Single Quantum Dot Coupled to a Scanning Optical Antenna: A Tunable Superemitter

Farahani, Javad N.; Pohl, Dieter; Eisler, Hans‐Jürgen; Hecht, Bert

doi:10.1103/physrevlett.95.017402

Cited by 596 publications

(567 citation statements)

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“…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].…”

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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“…[1][2][3][4][5] This versatility results from a dramatic influence that plasmons impose on the absorption and emission properties of nearby located dipoles, for example, semiconductor nanocrystals and nanowires [6][7][8][9][10][11][12] or dye molecules. [13][14][15][16][17][18] Optical response of an emitter coupled to a plasmonic structure depends upon spatial arrangement as well as spectral characteristics of a studied system.…”

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confidence: 99%

Metal-Enhanced Fluorescence of Chlorophylls in Single Light-Harvesting Complexes

et al. 2007

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Ensemble and single-molecule spectroscopy demonstrates that both emission and absorption of peridinin−chlorophyll−protein photosynthetic antennae can be largely enhanced through plasmonic interactions. We find up to 18-fold increase of the chlorophyll fluorescence for complexes placed near a silver metal layer. This enhancement, which leaves no measurable effects on the protein structure, is observed when exciting either chlorophyll or carotenoid and is attributed predominantly to an increase of the excitation rate in the antenna. The enhancement mechanism comes from plasmon-induced amplification of electromagnetic fields inside the complex. This result is an important step toward applying plasmonic nanostructures for controlling the optical response of complex biomolecules and improving the design and functioning of artificial light-harvesting systems.Strong enhancement of electromagnetic fields generated through plasmon resonances in metal films and particles has recently stimulated a considerable interest in diverse research fields such as optical spectroscopy, cell imaging, quantum information processing, nanophotonics, and biosensors. [1][2][3][4][5] This versatility results from a dramatic influence that plasmons impose on the absorption and emission properties of nearby located dipoles, for example, semiconductor nanocrystals and nanowires 6-12 or dye molecules. [13][14][15][16][17][18] Optical response of an emitter coupled to a plasmonic structure depends upon spatial arrangement as well as spectral characteristics of a studied system. Remarkable progress has been made in on-demand design of metal nanostructures, which is essential for tuning the resonance frequency and thus the coupling strength. 13,14,19 Complementary efforts focused on developing advanced experiments to study dipoles placed in the vicinity of a metal nanoparticle have shed light on the interplay between radiative and nonradiative processes in these systems. 16,18 This very relation determines whether the fluorescence is enhanced [9][10][11]16 or quenched due to the dominating role of nonradiative energy transfer from the dipole to the metal. 15,18 Metal-enhanced fluorescence (MEF) has been observed for many hybrid systems that include nanocrystals on corrugated metal surfaces, 10,11 dye molecules coupled to metal nanoparticles, 18 and nanocrystal-nanoparticle bioconjugates. 8 In all these cases, very stable and highly fluorescing emitters have been selected. It would be, however, highly desirable to apply MEF to weakly fluorescing systems such as DNA, 20 carbon nanotubes 21 or, yet experimentally unexplored in this context, light-harvesting complexes. These latter proteinpigment systems, which contain chlorophyll (Chl) and carotenoid molecules embedded in a protein matrix, participate in the photosynthesis process by collecting sunlight energy and transferring it to reactions centers. The presence of fluorescing Chls and the protein, separated by a few nanometers, renders light-harvesting complexes ideal for studying the prot...

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“…After appropriate filtering, the collected light (photoluminescence emission around 585 nm) was detected by a single-photon counting avalanche photodiode (SPAD, SPCM-AQR13, Perkin Elmer) connected to a time- amounts to 170 nm with a feed gap width of 50 nm. This is longer than the estimated half-wave antenna resonance length of 120 nm, assuming an average dielectric constant (glass and Si 3 N 4 ) of the environment, and the first minimum of the antenna responsivity at about twice that length [16]. We present two sets of data recorded in different modes of operation.…”

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confidence: 99%

“…The confocal PL intensity map can be used as a reference, since the laser excitation intensity for this map and all other data had been kept constant at 1.8 µW µm −2 , well below the saturation intensity of the quantum dots [16]. Comparison of a typical PL feature in the confocal PL image, figure 3(c), and the corresponding antenna modified PL feature, figure 3(d), clearly demonstrates two main features: (i) the PL response of the quantum dot interacting with the optical antenna is locally enhanced by a factor of three with respect to the peak of the diffractionlimited confocal spot and (ii) the full-width-at-half-maximum of the locally enhanced PL spot size matches the feed gap width of the optical bow-tie antenna (≈50 nm) as supported by the corresponding line cuts in figure 3(e).…”

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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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Single Quantum Dot Coupled to a Scanning Optical Antenna: A Tunable Superemitter

Cited by 596 publications

References 30 publications

Mode Imaging and Selection in Strongly Coupled Nanoantennas

Mode Imaging and Selection in Strongly Coupled Nanoantennas

Metal-Enhanced Fluorescence of Chlorophylls in Single Light-Harvesting Complexes

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

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