Excitation of Mesoscopic Plasmonic Tapers by Relativistic Electrons: Phase Matching <i>versus</i> Eigenmode Resonances

Talebi, Nahid; Sigle, Wilfried; Vogelgesang, Ralf; Esmann, Martin; Becker, Simon F.; Lienau, Christoph; Aken, Peter A. van

doi:10.1021/acsnano.5b03024

Cited by 62 publications

(81 citation statements)

References 39 publications

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“…To directly probe this local field enhancement for conical gold tapers in a very broad spectral range, we have used electron energy loss spectroscopy (EELS) [86] and energy-filtered transmission electron microscopy (EFTEM) [103]. In these measurements, a monochromatic beam of relativistic electrons at 200 keV kinetic energy propagates parallel to the x-axis, perpendicular to the taper axis, which coincides with the z-axis.…”

Section: Plasmonic Eigenmodes Of Circular Wires and Tapersmentioning

confidence: 99%

“…The resulting images can be approximated as [86] and provide a map of the x-component of local electric field at frequency ω projected onto the wave function of the monochromatic energy beam, propagating with velocity V. Near the taper apex, the oscillatory term is essentially constant, and the images probe the vector component of the local electric near field that is pointing along the propagation direction of the incident electron beam.…”

Section: Plasmonic Eigenmodes Of Circular Wires and Tapersmentioning

confidence: 99%

“…When coupling ultrafast laser pulses to propagating SPPs at the shaft of those tapers, nanometre-localized light spots with pulse durations as short as 10 fs are created at the taper apex with high efficiency [42,76]. Consequently, the optical properties of such antennas have been studied in considerable detail, both experimentally and theoretically, during the past several years [42,63,64,70,[75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90][91].…”

Section: Introductionmentioning

confidence: 99%

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Plasmonic nanofocusing – grey holes for light

Groß

Esmann

Becker

et al. 2016

Advances in Physics: X

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Improving the resolution and sensitivity in all-optical microscopy and spectroscopy is inevitably one of the most important challenges in contemporary optical and nanoscience. Here, we discuss a novel approach, plasmonic nanofocusing, towards broadband, coherent all-optical microscopy with ultrahigh temporal and spatial resolution. The conceptual idea is to launch radially symmetric surface plasmon polariton modes onto the shaft of a sharp, conical metal taper. While propagating towards the apex of the pointed taper, the spatial extent of the plasmonic mode gradually shrinks, from several microns in diameter to a spot size of less than 10 nm at the pointed apex of the conical taper. Concomitantly, the local field amplitude of the plasmon mode gradually increases, resulting in a pronounced field enhancement at the apex and -thus -a bright and spatially isolated coherent light source with dimensions far below the diffraction limit. In this review, we characterize the optical properties of such three-dimensional conical metal tapers and demonstrate nanofocusing of radially symmetric plasmon modes. We use this nanolight source for coherent light scattering spectroscopy and demonstrate the sensitivity enhancement resulting from the pronounced spatial field confinement. It is shown that such off-resonant plasmonic nanoantennas facilitate the creation of nanofocused light spots with few-cycle time resolution. As a first application of this ability to nanolocalize ultrashort plasmon wavepackets, we demonstrate remotely-triggered multiphoton-induced photoemission from the very apex of the taper and implement this novel ultrafast electron gun in a point-projection electron microscope. Our results not only indicate the favourable optical properties of this plasmonic nanolens but also suggest that it may find interesting applications in ultrafast scanning optical spectroscopy and might enable new types of ultrafast electron holography and scanning tunnelling microscopy.

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Section: Plasmonic Eigenmodes Of Circular Wires and Tapersmentioning

confidence: 99%

Section: Plasmonic Eigenmodes Of Circular Wires and Tapersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Plasmonic nanofocusing – grey holes for light

Groß

Esmann

Becker

et al. 2016

Advances in Physics: X

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“…More interestingly, photonic crystals and toroidal cavities designed in a precise way for quenching the radiation from dyes can provide a new path for nonradiative energy transfer between the adjacent elements, by incorporating the concept of anapoles. Additionally, we anticipate that the coupling of the whispering gallery modes of tapers and fibers [27,161] to the axial toroidal moments at the apex of a SNOM tip will be an interesting option to introduce new near-field microscopes with higher efficiencies and long-range coupling probabilities compared to the generally used SNOM tips, which are based on dipoledipole interactions. Such a configuration might be used to probe the magnetic field, in a competing configuration with well-known spin-coded SNOM tips [72].…”

Section: Discussionmentioning

confidence: 99%

“…Not only such expansion sets help us to analytically find solutions to simple problems, but they also help us to simplify or find approximate solutions to complicated systems. Among the so-called expansion sets that physicists routinely use are Rayleigh expansion sets [10,25], Eigenmode expansion sets [11,26,27], and multipole expansion sets [28]. The multipole expansion, which is based on the expansion of either potentials [29][30][31] or fields [32,33], has several applications in classical electrodynamics, such as finding solutions to inverse problems [34][35][36], reconstruction of images [37], and in general, decomposition of induced charges into a set of localized charge distributions with well-known near-field and farfield characteristics.…”

Section: Families Of Multipoles In Electrodynamicsmentioning

confidence: 99%

Theory and applications of toroidal moments in electrodynamics: their emergence, characteristics, and technological relevance

2017

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Dipole selection rules underpin much of our understanding in characterization of matter and its interaction with external radiation. However, there are several examples where these selection rules simply break down, for which a more sophisticated knowledge of matter becomes necessary. An example, which is increasingly becoming more fascinating, is macroscopic toroidization (density of toroidal dipoles), which is a direct consequence of retardation. In fact, dissimilar to the classical family of electric and magnetic multipoles, which are outcomes of the Taylor expansion of the electromagnetic potentials and sources, toroidal dipoles are obtained by the decomposition of the moment tensors. This review aims to discuss the fundamental and practical aspects of the toroidal multipolar moments in electrodynamics, from its emergence in the expansion set and the electromagnetic field associated with it, the unique characteristics of their interaction with external radiations and other moments, to the recent attempts to realize pronounced toroidal resonances in smart configurations of meta-molecules. Toroidal moments not only exhibit unique features in theory but also have promising technologically relevant applications, such as data storage, electromagnetic-induced transparency, unique magnetic responses and dichroism.

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Investigation of Plasmonic Modes of Gold Tapers by EELS

Guo

Talebi

Sigle

et al. 2016

European Microscopy Congress 2016: Proceedings

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Plasmonic tapers have been studied intensively due to the ability of adiabatically coupling the propagating surface plasmon polaritons along their shaft to the nanolocalized plasmons at their apex. Therefore, they can find applications in the fields of sub‐diffraction‐limit nanofocusing, ultrafast photoemission, and near‐field optical microscopy. We investigate the plasmonic modes of three‐dimensional single crystalline gold tapers by means of EELS (electron energy loss spectroscopy) and FDTD (finite‐difference time‐domain) numerical calculation. We observe a broadband excitation in the proximity of the apex and discrete higher‐order azimuthal plasmonic modes along the taper shaft in the gold taper with an opening angle of ~45°. Interestingly, the energy dispersions of these higher‐order plasmonic modes are roughly proportional to the inverse local radius. The importance of phase‐matching between electron field and radiative taper modes in mesoscopic structure is demonstrated [1]. The role of an alternative mechanism suggested by Schröder et al. [2] was analyzed by systematically studying changes in the dispersion of higher‐order plasmonic modes of gold tapers for different opening angles.

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Excitation of Mesoscopic Plasmonic Tapers by Relativistic Electrons: Phase Matching versus Eigenmode Resonances

Cited by 62 publications

References 39 publications

Plasmonic nanofocusing – grey holes for light

Plasmonic nanofocusing – grey holes for light

Theory and applications of toroidal moments in electrodynamics: their emergence, characteristics, and technological relevance

Investigation of Plasmonic Modes of Gold Tapers by EELS

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