Ultra‐fast nano‐optics

Vasa, Parinda; Ropers, Claus; Pomraenke, R.; Lienau, Christoph

doi:10.1002/lpor.200810064

Cited by 72 publications

(55 citation statements)

References 149 publications

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“…This tip geometry provides near-optimal excitation and collection properties for nano-Raman and nano-IR/FTIR hyperspectral imaging and also enables measurements such as white-light nano-ellipsometry/interferometric mapping of dielectic functions, nonlinear optical experiments that involve multiple optical frequencies (such as sum-frequency and secondharmonic generation), coherent anti-Stokes and stimulated Raman spectroscopy, as well as other ultrafast pump-probe investigations of local dynamics [82]. Fig.…”

Section: Resultsmentioning

confidence: 99%

Plasmonic near-field probes: a comparison of the campanile geometry with other sharp tips

Bao¹,

Staffaroni²,

Bokor³

et al. 2013

Opt. Express

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Efficient conversion of photonic to plasmonic energy is important for nano-optical applications, particularly imaging and spectroscopy. Recently a new generation of photonic/plasmonic transducers, the 'campanile' probes, has been developed that overcomes many shortcomings of previous near-field probes by efficiently merging broadband field enhancement with bidirectional coupling of far- to near-field electromagnetic modes. In this work we compare the properties of the campanile structure with those of current NSOM tips using finite element simulations. Field confinement, enhancement, and polarization near the apex of the probe are evaluated relative to local fields created by conical tapered tips in vacuum and in tip-substrate gap mode. We show that the campanile design has similar field enhancement and bandwidth capabilities as those of ultra-sharp metallized tips, but without the substrate and sample restrictions inherent in the tip-surface gap mode operation often required by those tips. In addition, we show for the first time that this campanile probe structure also significantly enhances the radiative rate of any dipole emitter located near the probe apex, quantifying the enhanced decay rate and demonstrating that over 90% of the light radiated by the emitter is "captured" by this probe. This is equivalent to collecting the light from a solid angle of ~3.6 pi. These advantages are crucial for performing techniques such as Raman and IR spectroscopy, white-light nano-ellipsometry and ultrafast pump-probe studies at the nanoscale.

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Section: Resultsmentioning

confidence: 99%

Plasmonic near-field probes: a comparison of the campanile geometry with other sharp tips

Bao¹,

Staffaroni²,

Bokor³

et al. 2013

Opt. Express

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“…Clearly, graphene is the ultimate thin surface layer. This fact, together with the ability of tuning the value of the chemical potential by an external gate, makes this system particularly interesting, since the formation of this type of electromagnetic surface waves can by controlled externally.From the point of view of applications, surface plasmonpolaritons can be explored in plasmon sensors [14] and highresolution imaging [15], as well as for the miniaturization of photonics components [16][17][18]. In this Letter, we show that it is feasible to achieve a sharp resonance of the attenuation of an electromagnetic wave by transferring its energy into the excitation of surface plasmon-polaritons in graphene.…”

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confidence: 91%

Mechanism for graphene-based optoelectronic switches by tuning surface plasmon-polaritons in monolayer graphene

Bludov

Vasilevskiy

Peres

2010

EPL

117

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Abstract. -It is shown that one can explore the optical conductivity of graphene, together with the ability of controlling its electronic density by an applied gate voltage, in order to achieve resonant coupling between an external electromagnetic radiation and surface plasmon-polaritons in the graphene layer. This opens the possibility of electrical control of the intensity of light reflected inside a prism placed on top of the graphene layer, by switching between the regimes of total reflection and total absorption. The predicted effect can be used to build graphene-based opto-electronic switches.Among the many promised graphene dreams [1-3], the possibility of exploring the electronic, thermal, and mechanical properties of graphene, having in view a new generation of optoelectronic devices, is one of the most exciting of those dreams. Understanding the fundamental physics of the interaction of electrons (in graphene) with an electromagnetic field is a key step toward the realization of such devices.The optical response of graphene has been an active field of research, both experimental [4][5][6][7] and theoretical [8][9][10], and much is already understood. From the theoretical point of view, the independent electron approximation predicts that the real part of optical conductivity of graphene, at zero temperature, has the form σ = σ 0 θ( ω − 2µ), where σ 0 = πe 2 /(2 ) is the AC universal conductivity of graphene, ω is the photon energy, µ is the chemical potential, and θ(x) is the Heaviside step function. The imaginary part of the conductivity is finite everywhere, as long as µ is also finite [11]. For zero chemical potential, the experiments [4,5,7] confirm the independent electron model predictions. On the other hand, for finite chemical potential and ω < 2µ, the experiments show a substantial absorption in this energy range, at odds with the theoretical prediction. In simple terms, the real part of the conductivity, as measured experimentally, follows roughly the formula, where E D is the energy at which the Drude peak starts developing. Below E D , the optical response increases dramatically. The difference between experiment and theory can be explained by both interband and intra-band scattering, due to impurities and electronelectron interactions. In what concerns our present study, the deviations seen in the experimental data are actually vital for the effect we discuss below, and therefore the calculations we present below use the experimentally measured conductivity of graphene. The exact form of σ(ω) below the 2µ threshold is essential for the particular type of interaction of the electrons in graphene with an electromagnetic field leading to the formation of surface plasmon-polaritons [12].Surface plasmon-polariton (SPP) is an evanescent electromagnetic wave induced by the coupling of the electromagnetic field to the electrons near the surface of a metal or a semiconductor. Its amplitude decays exponentially at both sides of the interface. The SPP properties are determined by the dielectric funct...

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“…Such intense electron emission was only seen when polarizing the incident pulses along the taper axis, clearly illustrating the polarization sensitivity of the field enhancement promoting electron generation. By comparing the electron flux from the tip apex to that from the shaft, we could estimate local field enhancement factors of about 10 for our gold tips [131]. Interferometric autocorrelation of the laser pulses detected via the electron signal [26] indicated that electron emission from the tip occurs on time scales shorter than our resolution of about 10 fs.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Nano‐Focusing for Imaging and Spectroscopy with Electrons and Light

Lienau

Raschke

Ropers

2014

Attosecond Nanophysics

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There is an urgent need for improved or conceptually new, ultrafast microscopy techniques which combine the best spatial and temporal resolutions possible. Techniques need to be developed which fuse nanometer-or atomic-scale imaging, such as scanning probe microscopy with ultrafast, femto-or attosecond time resolution, which is now commonplace in ultrafast science. A multitude of highly relevant, technological processes, such as the conversion of sunlight into electrical [1-3] or chemical energy [4-6], involves, on a microscopic level, the concerted motion of electrons and atomic nuclei. These processes are therefore governed by microscopic dynamics taking place on ultrashort and ultrasmall scales. Our ability to design and optimize such devices thus crucially depend on a detailed analysis and understanding of the spatio-temporal dynamics of charge, spin and atomic lattice excitations.A broad range of time-resolved microscopy techniques are currently under development or already in use. These techniques include X-ray diffraction/microscopy with large-scale free-electron lasers [7][8][9] or tabletop sources [10,11], ultrafast electron diffraction [12][13][14][15] or microscopy [16,17], time-resolved photoelectron emission microscopy [18-20] (Chapter 10), ultrafast, aperture-based [21][22][23][24][25] or aperture-less near-field scanning optical microscopy [26][27][28], and femtosecond scanning tunneling microscopy [29][30][31][32].So far, most of the techniques mentioned earlier provide either a limited temporal or spatial resolution, and the implementation of microscopy techniques with true nanometer and (sub-)femtosecond resolution [33] remains a formidable challenge. A fundamental problem in many of these approaches is the generation of sufficiently bright and temporally short light or electron pulses which are both coherent and energetically tunable [34].

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Ultra‐fast nano‐optics

Cited by 72 publications

References 149 publications

Plasmonic near-field probes: a comparison of the campanile geometry with other sharp tips

Plasmonic near-field probes: a comparison of the campanile geometry with other sharp tips

Mechanism for graphene-based optoelectronic switches by tuning surface plasmon-polaritons in monolayer graphene

Ultrafast Nano‐Focusing for Imaging and Spectroscopy with Electrons and Light

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