tools of electronic circuits into nanophotonic systems.

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Cavity resonances of metal-dielectric-metal nanoantennas

Cited by 18 publications

References 7 publications

The Morphology of Narrow Gaps Modifies the Plasmonic Response

The Morphology of Narrow Gaps Modifies the Plasmonic Response

Illuminating Dark Plasmons of Silver Nanoantenna Rings to Enhance Exciton–Plasmon Interactions

Modular assembly of optical nanocircuits

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