Improving the Mismatch between Light and Nanoscale Objects with Gold Bowtie Nanoantennas

Schuck, P. James; Fromm, David P.; Sundaramurthy, Arvind; Kino, G. S.; Moerner, W. E.

doi:10.1103/physrevlett.94.017402

Cited by 968 publications

(907 citation statements)

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“…Nanoantennas consisting of two strongly coupled particles can serve as a model system to study the impact of mode selectivity [6,8,9]. Upon illumination nanoantennas confine and enhance optical fields [10,11] and can therefore be used to tailor the interaction of light with nanomatter [12]. Various applications of nanoantennas have been proposed and experimentally demonstrated, including enhanced single-emitter fluorescence [13][14][15], enhanced Raman scattering [16,17], near-field polarization engineering [18][19][20], high-harmonic generation [21,22], as well as applications in integrated optical nanocircuitry [23,24].…”

Section: Introductionmentioning

confidence: 99%

Mode Imaging and Selection in Strongly Coupled Nanoantennas

et al. 2010

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The number of eigenmodes in plasmonic nanostructures increases with complexity due to mode hybridization, raising the need for efficient mode characterization and selection. Here we experimentally demonstrate direct imaging and selective excitation of the "bonding" and "antibonding" plasmon mode in symmetric dipole nanoantennas using confocal two-photon photoluminescence mapping. Excitation of a high-qualityfactor antibonding resonance manifests itself as a two-lobed pattern instead of the single spot observed for the broad "bonding" resonance, in accordance with numerical simulations. The two-lobed pattern is observed due to the fact that excitation of the antibonding mode is forbidden for symmetric excitation at the feedgap, while concomitantly the mode energy splitting is large enough to suppress excitation of the "bonding" mode. The controlled excitation of modes in strongly coupled plasmonic nanostructures is mandatory for efficient sensors, in coherent control as well as for implementing well-defined functionalities in complex plasmonic devices. IntroductionPlasmonic nanostructures consisting of particular arrangements of closely spaced resonant particles are of great interest since they offer a variety of eigenmodes that evolve due to mode hybridization [1]. Characterization and well-defined excitation of such eigenmodes is important in order to achieve welldefined functionality in devices [2,3] and to successfully apply techniques of coherent control [4][5][6][7]. Nanoantennas consisting of two strongly coupled particles can serve as a model system to study the impact of mode selectivity [6,8,9]. Upon illumination nanoantennas confine and enhance optical fields [10,11] and can therefore be used to tailor the interaction of light with nanomatter [12]. Various applications of nanoantennas have been proposed and experimentally demonstrated, including enhanced single-emitter fluorescence [13][14][15], enhanced Raman scattering [16,17], near-field polarization engineering [18][19][20], high-harmonic generation [21,22], as well as applications in integrated optical nanocircuitry [23,24]. The longitudinal resonances of a symmetric dipole antenna can be understood in terms of hybridization of the longitudinal resonances of individual antenna arms, caused by the coupling over the narrow feedgap [25,26]. Such coupling causes a mode splitting into a lower-energy "bonding" mode and a higher-energy "antibonding" mode, respectively (Fig. 1). Limited by the uncertainty of conventional nanofabrication, it is often difficult to fabricate antenna arrays with a reproducible gap size below 20 nm, which is necessary to achieve significant energy splitting between the bonding and the antibonding mode. As a result, the existence of the antibonding antenna resonance has hardly been considered, although it may offer interesting opportunities, such as impedance tunability, a high quality factor due to its weakly radiative nature, the launching of propagating plasmon modes with increased propagation lengths [27] and spatial select...

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Section: Introductionmentioning

confidence: 99%

Mode Imaging and Selection in Strongly Coupled Nanoantennas

et al. 2010

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“…Note that in our structures, due to the narrow gap, the effective index n eff can be as high as 14. The resulting strong localization of the optical near-field in all three dimensions leads to unprecedentedly small modal volumes 30 of 463 nm 3 for the 2 nd -order cavity mode.…”

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Atomic-Scale Confinement of Resonant Optical Fields

Kern¹,

Großmann²,

Tarakina³

et al. 2012

Nano Lett.

138

157

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2The interaction of light and matter, i.e. absorption and emission of photons, can be considerably enhanced in the presence of strongly localized and therefore highly intense optical near fields 1 .Plasmonic antennas consisting of pairs of closely spaced metal nano particles have gained much attention in this context since they provide the possibility to strongly concentrate optical fields into the gap between the two metal particles [2][3][4] . Pairs of closely spaced metal nanoparticles supporting plasmonic gap resonances consequently find broad applications, e.g. in single-emitter surfaceenhanced spectroscopy 5,6 , quantum optics 7 , extreme nonlinear optics 8-10 , optical trapping 11 , metamaterials 12, 13 and molecular opto-electronics 14 .The success of metal-insulator-metal structures is based on two fundamental properties of their anti-symmetric electromagnetic gap modes. (i) As a direct consequence of the boundary conditions, the dominating field components normal to the metal-dielectric interfaces are sizable only inside the dielectric gap. This means that for anti-symmetric gap modes the achievable field confinement is not limited by the skin depth of the metal, but is solely determined by the actual size of the gap. (ii) Since the free electrons of the metal respond resonantly to an external optical frequency field, enormous surface charge accumulations, accompanied by ultra-intense optical near fields, will occur. In addition, with decreasing gap width, stronger attractive coulomb forces 4 across the gap lead to further surface-charge accumulation and a concomitantly increased near-field intensity enhancement. We therefore conclude that an experimental realization of atomic-scale concentration of electromagnetic fields at visible frequencies is possible but it requires atomic-scale shape control of the field-confining structure, i.e. the gap, as well as a careful assignment and selection of suitable optical modes.Here we achieve atomic-scale confinement of electromagnetic fields at visible frequencies by combining for the first time both atomic-scale shape control of the field confining structure 15 as well as a careful selection and assignment of suitable optical modes [16][17][18] . We study single-crystalline nanorods which self-assemble into side-by-side aligned dimers with gap widths below 0.5 nm. Sideby-side aligned nanorod dimers possess various distinguishable symmetric and anti-symmetric 3 modes in the visible range 19 . In contrast to previous work 20-22 we demonstrate full control over symmetric and anti-symmetric optical modes by means of white-light scattering experiments. We experimentally demonstrate the presence of atomic-scale light confinement in these structures by observing an extreme > 800 meV hybridization splitting of corresponding symmetric and antisymmetric dimer modes. Our results open new perspectives for atomically-resolved spectroscopic imaging, deeply nonlinear optics and attosecond physics, cavity optomechanics and ultra-sensing as well as quantum optics.To obtain nano...

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“…We demonstrate that, even in this complex geometry, it is possible to control key antenna parameters such as overall length and width of the feed gap by focused-ion-beam milling. Merging well-established scanning probe technology with the concept of resonant optical antennas [13,14] leads to a powerful new method of scanning optical microscopy in which an engineered optical hot spot is used as an optical probe [15]. We demonstrate the application of scanning optical antennas to the imaging of single quantum dots at room temperature.…”

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confidence: 99%

Bow-tie optical antenna probes for single-emitter scanning near-field optical microscopy

et al. 2007

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A method for the fabrication of bow-tie optical antennas at the apex of pyramidal Si 3 N 4 atomic force microscopy tips is described. We demonstrate that these novel optical probes are capable of sub-wavelength imaging of single quantum dots at room temperature. The enhanced and confined optical near-field at the antenna feed gap leads to locally enhanced photoluminescence (PL) of single quantum dots. Photoluminescence quenching due to the proximity of metal is found to be insignificant. The method holds promise for single quantum emitter imaging and spectroscopy at spatial resolution limited by the engineered antenna gap width exclusively.High-precision engineering of prototype devices that show function through their design and high complexity is a key target of applied nanoscale science and nanotechnology. Resonant optical antennas in the field of nano-photonics, with their architecture stimulated by their radio frequency counterparts, synergistically combine (i) electromagnetic field confinement and enhancement defined by the size of their feed gap width and (ii) impedance matching of optical waves mediated by the effective length of their antenna arms [1]. The control of sub-wavelength confined and enhanced optical fields pushes the limit in optical characterization [2][3][4] manipulation [5][6][7], and optimization of single nanoscale light sources for information processing [8][9][10][11] on the nanometre scale. In particular, the impedance matching of optical waves opens an efficient pathway to transfer near-field information into the optical far-field, and vice versa [12].In this paper, we present a strategy for designing bow-tie optical antennas at the apex of Si 3 N 4 atomic force microscopy (AFM) cantilever tips. We demonstrate that, even in this complex geometry, it is possible to control key antenna parameters such as overall length and width of the feed gap by focused-ion-beam milling. Merging well-established scanning probe technology with the concept of resonant optical antennas [13,14] leads to a powerful new method of scanning optical microscopy in which an engineered optical hot spot is used as an optical probe [15]. We demonstrate the application of scanning optical antennas to the imaging of single quantum dots at room temperature. We show that the emission of individual quantum dots is enhanced when scanned across the antenna feed gap while concomitantly their excited-state lifetime is reduced. The field confinement, characterized by

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Improving the Mismatch between Light and Nanoscale Objects with Gold Bowtie Nanoantennas

Cited by 968 publications

References 21 publications

Mode Imaging and Selection in Strongly Coupled Nanoantennas

Mode Imaging and Selection in Strongly Coupled Nanoantennas

Atomic-Scale Confinement of Resonant Optical Fields

Bow-tie optical antenna probes for single-emitter scanning near-field optical microscopy

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