Optical properties of coupled metallic nanorods for field-enhanced spectroscopy

Aizpurua, Javier; Bryant, Garnett W.; Richter, Lee J.; Abajo, F. Javier García de; Kelley, Brian K.

doi:10.1103/physrevb.71.235420

Cited by 569 publications

(589 citation statements)

References 49 publications

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“…[25][26][27] Here, we present a combined experimental and theoretical study to address the optical response of individual asymmetric dimers both in the linear and nonlinear regime. Comparison of experimental and calculated spectra confirm the interference and coupling of higher-order plasmonic modes in the nanorods, [28][29][30][31][32] providing evidence of the existence of two types of coupling depending on the radiative nature of the modes.…”

mentioning

confidence: 78%

Interference, Coupling, and Nonlinear Control of High-Order Modes in Single Asymmetric Nanoantennas

Abb

Wang²,

Albella

et al. 2012

ACS Nano

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We investigate theoretically and experimentally the structure of plasmonic modes in individual asymmetric dimer antennas. Plasmonic near-field coupling of high-order modes results in hybridization of bright and dark modes of the individual nanorods leading to an anticrossing of the coupled resonances. For two bright modes, hybridization results in a capacitive redshift and superradiant broadening. We show that the properties of asymmetric dimers can be used for nonlinear control of spectral modes and demonstrate such a nonlinear effect by measuring the modulation of a hybrid asymmetric dimer -ITO antenna. With use of full electrodynamical calculations we find that the properties of the near-field nonlinear responses are distinctly different from the far field, which opens up new routes for nonlinear control of plasmonic nanosystems.

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mentioning

confidence: 78%

Interference, Coupling, and Nonlinear Control of High-Order Modes in Single Asymmetric Nanoantennas

Abb

Wang²,

Albella

et al. 2012

ACS Nano

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“…The tapered nanorod array with a magnification mechanism for far-field imaging still suffers critical challenges in achieving accurate growth at tapered angles and introducing gaps between the arrays 47 . With increased efforts towards the development of growth technologies [48][49][50] , experimental demonstrations of the proposed scheme for subwavelength colour imaging could become a reality in the near future.…”

Section: Experimental Hyperlens Demonstration and Recent Advancesmentioning

confidence: 99%

Hyperlenses and metalenses for far-field super-resolution imaging

2012

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The resolution of conventional optical lens systems is always hampered by the diffraction limit. Recent developments in artificial metamaterials provide new avenues to build hyperlenses and metalenses that are able to image beyond the diffraction limit. Hyperlenses project super-resolution information to the far field through a magnification mechanism, whereas metalenses not only super-resolve subwavelength details but also enable optical Fourier transforms. Recently, there have been numerous designs for hyperlenses and metalenses, bringing fresh theoretical and experimental advances, though future directions and challenges remain to be overcome.O ptical microscopy has revolutionized many fields such as microelectronics, biology and medicine. However, the resolution of a conventional optical lens system is always limited by diffraction to about half the wavelength of light. This diffraction barrier arises from the fact that subwavelength information from an object is carried by high spatial-frequency evanescent waves, which only exist in the near field. To overcome this diffraction limit, pioneering work has been carried out, including near-field scanning microscopy 1 , as well as fluorescence-based imaging methods 2,3 . These scanning-or random sampling-based nonprojection techniques achieve super-resolving power by sacrificing imaging speed, making them uncompetitive for dynamic imaging.Lens-based projection imaging remains the best option for high-speed microscopy. Immersion techniques have been proposed to enhance resolution, but they are limited by the low refractive indices of natural materials 4 . Emerging within the last decade, the fields of plasmonics and metamaterials provide solutions for engineering extraordinary material properties not found in nature, such as negative index of refraction 5,6 or strongly anisotropic materials 7,8 . This has provided tremendous opportunities for novel lens designs with unprecedented resolution 9 . Initiated by Pendry's seminal concept of the perfect lens 10 , a number of superlenses were demonstrated with resolving powers beyond the diffraction limit [11][12][13][14][15][16][17] . The optical superlens first achieved sub-diffraction-limited resolution by enhancing evanescent waves through a slab of silver 11 . As the evanescent-field enhancement is enabled by surface plasmon excitation, the subwavelength image is typically limited to the near field of the metal slab. However, the hyperlens-a metamaterial-based lens-can send super-resolution images into the far field by introducing a magnification mechanism. This has been considered as one of the most promising candidates for practical applications since its first demonstration in 2007 (refs 13,14). Recently, various other metamaterial-based lenses, that is, metalenses, have also been developed with both

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“…As sketched in Fig. 1, the energy splitting of the modes in a linear dipole antenna increases with reduced feedgap size, revealing the distance dependent interparticle coupling [8,[28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 95%

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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Optical properties of coupled metallic nanorods for field-enhanced spectroscopy

Cited by 569 publications

References 49 publications

Interference, Coupling, and Nonlinear Control of High-Order Modes in Single Asymmetric Nanoantennas

Interference, Coupling, and Nonlinear Control of High-Order Modes in Single Asymmetric Nanoantennas

Hyperlenses and metalenses for far-field super-resolution imaging

Mode Imaging and Selection in Strongly Coupled Nanoantennas

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