SURFACE-PLASMONS

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Edge scattering of surface plasmons excited by scanning tunneling microscopy

Edge scattering of surface plasmons excited by scanning tunneling microscopy

The question of how these Au/ITO/glass interface plasmons are excited is an interesting one. It is known that the inelastic tunnel current of an STM excites both localized and propagating surface plasmons on air-gold film [25, 26]. The localized plasmons might in turn excite the “bottom” interface plasmons. Another possibility might be that the scattered light from the top interface is the excitation source. This last possibility may be ruled out, as the measured fringe shift as a function of the STM tip excitation position would not reflect the relative k SPP value of the Au/substrate plasmon. We thus propose that it is the localized surface plasmons directly beneath the STM tip that excite the Au/substrate plasmons which lead to the observed fringe shift.
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Radiative heat transfer at nanoscale mediated by surface plasmons for highly doped silicon.

Radiative heat transfer at nanoscale mediated by surface plasmons for highly doped silicon.

surface plasmons to the nanoscale radiative heat trans- fer. It is well-known that surface plasmons do not play any role in the heat transfer between two parallel metallic surfaces because they cannot be excited thermally. In- deed, typical energies of surface plasmons are larger than 2 eV. However, when dealing with highly doped silicon, the surface plasmon frequency is in the infrared. This ef- fect was extensively analysed by Fu and Zhang 20 . In this

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Influence of spatial dispersion on surface plasmons, nanoparticles and grating couplers

Influence of spatial dispersion on surface plasmons, nanoparticles and grating couplers

Recent experiments have shown that spatial dispersion may have a conspicuous impact on the response of plasmonic structures. This suggests that in some cases the Drude model should be replaced by more advanced descriptions that take spatial dispersion into account, like the hydro- dynamic model. Here we show that nonlocality in the metallic response affects surface plasmons propagating at the interface between a metal and a dielectric with high permittivity. As a direct consequence, any nanoparticle with a radius larger than 20 nm can be expected to be sensitive to spatial dispersion whatever its size. The same behavior is expected for a simple metallic grating allowing the excitation of surface plasmons, just as in Woods famous experiment. Finally, we care- fully set up a procedure to measure the signature of spatial dispersion precisely, leading the way for future experiments. Importantly, our work suggests that for any plasmonic structure in a high permittivity dielectric, nonlocality should be taken into account.
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Electron Acceleration by Relativistic Surface Plasmons in Laser-Grating Interaction

Electron Acceleration by Relativistic Surface Plasmons in Laser-Grating Interaction

In the optical or near-infrared frequency range, surface plasmons can be excited by laser light incident on a sharp material interface having a periodic modulation, e.g., a grating, to allow phase matching. However, most experi- ments so far have been restricted to intensities below 10 16 W=cm 2 [10] because of the prepulses inherent in high-power laser systems which can lead to an early disruption of the target structuring. The development of devices for ultrahigh contrast pulses [11,12] now allows us to explore the interaction with targets structured on a submicrometric scale at laser intensities high enough for the electron dynamics to become relativistic [13,14] . In particular, a strong increase of the cutoff energy of protons accelerated from the rear surface of grating targets was observed and related to surface plasmon-enhanced
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Sub-wavelength energy concentration with electrically generated mid-infrared surface plasmons

Sub-wavelength energy concentration with electrically generated mid-infrared surface plasmons

4 yannick.dewilde@espci.fr 5 raffaele.colombelli@u-psud.fr ∗ adel.bousseksou@u-psud.fr Abstract: While freely propagating photons cannot be focused below their diffraction limit, surface-plasmon polaritons follow the metallic surface to which they are bound, and can lead to extremely sub-wavelength energy volumes. These properties are lost at long mid-infrared and THz wavelengths where metals behave as quasi-perfect conductors, but can in principle be recovered by artificially tailoring the surface-plasmon dispersion. We demonstrate - in the important mid-infrared range of the electromagnetic spectrum - the generation onto a semiconductor chip of plasmonic excitations which can travel along long distances, on bent paths, to be finally focused into a sub-wavelength volume. The demonstration of these advanced functionalities is supported by full near-field characteriza- tions of the electromagnetic field distribution on the surface of the active plasmonic device.
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Resonant coupling between interface plasmons and surface plasmons at the junction between two simple metals

Resonant coupling between interface plasmons and surface plasmons at the junction between two simple metals

Thus, instead of assuming the form of a particular solution, we shall start from the basic equations, using again the hydrodynamical approach (which was the original t[r]

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Modal engineering of Surface Plasmons in apertured Au Nanoprisms

Modal engineering of Surface Plasmons in apertured Au Nanoprisms

Aurélien Cuche 1 , Sviatlana Viarbitskaya 1,2 , Jadab Sharma 1,† , Arnaud Arbouet 1 , Christian Girard 1 & Erik Dujardin 1 Crystalline gold nanoprisms of sub-micrometric size sustain high order plasmon modes in the visible and near infrared range that open a new realm for plasmon modal design, integrated coplanar devices and logic gates. In this article, we explore the tailoring of the surface plasmon local density of states (SP-LDOS) by embedding a single defect, namely a small hole, carved in the platelet by focused ion beam (FIB). The change in the SP-LDOS of the hybrid structure is monitored by two-photon luminescence (TPL) microscopy. The dependency of the two-dimensional optical field intensity maps on the linear polarization of the tightly focused femtosecond laser beam reveals the conditions for which the hole defect significantly affects the initial modes. A detailed numerical analysis of the spectral characteristics of the SP-LDOS based on the Green dyadic method clearly indicates that the hole size and location can be exploited to tune or remove selected SP modes.
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Etude du phénomène de la transition de spin dans les couches ultra-minces à l'aide des plasmons de surface

Etude du phénomène de la transition de spin dans les couches ultra-minces à l'aide des plasmons de surface

Recently, nano-objects and thin films displaying molecular spin crossover phenomenon have attracted much attention for their possible application as an active element in electronic or photonic devices. The change of the spin state is accompanied by a change in various physical properties of this molecule such as magnetic, optical, electrical and mechanical properties. However, the detection of the spin crossover in these materials at the nanoscale (thin films, nanoparticles, ...) makes for great difficulties, due to the small amount of the probed material, as well as due to the limited spatial resolution of the usual detection methods. To overcome these problems new methods have been developed in this thesis to study these materials at the nanoscale. Our approach is based on the resonance phenomena of localised surface plasmons and surface plasmon polaritons. These techniques use thin noble metal layers or patterned nanorod arrays, which allowed us to detect the refractive index change accompanying the spin crossover. In this thesis work, for the first time, we have been able to detect the spin crossover phenomenon in nanometric layers (down to 15 nm) for different materials, highlighting a refractive index variation of 10 -1 - 10 -2 . In addition, we have shown that the molecular spin state switching can be very efficiently triggered by a photo-thermal effect (plasmonic heating), which - in turn - allows for an active tuning of the plasmon resonance.
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Hybrid Plasmonic Mode by Resonant Coupling of Localized Plasmons to Propagating Plasmons in a Kretschmann Configuration

Hybrid Plasmonic Mode by Resonant Coupling of Localized Plasmons to Propagating Plasmons in a Kretschmann Configuration

2 - Institut d'Électronique Fondamentale, Université Paris Sud, CNRS Bât. 220, - Rue Ampère, 91405 Orsay, France ABSTRACT. Metal nanoparticles have the ability to strongly enhance the local electromagnetic field in their vicinity. Such enhancement is crucial for biomolecular detection and is used by techniques such as surface plasmon resonance detection or surface enhanced Raman scattering. For these processes, the sensitivity strongly depends on the electromagnetic field intensity confined around such nanoparticles. In this article, we have numerically studied an array of metallic nanocylinders, which can sustain Localized Surface Plasmons (LSP). However, the excitation wavelengths of the LSP are not tunable due to their limited dispersion. We have demonstrated a plasmonic mode, the Hybrid Lattice Plasmon (HLP), which is excited in such a periodic array by adding a uniform thin metallic film below it. This mode is a result of a harmonic coupling between the propagating surface plasmons present in such a metallic film with the Bragg waves of the array. It shows a strong confinement of the electromagnetic field intensity around the nanocylinders, similar to the LSP, but the dispersion of this HLP mode is, however, similar to that of the propagating plasmons, and thus can be tuned over a wide range of excitation wavelengths. The structure was fabricated using electron beam lithography, and characterized by a surface plasmon resonance setup. These experimental results show that the HLP mode can be excited in a classical Kretschmann configuration with a dispersion similar to the prediction of numerical simulations.
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Développement d'un biocapteur couplant la résonance des plasmons de surface et la microcalorimétrie pour le suivi des intéractions moléculaires à l'interface liquide/solide

Développement d'un biocapteur couplant la résonance des plasmons de surface et la microcalorimétrie pour le suivi des intéractions moléculaires à l'interface liquide/solide

Many biochemical reactions and biomolecular interactions can be characterized using biosensing microsystems. Biosensors are composed of a bioreceptor layer that interacts specially with a biomolecular target and a transducer that converts the biorecognition event into a measurable signal. Herein, the microfabrication steps for a hybrid (dual transduction) SPR-microcalorimeter biosensor are presented. The SPR transducer [18] measures reaction kinetics as well as Gibbs energies, while the micro- calorimeter [127] measures release or absorption of heat due to biomolecular interactions. The combi- nation of the two transduction techniques enables the experimental determination of the entropy of biomolecular interactions at a solid/liquid interface. The integration of the two transducers in a micro- system enables the characterization of biomolecular reactions with minute amounts of reagents com- pared to classical macro-scale calorimetric devices. The biosensor is based on a waveguide surface plasmons resonance (WSPR) sensor [79] coupled to a microcalorimetric sensor.[128] The biorecognition layer is based on neutravidin/biotin interaction. [129,130]
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Ab initio study of electronic surfaces states and plasmons of gold : role of the spin-orbit coupling and surface geometry.

Ab initio study of electronic surfaces states and plasmons of gold : role of the spin-orbit coupling and surface geometry.

Introduction The birth of plasmonics took place at the very beginning of the twentieth century, when Wood [1] observed an unusual phenomenon during the study of light distribution in a diffraction grating spectrum. Lord Rayleigh attempted to explain this phenomenon, how- ever it was not until 1941 when Fano [2] associated the so-called Wood anomalies with surface waves and suggested that they are linked to the dielectric properties of the mate- rial. Later on, Pines [3] and Ritchie [4] have developed the theory of plasma oscillations in solids and have suggested that careful investigation of the low energy losses in a sin- gle metal should be made. The first experimental evidence of plasma oscillations on an aluminum surface was demonstrated by Powell and Swan [5] a few years later. This phenomenon is called surface plasmon - a collective oscillation of the free electron den- sity similar to plasma oscillations observed in ionized gases [6]. As collective phenomena, plasmons are driven by the Coulomb interaction between electrons in contrast with single- particle excitations that e.g. involve the dipolar transition of a single electron from an occupied to an unoccupied state. After this discovery, surface plasmons have been widely studied and characterized both experimentally and theoretically for various materials and systems. Nowadays, noble metals such as gold and silver are the most used materials for plasmonics applications as they have well defined plasmons and possess other useful properties, for instance gold is very stable and is not easily oxidized.
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Plasphonics : local hybridization of plasmons and phonons

Plasphonics : local hybridization of plasmons and phonons

In summary, the hybridization between the surface plasmons of a metallic nano-antenna and the surface phonons of an heteropolar semiconductor has been studied theoretically using both an analytical approach and numerical simulations. This hybridization is governed by the plas- monic and phononic near-fields and may lead to Rabi-splitted plasphonic excitations. It allows a fine tuning of optical resonances and can be exploited for far-infrared based sensing. The mixed character of the plasphonic excitations has also been pointed out from the simulated electric near-field maps. In particular, we found that, in the strong coupling regime, the electric field enhancement at the nano-antenna ends is one order of magnitude larger than the one ob- tained with a non-polar semiconductor surface. This allows us introducing the concept of active
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Correlated blinking of fluorescent emitters mediated by single plasmons

Correlated blinking of fluorescent emitters mediated by single plasmons

Silver nanowires have been suggested as broadband waveg- uides, supporting surface plasmons, which propagate over distances of several micrometers along the wire axis [ 4 ]. The strong electromagnetic field confinement, which characterizes surface plasmons, leads to large enhancements of the spon- taneous emission rate of emitters near-field coupled to silver nanowires. Such enhancement goes along with an efficient coupling into the guided surface plasmon mode, paving the way to applications in quantum nanophotonics [ 5 – 7 ]. It has also been shown that the coupling of single photon emitters, e.g., semiconductor quantum dots (QD) or nitrogen-vacancy defects, to a silver nanowire, generates single surface plasmons exhibiting properties similar to those of single photons
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Ponderomotive effects in the femtosecond plasmon-assisted photoelectric effect in bulk metals: Evidence for coupling between surface and interface plasmons

Ponderomotive effects in the femtosecond plasmon-assisted photoelectric effect in bulk metals: Evidence for coupling between surface and interface plasmons

共Received 18 October 2007; published 12 December 2007 兲 The existence of ponderomotive acceleration effects in the metal bulk has been experimentally demonstrated in the context of the femtosecond plasmon-assisted multiphoton photoelectric effect in metal systems. The resulting electron energy spectra show that these effects essentially depend on the coupling between the surface and interface plasmons. While the essential part played by the ponderomotive force of the surface plasmon is to accelerate the photoelectrons in the vacuum, the dramatic enhancement of the photoelectron production and the angular dependence in the photoemission process mainly result from ponderomotive effects in the metal bulk.
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Propriétés optiques et analytiques des nanotrous : vers la conception de biocapteurs en résonance des plasmons de surface localisés

Propriétés optiques et analytiques des nanotrous : vers la conception de biocapteurs en résonance des plasmons de surface localisés

d’indice de réfraction η a , créant le changement d’indice de réfraction nécessaire pour causer le changement de longueur d’onde transmise par les nanotrous. Les agents de reconnaissance peuvent être des protéines, de l’acide désoxyribonucléique (DNA) ou des anticorps, offrant aux techniques basées sur le SPR la possibilité de détecter des analytes se liant à ces biomolécules. Cette technique est avantageuse, car elle permet la mesure de molécules n’ayant pas de signature spectroscopique sensible et spécifique. En plus d’être sensible pour un grand nombre d’analytes (détecteur quasi universel), le plasmon de surface qui peut être excité à angle droit par l’utilisation d’un film perforé permet les mesures en transmission, telle qu’avec un simple instrument de spectroscopie UV-Vis. De plus, puisque le plasmon de surface est dans la région spectrale entre λ = 500 et λ = 900 nm, le spectre en transmission peut être fait dans des milieux complexes qui limitent habituellement les mesures en transmission, dû à l’absorption de la lumière par les fluides biologiques à des longueurs d’onde inférieures à λ = 500 nm. Malgré que ces avantages soient intéressants, il n’existe toujours pas de consensus sur le type de nanostructures à employer. Il est donc intéressant de faire des recherches pouvant utiliser tous ces avantages et contribuer aux connaissances concernant le choix de nanostructures à employer dans la conception de biocapteurs. C’est dans cette approche que ce projet a été élaboré.
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Plasmons dans un potentiel unidimensionnel<br />Etude par spectroscopie Raman de fils quantiques gravés

Plasmons dans un potentiel unidimensionnel<br />Etude par spectroscopie Raman de fils quantiques gravés

Advances in the microfabrication techniques of semiconductors have given access to devices with one-dimensional (1D) confinement of electrons [1]. Among the different techniques to achieve the lateral confinement, deep reactive ion etching (RIE) provides the greatest flexibility to realize arbitrary geometries. However, it suffers from the limitations in the lowest size easily realizable and from the presence of a high density of etching defects created on the lateral sidewalls of the quantum well. These defects are likely to capture the mobile carriers from the wire and depletion length of the order of 500nm have been reported [2], preventing the realization of well-controlled quasi-one-dimensional electron gas (1DEG). We have shown previously from the observation by electronic Raman scattering of narrow lines related to the laterally confined plasmons that an electrochemical oxidation after the RIE process leads to high quality 1DEGs with lateral size below 100nm [3,4]. In this work, we report on a quantitative comparison of Raman scattering (RS) and far infrared (FIR) determinations of the plasmon excitations. In RS we deduce the abrupt lateral distribution of free electrons and the critical width where their density vanishes from the dispersion along the wire axis of several laterally confined plasmons. In FIR we deduce the nearly parabolic shape of the external confinement potential and a significantly larger critical width from the position and the intensity of the single magnetoplasmon resonance. All experimental data are analysed in terms of a semiclassical electrostatic approach.
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Approche expérimentale et théorique de la diffusion Raman exaltée : résonance des plasmons de surface et effet de pointe

Approche expérimentale et théorique de la diffusion Raman exaltée : résonance des plasmons de surface et effet de pointe

La résolution latérale limitée à quelques centaines de nanomètres ainsi que la faible efficacité du processus de diffusion représentent deux limites d’importance. Dans l’optique d’explorer la matière à l’échelle nanométrique, la spectroscopie Raman peut alors paraître inadaptée. Les exigences liées à l’étude des nano-objets imposent donc d’augmenter significativement le signal de diffusion et d’atteindre des résolutions latérales très inférieures à la longueur d’onde de la lumière incidente. A la fin des années 70, Fleischman et al. [3] observèrent une augmentation drastique du signal de diffusion Raman de la molécule de pyridine adsorbée sur une électrode d’argent. Par la suite ce phénomène d’exaltation fût attribué aux propriétés optiques des métaux nobles (argent, or, cuivre etc.) et aux structures de dimensions nanométriques à la surface des substrats métalliques. Il fût nommé effet SERS (Surface Enhanced Raman Scattering). Au cours de ces quarante dernières années, en démontrant notamment que l’intensité du signal de diffusion Raman peut être augmentée de 13 à 15 ordres de grandeurs (variable selon les auteurs), on a ouvert la voie de l’étude de la molécule (ou du nano-objet) isolée.
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Capteur à fibre optique basé sur le principe de Résonance de Plasmons de Surface : optimisation pour la détection d'espèces chimiques

Capteur à fibre optique basé sur le principe de Résonance de Plasmons de Surface : optimisation pour la détection d'espèces chimiques

Ainsi, si l’on approche ces sources au voisinage ultime de l’interface à investiguer (d’une distance de l’ordre de quelques dizaines de nm ou moins), un PS est susceptible d’être couplé, si là encore, la condition de résonance est satisfaite (fréquence de la lumière adapté…). Pour les capteurs SPR qui est l’objet de cette thèse, ils ont été principalement réalisés depuis leurs premières utilisations avec des coupleurs massifs, notamment avec les deux configurations les plus connues, la configuration de Kretschmann [28-31], et celle de Otto [32]. L’utilisation de guides d’ondes [33,34], de réseaux [35-37], de canaux de lumières (‘light pipes’) [38] a aussi été proposée comme alternative aux systèmes de prismes. Cependant tout récemment, plusieurs équipes de recherche ont utilisé des fibres optiques modifiées pour bénéficier d’avantages attractifs tels que le contrôle à distance, les analyses en temps réel mais aussi in situ ou in vivo. D’autres avantages existent avec ces Capteurs à Fibres Optiques fondés sur le principe de Résonance Plasmon de Surface (facilité de sonder dans des environnements à risques, miniaturisation des dispositifs, coût réduit que nous détaillerons dans le chapitre II.
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Conception d'un système de biodétection à base de résonance des plasmons de surface appliqué à la mesure d'activité cellulaire

Conception d'un système de biodétection à base de résonance des plasmons de surface appliqué à la mesure d'activité cellulaire

Utilises de plus en plus couramment en laboratoire, certains sont meme disponibles commercialement, en particulier les capteurs par resonance de plasmons de surface (SPR). Phenomene d'a[r]

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Façonnage de modes plasmons dans des colloïdes d'or

Façonnage de modes plasmons dans des colloïdes d'or

avec le changement de teinte du rose au bleu observé au cours de l’auto-assemblage. Le large pic de la courbe bleue indique qu’il y a bien eu formation de ces structures linéaires car il correspond à un mode plasmon résultant du couplage entre les électrons qui oscillent à la surface de chacune des nanoparticules le long de l’axe de la chaîne. Un enregistrement à intervalles de temps réguliers du spectre d’absorption d’une solution de particules d’or après ajout de MEA est effectué dans la référence [58]. Ce time-laspe nous éclaire sur l’auto-assemblage et sur sa cinétique. Après quelques heures, le pic à 520 nm décroît et un second maximum apparaît à 620 nm. Tandis que le premier pic continue de décroître en intensité, le second devient de plus en plus intense tout en se décalant vers le rouge. Après 72h, il se stabilise à un peu plus de 700 nm. Cette évolution de la position et de l’amplitude du pic longitudinal indique que des fragments de chaîne de taille croissante se forment. Le fait que le pic ne se décale pas indéfiniment dans l’infrarouge est dû au désordre des chaînes qui limite le couplage entre plasmons à un nombre restreint de nanoparticules. La décroissance d’intensité du pic à 520 nm témoigne elle-aussi de l’auto-assemblage des particules puisque seules les directions de polarisation perpendiculaires à l’axe des chaînes excitent ce mode transverse et contribuent à l’ab- sorption à cette longueur d’onde. Le léger décalage vers le rouge est peut-être dû à la modification de l’indice de réfraction du milieu environnant. En effet, le MEA a probablement un indice optique élevé par rapport à l’eau, car les auteurs de la référence [58] ont dû fixer, en accord avec les données expérimentales sur des composés similaires, l’indice de réfaction du milieu environnant à 1,7 dans leur programme de simulation DDA de spectres d’extinction des chaînes pour reproduire fidèlement le spectre expérimental. De plus, pour obtenir le pic du mode longitudinal aux alentours de 700 nm, il a fallu introduire du désordre dans la chaîne linéaire sur laquelle portait le calcul. Cependant, le pic du spectre simulé est beaucoup plus étroit que ce qui a été mesuré au spectromètre. En s’appuyant sur des spectres d’extinction simulés de motifs constituant les chaînes (boucle, zig-zag et bifurcation), les auteurs suggèrent que l’élargissement spectral du pic longitudinal est le résultat de la contribution de chacun de ces motifs à la réponse globale des chaînes en solution.
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