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1
Berger, T., J. Konheiser, A. V. Anikeev, et al. "Study of high temperature and high density plasmoids in axially symmetrical magnetic fields." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-27870.
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Within the framework of an Institutional Partnership of the Alexander von Humboldt Foundation, the Budker Institute of Nuclear Physics Novisibirsk (BINP) and Forschungszentrum Dresden-Rossendorf worked together in a joint project devoted to the research at the coupled GDT-SHIP facility of the BINP with the focus on the study of plasma phenomena within the SHIP mirror section. The project began at July 1st, 2005 and ended on August 30th, 2008. It included work packages of significant theoretical, computational and analyzing investigations. The focus of this final report is on the presentation of results achieved whereas the work that was done is described briefly only. Chapter 2 illustrates the GDT-SHIP facility and describes shortly the planned topics of the SHIP plasma research. Chapter 3 explains the main extensions and modifications of the Integrated Transport Code System (ITCS) which were necessary for the calculations of the fast ion and neutral gas particle fields in SHIP, describes briefly the scheme of computations and presents significant results of pre-calculations from which conclusions were drawn regarding the experimental program of SHIP. In chapter 4, the theoretical and computational investigations of self-organizing processes in two-component plasmas of the GDT-SHIP device are explained and the results hitherto achieved are presented. In chapter 5, significant results of several experiments with moderate and with enhanced plasma parameters are presented and compared with computational results obtained with the ITCS. Preparing neutron measurements which are planned for neutron producing experiments with deuterium injection, Monte Carlo neutron transport calculations with the MCNP code were also carried out. The results are presented. Finally, from the results obtained within the joint research project important conclusions are drawn in chapter 6.
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Berger, T., J. Konheiser, A. V. Anikeev, et al. "Study of high temperature and high density plasmoids in axially symmetrical magnetic fields." Forschungszentrum Dresden-Rossendorf, 2009. https://hzdr.qucosa.de/id/qucosa%3A21614.
Full textAbstract:
Within the framework of an Institutional Partnership of the Alexander von Humboldt Foundation, the Budker Institute of Nuclear Physics Novisibirsk (BINP) and Forschungszentrum Dresden-Rossendorf worked together in a joint project devoted to the research at the coupled GDT-SHIP facility of the BINP with the focus on the study of plasma phenomena within the SHIP mirror section. The project began at July 1st, 2005 and ended on August 30th, 2008. It included work packages of significant theoretical, computational and analyzing investigations. The focus of this final report is on the presentation of results achieved whereas the work that was done is described briefly only. Chapter 2 illustrates the GDT-SHIP facility and describes shortly the planned topics of the SHIP plasma research. Chapter 3 explains the main extensions and modifications of the Integrated Transport Code System (ITCS) which were necessary for the calculations of the fast ion and neutral gas particle fields in SHIP, describes briefly the scheme of computations and presents significant results of pre-calculations from which conclusions were drawn regarding the experimental program of SHIP. In chapter 4, the theoretical and computational investigations of self-organizing processes in two-component plasmas of the GDT-SHIP device are explained and the results hitherto achieved are presented. In chapter 5, significant results of several experiments with moderate and with enhanced plasma parameters are presented and compared with computational results obtained with the ITCS. Preparing neutron measurements which are planned for neutron producing experiments with deuterium injection, Monte Carlo neutron transport calculations with the MCNP code were also carried out. The results are presented. Finally, from the results obtained within the joint research project important conclusions are drawn in chapter 6.
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Granier, Camille. "Nouveaux développements sur la théorie des instabilités des feuilles de courant dans les plasmas non-collisionels." Electronic Thesis or Diss., Université Côte d'Azur, 2022. http://www.theses.fr/2022COAZ4109.
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La reconnexion magnétique est une modification de la topologie du champ magnétique, responsable de la libération explosive d'énergie magnétique dans les plasmas astrophysiques, comme dans le cas des orages magnétosphériques et des éjections de masse coronale, ainsi que dans les plasmas de laboratoire, comme dans le cas des crashs en dents de scie dans les tokamaks. Dans les plasmas sans collisions comme, par exemple, la magnétosphère et le vent solaire, l'inertie des électrons devient particulièrement pertinente pour provoquer la reconnexion dans les régions de courant localisé intense, appelées feuilles de courant. Dans ces environnements non collisionnels, la température peut souvent être anisotrope et les effets à l'échelle électronique sur le processus de reconnexion peuvent devenir non négligeables.Dans cette thèse, la stabilité des feuilles de courant bidimensionnelles dans des plasmas sans collisions avec un fort champ guide est analysée sur la base de modèles gyrofluides assumant des ions froids. Ces modèles peuvent prendre en compte une anisotropie de température d'équilibre, et un βe fini. Ce dernier est un paramètre correspondant au rapport entre la pression cinétique électronique d'équilibre et la pression magnétique.Nous dérivons et analysons une relation de dispersion pour le taux de croissance des modes tearing sans collisions tenant compte de l'anisotropie de la température d'équilibre des électrons. Les prédictions analytiques sont testées par des simulations numériques, montrant un très bon accord quantitatif.Dans le cas isotrope, en tenant compte des effets βe finis, nous observons une stabilisation du taux de croissance du mode tearing lorsque les effets du rayon de Larmor fini des électrons deviennent pertinents. Dans la phase non linéaire, des phases de ralentissement et des phases d'accélération sont observées, de manière similaire à ce qui se produit en présence d'effets de rayon de Larmor fini ionique.Nous étudions également les conditions de stabilité marginale des feuilles de courant secondaires, pour le développement de plasmoïdes, dans des plasmas sans collisions. Dans le régime isotrope βe → 0, nous analysons la géométrie qui caractérise le feuillet de courant, et identifions les conditions pour lesquelles elle devient instable à l'instabilité plasmoïde. Notre étude montre que des plasmoïdes peuvent être obtenus, dans ce contexte, à partir de feuille de courants aillant un rapport d'aspect beaucoup plus petit que dans le régime collisionnel. De plus, nous étudions la formation de plasmoïdes en comparant les simulations gyrofluides et gyrocinétiques.Ceci a permis de montrer que l'effet de βe favorise l'instabilité plasmoïde. Enfin, nous étudions l'impact de la fermeture appliquée sur les moments, effectuée lors de la dérivation du modèle gyrofluide, sur la distribution et la conversion de l'énergie lors de la reconnexion<br>Magnetic reconnection is a change of topology of the magnetic field, responsible for explosive release of magnetic energy in astrophysical plasmas, as in the case of magnetospheric substorms and coronal mass ejections, as well as in laboratory plasmas, which is the case of sawtooth crashes in tokamaks. In collisionless plasmas as, for instance, the magnetosphere and the solar wind, electron inertia becomes particularly relevant to drive reconnection at regions of intense localized current, denoted as current sheets. In these non-collisional environments, the temperature can often be anisotropic and effects at the electron scale on the reconnection process can become non-negligible.In this thesis, the stability of two-dimensional current sheets, with respect to reconnecting perturbations, in collisionless plasmas with a strong guide field is analysed on the basis of gyrofluid models assuming cold ions. These models can take into account an equilibrium temperature anisotropy,and a finite βe, a parameter corresponding to the ratio between equilibrium electron kinetic pressure and magnetic pressure.We derive and analyze a dispersion relation for the growth rate of collisionless tearing modes accounting for equilibrium electron temperature anisotropy. The analytical predictions are tested against numerical simulations, showing a very good quantitative agreement.In the isotropic case, accounting for finite βe effects, we observe a stabilization of the tearing growth rate when electron finite Larmor radius effects become relevant. In the nonlinear phase, stall phases and faster than exponential phases are observed, similarly to what occurs in the presence of ion finite Larmor radius effects.We also investigate the marginal stability conditions of secondary current sheets, for the development of plasmoids, in collisionless plasmas. In the isotropic βe → 0 regime, we analyze the geometry that characterizes the reconnecting current sheet, and identify the conditions for which it is plasmoid unstable. Our study shows that plasmoids can be obtained, in this context, from current sheets with an aspect ratio much smaller than in the collisional regime. Furthermore, we investigate the plasmoid formation comparing gyrofluid and gyrokinetic simulations.This made it possible to show that the effect of finite βe, promotes the plasmoid instability. Finally, we study the impact of the closure applied on the moments, performed during the derivation of the gyrofluid model, on the distribution and conversion of energy during reconnection<br>La riconnessione magnetica è un cambiamento nella topologia delcampo magnetico, responsabile del rilascio esplosivo di energia magnetica nei plasmiastrofisici, come nelle tempeste magnetosferiche e nelle espulsioni di massa coronale,nonché nei plasmi di laboratorio, come nel caso delle oscillazioni a dente di sega neitokamak. Nei plasmi non-collisionali come, ad esempio, la magnetosfera e il vento solare,l’inerzia elettronica diventa particolarmente efficace nel causare la riconnessionein regioni di corrente intensa e localizzata, detti strati di corrente. In tali plasmi noncollisionali,la temperatura può essere spesso anisotropa e gli effetti su scala elettronicasul processo di riconnessione possono diventare non trascurabili.In questa tesi, viene analizzata la stabilità di strati di corrente bidimensionali inplasmi non-collisionali con un forte campo guida, sulla base di modelli girofluidi cheassumono ioni freddi. Questi modelli possono tenere conto di un’anisotropia di temperaturadi equilibrio e di un βe finito. Quest’ultimo è un parametro corrispondente alrapporto tra la pressione cinetica elettronica di equilibrio e la pressione magnetica.Deriviamo e analizziamo una relazione di dispersione per il tasso di crescita dei moditearing non-collisionali tenendo conto dell’anisotropia della temperatura di equilibriodegli elettroni. Le previsioni analitiche sono verificate mediante simulazioni numeriche,che mostrano un ottimo accordo quantitativo. Nel caso isotropico, tenendoconto degli effetti di βe finito, si osserva una stabilizzazione del tasso di crescita delmodo tearing quando diventano rilevanti gli effetti del raggio finito di Larmor deglielettroni. Nella fase non lineare si osservano fasi di decelerazione e fasi di accelerazione,simili a quanto avviene in presenza di effetti del raggio di Larmor finito ionico.Studiamo anche le condizioni di stabilità marginale degli strati di corrente secondaria,per lo sviluppo di plasmoidi, in plasmi senza collisioni. Nel regime isotropicocon βe → 0, analizziamo la geometria che caratterizza lo strato di corrente e identifichiamole condizioni in cui esso diventa instabile a causa di un’instabilità che generaplasmoidi. Il nostro studio mostra che i plasmoidi possono essere ottenuti, in questocontesto, da strati di corrente aventi un rapporto d’aspetto molto più piccolo rispettoal regime collisionale. Inoltre, studiamo la formazione di plasmoidi confrontando simulazionigirofluidi e girocinetiche. Ciò ha permesso di dimostrare che l’effetto di βe promuove l’instabilità che genera plasmoidi. Infine, si studia l’impatto della chiusuraapplicata ai momenti, eseguita durante la derivazione del modello girofluido, sulla distribuzionee conversione dell’energia durante la riconnessione
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Hörbe, Mario Robert [Verfasser], Julia [Gutachter] Tjus, and Garret [Gutachter] Cotter. "High-energy particle emission from plasmoids in jets of active galactic nuclei / Mario Robert Hörbe ; Gutachter: Julia Tjus, Garret Cotter ; Fakultät für Physik und Astronomie." Bochum : Ruhr-Universität Bochum, 2020. http://d-nb.info/1233484176/34.
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Lin, Ling. "Optical Manipulation Using Planar/Patterned Metallo-dielectric Multilayer Structures." Thesis, University of Canterbury. Electrical and Computer Engineering, 2008. http://hdl.handle.net/10092/1249.
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Tailoring surface plasmon (SP) resonances using metallic nanostructures for optical manipulation has been widely investigated in recent years; and there are many puzzles yet to be solved in this relatively new area. This thesis covers the study of the interaction of light with SP-supporting planar/patterned metallo-dielectric multilayer structures. Two separate, but closely related subjects were investigated using such structures, which are: SP-assisted optical transmission and optical metamaterials. The physical mechanisms of the SP-assisted transmission phenomenon were studied using planar/grating and planar/hole-array multilayer structures. Extraordinary light transmission has been demonstrated through experimental work and simulations for both arrangements; and the effects of different structural parameters on the transmission efficiencies of the structures were analyzed systematically. The interplays of the surface plasmon polaritons (SPPs) and localized surface plasmons (LSPs) in the extraordinary optical transmission (EOT) phenomenon were identified. The potential of the planar/hole-array multilayer structures as optical magnetic metamaterials was evaluated using two independent electromagnetic simulation techniques. The ability of such structures to produce strong magnetic resonances from infrared down to visible side of spectrum was revealed. The methods of tuning the magnetic response of the structures were suggested. A novel design of optical metamaterial based on high-order multipolar resonances in a single-layer plasmonic structure was also proposed. Numerical results from two different computation methods indicate that a simultaneously negative permittivity and permeability can be achieved in such a structure.
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Kurth, Martin L. "Plasmonic nanofocusing and guiding structures for nano-optical sensor technology." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/118670/1/Martin_Kurth_Thesis.pdf.
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This thesis investigated factors affecting the sensitivity of nano-optical sensors that could be used for the detection of trace amounts of explosives and environmental pollutants in air. By delivering air to regions of enhanced electric field produced by metallic nanostructures, as well as using structures that localise and guide light at nanoscale levels, detection limits can be reduced.
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Constant, Thomas J. "Optical excitation of surface plasmon polaritons on novel bigratings." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/9001.
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This thesis details original experimental investigations in to the interaction of light with the mobile electrons at the surface of metallic diffraction gratings. The gratings used in this work to support the resultant trapped surface waves (surface plasmon polaritons), may be divided into two classes: ‘crossed’ bigratings and ‘zigzag’ gratings. Crossed bigratings are composed of two diffraction gratings formed of periodic grooves in a metal surface, which are crossed at an angle relative to one another. While crossed bigratings have been studied previously, this work focuses on symmetries which have received comparatively little attention in the literature. The gratings explored in this work possesses two different underlying Bravais lattices: rectangular and oblique. Control over the surface plasmon polariton (SPP) dispersion on a rectangular bigrating is demonstrated by the deepening of one of the two constituent gratings. The resulting change in the diffraction efficiency of the surface waves leads to large SPP band-gaps in one direction across the grating, leaving the SPP propagation in the orthogonal direction largely unperturbed. This provides a mechanism to design surfaces that support highly anisotropic propagation of SPPs. SPPs on the oblique grating are found to mediate polarisation conversion of the incident light field. Additionally, the SPP band-gaps that form on such a surface are shown to not necessarily occur at the Brillouin Zone boundaries of this lattice, as the BZ boundary for an oblique lattice is not a continuous contour of high-symmetry points. The second class of diffraction grating investigated in this thesis is the new zigzag grating geometry. This grating is formed of sub-wavelength (non-diffracting) grooves that are ‘zigzagged’ along their length to provide a diffractive periodicity for visible frequency radiation. The excitation and propagation of SPPs on such gratings is investigated and found to be highly polarisation selective. The first type of zigzag grating investigated possesses a single mirror plane. SPP excitation to found to be dependant on which diffracted order of SPP is under polarised illumination. The formation of SPP band-gaps is also investigated, finding that the band-gap at the first Brillouin Zone boundary is forbidden by the grating’s symmetry. The final grating considered is a zigzag grating which possesses no mirror symmetry. Using this grating, it is demonstrated that any polarisation of incident light may resonantly drive the same SPP modes. SPP propagation on this grating is found to be forbidden in all directions for a range of frequencies, forming a full SPP band-gap.
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Loiselet, Ophelliam. "Synthèse et caractérisation d’agrégats bimétalliques pour la magnéto-plasmonique." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1033/document.
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Depuis plusieurs années les physiciens de la matière condensée s'intéressent aux propriétés optiques et magnétiques des nanoparticules métalliques. Deux propriétés restent largement étudiées : les résonances plasmon localisées et l'anisotropie magnétique à l'échelle nanométrique. Ces deux effets résultant de propriétés électroniques bien différentes sont habituellement rencontrés dans des nanosystèmes distincts. Depuis les années 2000 des études ont montré qu'il était possible de bénéficier de ces deux caractéristiques dans un seul et même système nanométrique. Dans cette thèse, nous nous intéresserons à la combinaison des propriétés magnétiques et plasmoniques dans des systèmes de taille inférieure à la dizaine de nanomètres: les agrégats bimétalliques de CoAg et de CoAu synthétisés par voie physique sous ultravide encapsulés en matrice (alumine et carbone). Nous nous intéresserons à la structure de ces agrégats bimétalliques de différentes stœchiométries et à l'effet de leur environnement à travers l'étude de leurs propriétés optiques, magnétiques et électroniques (par spectroscopie électronique par perte d'énergie (EELS) sur des particules individuelles). Nous montrerons l'effet de la matrice, carbone ou alumine, sur la structure des agrégats ainsi que sur leurs propriétés magnétiques (moment par agrégat, anisotropie). En optique nous verrons également l'importance de la stœchiométrie entre métal noble et cobalt sur les phénomènes d'amortissement et de décalage de résonance plasmon. Enfin nous montrerons la répartition spatiale des plasmons de surface sur des particules unique par des mesures de STEM-EELS<br>For several years condensed matter physicists have been interested in the optical and magnetic properties of metallic nanoparticles. Two properties remain largely studied: localized plasmon resonances and magnetic anisotropy at the nanoscale. These two effects resulting from very different electronic properties which are usually encountered in separate nanosystems. Since the 2000's, studies have shown that it is possible to benefit from these two characteristics in a single nanometric system. In this thesis, we will focus on the combination of magnetic and plasmonic properties in systems of size less than ten nanometers: bimetallic clusters of CoAg and CoAu synthesized physically under ultrahigh vacuum and embedded in a matrix (alumina and carbon). We will study the structure of these bimetallic clusters of different stoichiometries and the effect of their environment through the investigation of their optical, magnetic and electronic properties (by electron energy loss spectroscopy (EELS) on individual particles ). We will show the effect of the matrix, carbon or alumina, on the structure of the clusters as well as on their magnetic properties (moment by cluster, anisotropy). In optics we will also see the importance of stoichiometry between noble metal and cobalt on the phenomena of the damping and shifting of the plasmon resonance. Finally we will show the spatial distribution of surface plasmons on single particles by STEM-EELS measurements
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Nagaraj, Nagaraj. "Effects of Dissipation on Propagation of Surface Electromagnetic and Acoustic Waves." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc115126/.
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With the recent emergence of the field of metamaterials, the study of subwavelength propagation of plane waves and the dissipation of their energy either in the form of Joule losses in the case of electomagnetic waves or in the form of viscous dissipation in the case of acoustic waves in different interfaced media assumes great importance. with this motivation, I have worked on problems in two different areas, viz., plasmonics and surface acoustics. the first part (chapters 2 & 3) of the dissertation deals with the emerging field of plasmonics. Researchers have come up with various designs in an efort to fabricate efficient plasmonic waveguides capable of guiding plasmonic signals. However, the inherent dissipation in the form of Joule losses limits efficient usage of surface plasmon signal. a dielectric-metal-¬dielectric planar structure is one of the most practical plasmonic structures that can serve as an efficient waveguide to guide electromagnetic waves along the metal-dielectric boundary. I present here a theoretical study of propagation of surface plasmons along a symmetric dielectric-metal-dielectric structure and show how proper orientation of the optical axis of the anisotropic substrate enhances the propagation length. an equation for propagation length is derived in a wide range of frequencies. I also show how the frequency of coupled surface plasmons can be modulated by changing the thickness of the metal film. I propose a Kronig-Penny model for the plasmonic crystal, which in the long wavelength limit, may serve as a homogeneous dielectric substrate with high anisotropy which do not exist for natural optical crystals. in the second part (chapters 4 & 5) of the dissertation, I discuss an interesting effect of extraordinary absorption of acoustic energy due to resonant excitation of Rayleigh waves in a narrow water channel clad between two metal plates. Starting from the elastic properties of the metal plates, I derive a dispersion equation that gives resonant frequencies, which coincide with those observed in the experiment that was performed by Wave Phenomena Group at Polytechnic University of Valencia, Spain. Two eigenmodes with different polarizations and phase velocities are obtained from the dispersion equation. at certain critical aperture of the channel, an interesting cutoff effect, which is unusual for an acoustic wave, is observed for one of the eigenmodes with symmetric distribution of the pressure field. the theoretical prediction of the coupling and synchronization of Rayleigh waves strongly supports the experimentally measured shift of the resonant frequencies in the transmission spectra with channel aperture. the observed high level of absorption may find applications in designing metamaterial acoustic absorbers.
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Hettiarachchige, Chamanei Sandamali P. "The interaction of quantum dots with plasmons supported by metal waveguides." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/92278/1/Chamanei%20Sandamali_Hettiarachchige_Thesis.pdf.
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Plasmonics is a recently emerged technology that enables the compression of electromagnetic waves into miniscule metallic structures, thus enabling the focusing and routing of light on the nanoscale. Plasmonic waveguides can be used to miniaturise the size of integrated chip circuits while increasing the data transmission speed. Plasmonic waveguides are used to route the plasmons around a circuit and are a major focus of this thesis. Also, plasmons are highly sensitive to the surrounding dielectric environment. Using this property we have experimentally realised a refractive index sensor to detect refractive index change in solutions.
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ElKabbash, Mohamed. "ACTIVE PLASMONICS AND METAMATERIALS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1512659080056302.
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Vogel, Michael Werner. "Theoretical and numerical investigation of plasmon nanofocusing in metallic tapered rods and grooves." Thesis, Queensland University of Technology, 2009. https://eprints.qut.edu.au/29241/1/Michael_Vogel_Citation.pdf.
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Effective focusing of electromagnetic (EM) energy to nanoscale regions is one of the major challenges in nano-photonics and plasmonics. The strong localization of the optical energy into regions much smaller than allowed by the diffraction limit, also called nanofocusing, offers promising applications in nano-sensor technology, nanofabrication, near-field optics or spectroscopy. One of the most promising solutions to the problem of efficient nanofocusing is related to surface plasmon propagation in metallic structures. Metallic tapered rods, commonly used as probes in near field microscopy and spectroscopy, are of a particular interest. They can provide very strong EM field enhancement at the tip due to surface plasmons (SP’s) propagating towards the tip of the tapered metal rod. A large number of studies have been devoted to the manufacturing process of tapered rods or tapered fibers coated by a metal film. On the other hand, structures such as metallic V-grooves or metal wedges can also provide strong electric field enhancements but manufacturing of these structures is still a challenge. It has been shown, however, that the attainable electric field enhancement at the apex in the V-groove is higher than at the tip of a metal tapered rod when the dissipation level in the metal is strong. Metallic V-grooves also have very promising characteristics as plasmonic waveguides. This thesis will present a thorough theoretical and numerical investigation of nanofocusing during plasmon propagation along a metal tapered rod and into a metallic V-groove. Optimal structural parameters including optimal taper angle, taper length and shape of the taper are determined in order to achieve maximum field enhancement factors at the tip of the nanofocusing structure. An analytical investigation of plasmon nanofocusing by metal tapered rods is carried out by means of the geometric optics approximation (GOA), which is also called adiabatic nanofocusing. However, GOA is applicable only for analysing tapered structures with small taper angles and without considering a terminating tip structure in order to neglect reflections. Rigorous numerical methods are employed for analysing non-adiabatic nanofocusing, by tapered rod and V-grooves with larger taper angles and with a rounded tip. These structures cannot be studied by analytical methods due to the presence of reflected waves from the taper section, the tip and also from (artificial) computational boundaries. A new method is introduced to combine the advantages of GOA and rigorous numerical methods in order to reduce significantly the use of computational resources and yet achieve accurate results for the analysis of large tapered structures, within reasonable calculation time. Detailed comparison between GOA and rigorous numerical methods will be carried out in order to find the critical taper angle of the tapered structures at which GOA is still applicable. It will be demonstrated that optimal taper angles, at which maximum field enhancements occur, coincide with the critical angles, at which GOA is still applicable. It will be shown that the applicability of GOA can be substantially expanded to include structures which could be analysed previously by numerical methods only. The influence of the rounded tip, the taper angle and the role of dissipation onto the plasmon field distribution along the tapered rod and near the tip will be analysed analytically and numerically in detail. It will be demonstrated that electric field enhancement factors of up to ~ 2500 within nanoscale regions are predicted. These are sufficient, for instance, to detect single molecules using surface enhanced Raman spectroscopy (SERS) with the tip of a tapered rod, an approach also known as tip enhanced Raman spectroscopy or TERS. The results obtained in this project will be important for applications for which strong local field enhancement factors are crucial for the performance of devices such as near field microscopes or spectroscopy. The optimal design of nanofocusing structures, at which the delivery of electromagnetic energy to the nanometer region is most efficient, will lead to new applications in near field sensors, near field measuring technology, or generation of nanometer sized energy sources. This includes: applications in tip enhanced Raman spectroscopy (TERS); manipulation of nanoparticles and molecules; efficient coupling of optical energy into and out of plasmonic circuits; second harmonic generation in non-linear optics; or delivery of energy to quantum dots, for instance, for quantum computations.
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Vogel, Michael Werner. "Theoretical and numerical investigation of plasmon nanofocusing in metallic tapered rods and grooves." Queensland University of Technology, 2009. http://eprints.qut.edu.au/29241/.
Full textAbstract:
Effective focusing of electromagnetic (EM) energy to nanoscale regions is one of the major challenges in nano-photonics and plasmonics. The strong localization of the optical energy into regions much smaller than allowed by the diffraction limit, also called nanofocusing, offers promising applications in nano-sensor technology, nanofabrication, near-field optics or spectroscopy. One of the most promising solutions to the problem of efficient nanofocusing is related to surface plasmon propagation in metallic structures. Metallic tapered rods, commonly used as probes in near field microscopy and spectroscopy, are of a particular interest. They can provide very strong EM field enhancement at the tip due to surface plasmons (SP’s) propagating towards the tip of the tapered metal rod. A large number of studies have been devoted to the manufacturing process of tapered rods or tapered fibers coated by a metal film. On the other hand, structures such as metallic V-grooves or metal wedges can also provide strong electric field enhancements but manufacturing of these structures is still a challenge. It has been shown, however, that the attainable electric field enhancement at the apex in the V-groove is higher than at the tip of a metal tapered rod when the dissipation level in the metal is strong. Metallic V-grooves also have very promising characteristics as plasmonic waveguides. This thesis will present a thorough theoretical and numerical investigation of nanofocusing during plasmon propagation along a metal tapered rod and into a metallic V-groove. Optimal structural parameters including optimal taper angle, taper length and shape of the taper are determined in order to achieve maximum field enhancement factors at the tip of the nanofocusing structure. An analytical investigation of plasmon nanofocusing by metal tapered rods is carried out by means of the geometric optics approximation (GOA), which is also called adiabatic nanofocusing. However, GOA is applicable only for analysing tapered structures with small taper angles and without considering a terminating tip structure in order to neglect reflections. Rigorous numerical methods are employed for analysing non-adiabatic nanofocusing, by tapered rod and V-grooves with larger taper angles and with a rounded tip. These structures cannot be studied by analytical methods due to the presence of reflected waves from the taper section, the tip and also from (artificial) computational boundaries. A new method is introduced to combine the advantages of GOA and rigorous numerical methods in order to reduce significantly the use of computational resources and yet achieve accurate results for the analysis of large tapered structures, within reasonable calculation time. Detailed comparison between GOA and rigorous numerical methods will be carried out in order to find the critical taper angle of the tapered structures at which GOA is still applicable. It will be demonstrated that optimal taper angles, at which maximum field enhancements occur, coincide with the critical angles, at which GOA is still applicable. It will be shown that the applicability of GOA can be substantially expanded to include structures which could be analysed previously by numerical methods only. The influence of the rounded tip, the taper angle and the role of dissipation onto the plasmon field distribution along the tapered rod and near the tip will be analysed analytically and numerically in detail. It will be demonstrated that electric field enhancement factors of up to ~ 2500 within nanoscale regions are predicted. These are sufficient, for instance, to detect single molecules using surface enhanced Raman spectroscopy (SERS) with the tip of a tapered rod, an approach also known as tip enhanced Raman spectroscopy or TERS. The results obtained in this project will be important for applications for which strong local field enhancement factors are crucial for the performance of devices such as near field microscopes or spectroscopy. The optimal design of nanofocusing structures, at which the delivery of electromagnetic energy to the nanometer region is most efficient, will lead to new applications in near field sensors, near field measuring technology, or generation of nanometer sized energy sources. This includes: applications in tip enhanced Raman spectroscopy (TERS); manipulation of nanoparticles and molecules; efficient coupling of optical energy into and out of plasmonic circuits; second harmonic generation in non-linear optics; or delivery of energy to quantum dots, for instance, for quantum computations.
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Dubrovina, Natalia. "Metamaterials for photonic applications." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112088/document.
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L’objet de cette étude concerne l’exploration, à la fois sur le plan théorique et expérimental, de la possibilité d’utilisation des métamatériaux pour des applications dans le domaine de la photonique aux longueurs d’onde télécoms (λ=1.5µm). L’un des principaux objectifs adressés dans le cadre de la thèse est de réaliser l’ingénierie de l’indice effectif en utilisant des résonances des plasmons de surface localisés des métamatériaux métallo-diélectriques. Deux cas particulièrement importants du point de vue de la réalisation technologique sont considérés :• Propagation en espace libre quand une onde lumineuse sous incidence normale ou oblique interagit avec une surface diélectrique recouverte d’une monocouche de métamatériaux.• Propagation dans une configuration guide d’onde avec une monocouche de métamatériaux à la surface d’un guide d’onde en Silicium.Les résultats des modélisations et des mesures expérimentales montrent que les propriétés optiques d’une mono-couche de métamatériau peuvent être décrites par celle d’une couche homogène avec un certain indice effectif. L’épaisseur de cette couche est égale à celle des motifs métalliques, à condition qu’elle soit inférieure à quelques dizaines de nm. Pour des faibles facteurs de remplissage en surface, l’indice de réfraction d’une telle couche suit l’approximation de Maxwell-Garnett. Cet indice effectif ne dépend pas de l’angle d’incidence ni de l’orientation de la polarisation de la lumière (perpendiculaire ou dans le plan d’incidence). Au voisinage de la fréquence de résonance pour un facteur de remplissage de métamatériau de 20% en surface on obtient un indice de réfraction très élevé : neff=10. Cet indice de réfraction est plusieurs fois supérieur à celui qu’on trouve dans des matériaux naturels. L’adaptation de cette approche à configuration guidée à utiliser une structure hybride composée d’une couche de métamatériau à la surface d’un guide d’onde en Silicium. Les travaux réalisés ont permis de démontrer la possibilité d’effectuer l’ingénierie de l’indice effectif et de contrôler le niveau des pertes d’un tel guide d’onde hybride en utilisant des métamatériau métallo-diélectriques à base des fils d’Au de 200X50X50nm. Le contraste d’indice au voisinage de la ligne de la résonance donné par des modélisations et confirmé expérimentalement est de ±1.5, soit plus que ce que l’on peut obtenir avec un guide Silicium gravé. Ce résultat représente une première démonstration sur le plan international de fonctionnement des métamatériaux en configuration guidée.De plus, en contrôlant l’orientation des motifs de métamatériaux, on peut réaliser un indice anisotrope. Les résultats obtenus ouvrent des perspectives très prometteuses pour la réalisation de dispositifs en optique guidée utilisant les transformations d’espace<br>The subject of the PhD thesis deals with metamaterials for photonic applications. The main objective is to investigate the potential of metallic metamaterials for building optical functions at NIR optical frequencies. A significant part of the work is focused on the engineering of the metamaterials effective index associated with localized plasmon resonances. Two configurations of particular importance for fabrication technology are considered:• Free space light propagation, with the incident electromagnetic wave interacting with single metafilms at either normal or oblique incidence. • Guided wave configuration, with single metamaterial layer placed on top of dielectric waveguide.For the free space configuration, the validity of the effective medium approach was investigated both numerically and experimentally with the example of metamaterials composed of either gold cut wires or split ring resonators and continuous wires on silicon substrate. On the basis of these examples it was shown that the metafilm behavior is indeed analogous to that of a homogeneous layer. The thickness of this layer is that of the deposited metal. The validity of this conclusion was verified with respect to a number of criteria consistent with the Maxwell-Garnett approximation. It was shown in particular that near the resonance frequency the effective index of the metafilm layer can reach very high values neff=10 that cannot be attained with natural materials.The effective medium approach developed for a single metamaterial layer in free space configuration was further extended to a guided wave configuration. The objective is to achieve an efficient control over the flow of light in the waveguide using effective index variations induced by metamatarial resonances. The possibility of achieving a significant effective index variation with a silicon slab waveguide covered by 200X50X50nm cut wires was investigated by numerical modeling and confirmed by experimental results. The magnitude of local index variation in the vicinity of the resonance frequency deduced from experimental data is as high as ±1.5. The possibility for controlling the local effective index at the nanoscale can be used in transformation optics applications. The hybrid metamaterial guided wave configuration may become a promising alternative to the bulk multi-layers metamaterial structures in the near infrared domain
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Sönnichsen, Carsten. "Plasmons in metal nanostructures." [S.l.] : [s.n.], 2001. http://edoc.ub.uni-muenchen.de/archive/00002367.
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Sönnichsen, Carsten. "Plasmons in metal nanostructures." Diss., lmu, 2001. http://nbn-resolving.de/urn:nbn:de:bvb:19-23678.
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Kadic, Muamer. "Metamaterials for surface plasmons." Thesis, Aix-Marseille 3, 2011. http://www.theses.fr/2011AIX30026.
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Le travail présenté dans cette thèse comporte différents attrayant sujetsde l'optique comme les métamatériaux, l’optique transformationnelle, lescristaux photoniques, la réfraction négative et les interactions thermoplasmoniques.Nous avons développé plusieurs métamatériaux pour les plasmons desurface basés sur l'optique de transformation. Tout d'abord, nous avonsdémontré théoriquement, numériquement et expérimentalement certainsdispositifs mettant en scène le phénomène d’invisibilité.Deuxièmement, nous avons démontré la réfraction négative des plasmonsde surface en utilisant le concept d'espace de pliage (space folding) pourdes lentilles plates et anisotropes et enfin avec seulement desmétamatériaux diélectriques. Additionnellement, nous avons démontréqu’un damier structuré de films d'or peut exhiber une transmission extraordinairesur toute la gamme de fréquences visible.Enfin, nous avons étudié un problème multiphysique en mixant l'optiqueet thermique et leurs effets induits. Nous avons pu montrer que joueravec l'amplitude d'une onde électromagnétique ou une impulsion, peutinduire un gradient de température et le contrôle parfait d’un tel dispositifthermo-plasmonique<br>The work which has been presented in this thesis includes differentappealing subjects of optics such as metamaterials, transformationaloptics, photonic crystals, negative refraction and thermo-plasmonicinteractions. In this manuscript we have developed several metamaterialsfor Surface Plasmon Polaritons based on the transformational optics.Firstly we have demonstrated theoretically, numerically andexperimentally some SPP cloaking devices. Secondly, we havedemonstrated SPP negative refraction using the concept of space foldingthen with some dielectric metamaterial, flat and anisotropic SPP lenses.Additionaly we have demonstrated that subwavelength checkerboardstructured thick gold films have demonstrated an extra-ordinarytransmission over the visble range of frequencies.Finally, we have investigated a general multiphysics problem to mix opticsand thermally induced effects. We have been able to show that playingwith the amplitude of an electromagnetic wave or a pulse, we can inducea gradient of temperature and control heat of a plasmonic device
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Burnett, Mathew T. "Microspectroscopy of localised plasmons." Thesis, University of Bath, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516954.
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Working with nanoscale optics requires methods and equipment designed for the purpose. This thesis describes the development of techniques and a system for performing highly localised spectroscopy. The system consists of a nanonics multiview 2000 scanning near-field optical microscope, a grating spectrometer and a photonic crystal fibre supercontinuum light source. Discussion of the microscope includes its modes of operation and development of software to collect and analyse data. In order to demonstrate the setup, an example of localised spectroscopy is presented in the form of an investigation of hollow core photonic crystal fibre. Taking spectra of the components of the cladding of these fibres makes it possible to investigate the origins of bandgap guidance. A core focus of nanoscale optics is the interaction of light with metal structures. This field is called plasmonics. Fabrication of structures is presented and requires special facilities and processes. These processes are both time consuming and expensive, both factors that emphasise the need for prior modelling. Forward difference time domain modelling of a proposed structure comprising of a concentrically arranged ring and disk is explored using home written code and a commercial package called CST Microwave Studio. The investigation of this concentric design through modelling shows a very highly localised field enhancement which can be engineered to have a narrow spectral resonance in the near infrared. The interaction of the two components which govern this resonance is explained using a theory called plasmon hybridization. Once the optical behaviour of small metal objects is understood they can be used in other ways. An example of this is shown in Porous Silicon. As a material it provides an excellent template for formation of metal nano-particles. Embedded in a high surface area network of silicon these particles can be used as very effcient catalysts.
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Turek, Vladimir. "Plasmonics at liquid-liquid interfaces." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/38445.
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The PhD has studied gold nanoparticles (NPs) at the liquid-liquid interface (LLI). Some of the key aspects of the work are listed below. • Centrifugation as a novel and efficient method for adsorbing a controlled number of NPs to the LLI. • Controlled and tuneable 2D interparticle separation at the LLI as evidenced by the plasmon ruler. • Reversible adsorption of 16 nm gold nanoparticles at the water-DCE interface. • Centrifugation as a novel method to form an ultra-concentrated NP aqueous phase. • Controlled and tuneable 3D inter-particle separation in water by ultra-concentration. • The ultra-concentrated NP solution has some 'record-breaking' physical properties - e.g. densities in excess of 4.5 gcm-3; optical densities in excess of 70,000; and active surface areas of in excess of 70 m2/mL. • Ultra-concentration is also demonstrated as an efficient purification and NP size-separation technique with efficiencies in excess of 99.9% and 99.5%, respectively. • Close-packed NPs at the LLI are also demonstrated to be an efficient sensing platform through surface enhanced Raman spectroscopy. • The platform benefits from: fmole detection limits; extremely facile, quick and cheap assembly; applicability to a wide range of target analytes; both hydrophilic and hydrophobic detection capabilities simultaneously. • Through evaporation of the organic phase, the platform is also demonstrated to be able to identify and estimate concentrations of airborne analytes. • Finally, 1,8-diaminonaphthalene and its analogues are demonstrated to be extremely efficient mercury reporters when combined with SERS at the LLI. • A dramatic increase in SERS intensity is observed in the presence of mercury - though the exact reason for such an increase is still under investigation, some potential mechanisms are provided. • As with other analytes, NPs at the liquid-air interface demonstrate airborne mercury detection capabilities and this is demonstrated for the first time using SERS.
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Kaube, Benjamin. "Plasmonics : from electrons to devices." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/58997.
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From molecular sensors to perfect lenses, plasmonic devices promise a wealth of breakthrough applications by coupling light to oscillations of the electron plasma. In order to harness the full technological potential of plasmonics, coherent plasma excitations must be sustained over many cycles. On the scale of practical devices, optical properties of media are characterised by the mascroscopic dielectric function. This quantity can be determined from first principles in terms of transitions between electronic states. Understanding of losses within plasmonic systems must thus be built up from electrons to devices -- the approach taken in this thesis. Optical losses are explored with application to prototypical plasmonic systems, noble metals copper, silver and gold. Density functional theory with quasiparticle self-consistent GW (QSGW) corrections are employed in order to build up an accurate description of the electronic states. Interband dielectric functions are consequently obtained within the linear response formalism, finding good agreement with experimental literature. Electron interactions with lattice vibrations are found to be an essential feature in describing optical losses at low energies (also known as Drude losses). Electron-phonon interactions are included by two approaches: many body perturbation theory via the phonon contribution to the self energy and the semi-classical Williams Lax averages over nuclear displacements. The latter approach was used to determine the temperature dependence of silver optical spectra and constants from first principles, achieving agreement with experiment. Lastly, first principles calculations of silver nanodots are presented.
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Peng, Cheng S. M. Massachusetts Institute of Technology. "Towards infrared plasmonics in graphene." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/101585.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2015.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 59-64).<br>Graphene plasmons have recently been proposed as an alternative to noble-metal plasmons in the field of photonics, due to its extremely tight light confinement, relatively long-lived collective oscillation, and high tunability via electrostatic gating. Successful support and tuning of graphene plasmonic modes rely on controllable doping of graphene to high carrier densities in nanometer-scale structures. In this thesis, an experimental approach to generating nanoscale spatial carrier density modulation of graphene using electrolyte gates and crosslinked-PMMA screen is proposed and investigated. The increased optical absorption in the infrared region due to plasmon resonances induced by the proposed scheme is numerically studied. We then present the fabrication technique of the proposed scheme for various nanostructure geometries. Finally, we provide an outlook of future studies of graphene plasmonics, including plasmon excitation with solid-state cavity quantum electrodynamics (QED).<br>by Cheng Peng.<br>S.M.
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Khlopin, Dmitry. "Aluminum plasmonics for optical applications." Thesis, Troyes, 2017. http://www.theses.fr/2017TROY0034.
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La plasmonique repose sur les champs électromagnétiques intenses et confinés apparaissant à résonance autour de nanostructures métalliques. Parmi ces métaux, l'aluminium soutient une gamme variée de résonances plasmoniques de l'UV jusqu’à l'IR. En raison des pertes élevées dans le visible, une amélioration est nécessaire pour concurrencer les métaux nobles. Une stratégie pour augmenter la qualité des résonances est d’utiliser un couplage diffractif au sein d’un réseau périodique. Nous montrons expérimentalement et numériquement une amélioration d’un facteur 7 du facteur de qualité par rapport à la particule isolée. Ensuite, nous couplons des nanoparticules d’Al avec un semiconducteur à grand gap pour exalter son émission. Un réseau de particules d’Al a été déposé sur une couche épitaxiale d'oxyde de zinc. Les résultats montrent une amélioration de 1,5 fois par rapport au ZnO natif. Pour améliorer cet effet et couvrir plus efficacement la surface, nous avons ensuite utilisé une géométrie fractale, inspirée de la technologie radio. Les structures ont été conçues via des simulations FDTD, puis elles ont été fabriquées à l’aide d’un procédé de lithographie électronique adapté. Finalement, nous proposons le concept d’une fractale chirale. Grâce à la géométrie complexe des fractales, il est possible de pousser l’activité optique des structures plasmoniques vers la partie UV du spectre. Des échantillons ont été conçus et fabriqués, prouvant l’existence de dichroïsme circulaire dans les fractales<br>Plasmonics is based on the intense and confined electromagnetic fields appearing near metallic nanostructures illuminated at frequencies near their surface plasmon resonances. Among the different metals, aluminum sustains a broad range of plasmonic resonances from deep UV to near IR. Due to high losses in the visible, aluminum plasmonic structures require an improvement to compete with noble metals. First, we present a strategy to increase the resonance quality based on diffractive coupling in periodic arrays. This approach, studied with simulations and experimental methods, provides a change of quality factor of resonance up to 7 times in comparison with an isolated particle. Then, we couple aluminum nanostructures with a wide band gap semiconductor to enhance its emission. Periodic arrays of Al nanoparticles were fabricated onto a ZnO epitaxial layer. Results show an enhancement of emission of 1.5 times in comparison with pristine ZnO. To increase the effect and get a more efficient surface coverage, we then used a fractal geometry inspired from radiowave technology. FDTD simulations were performed to design an effective geometry and the structures were fabricated with an adapted electron beam lithography process. Finally, we propose a concept of chiral fractals. Using the complex geometry of fractals, it is possible to push optical chirality of plasmonic structures toward the UV part of the spectrum. Samples were fabricated and the existence of circular dichroism in fractal structures was proven
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Ansell, Daniel. "Graphene for enhanced metal plasmonics." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/graphene-for-enhanced-metal-plasmonics(7bb0ffb1-f46f-498e-bb88-9626021f6f58).html.
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The experimental work undertook in this thesis looks to integrate technologies developed by the graphene and plasmonics communities, respectively, for the purpose of producing devices of enhanced qualities to those of similar utility that have previously been produced. Furthermore, where possible, we look to offer disruptive innovation, by utilising coupled properties that may offer unique possibilities for applications. A hybrid graphene-plasmonic waveguide modulator is fabricated and shown to operate successfully at a standard telecommunications frequency. Different plasmonic-waveguide designs — the basis for the modulator — were produced to probe the coupling between graphene and the surface plasmon-polariton modes. A mode excitable at the edge of the waveguide was found to offer the best modulation, with a modulation depth of over 0.03 dB μm^−1, induced by a moderate gating voltage of about 10 V. Topologically-protected darkness (zero reflection) was produced by particular engineering of a plasmonic metamaterial. This allowed generation of a singularity in the ellipsometric phase (a particular parameter of light), allowing for measurements of mass sensitivity of ∼10 fg mm^−2, with the possibility of improving this to ∼100 ag mm^−2. Graphene was employed in a novel metrology tool to measure the sensitivity of this device. With respect to fundamental losses in plasmonics, one could find either a new plasmonic material or look to improve an existing one. Work was undertook with respect to this latter option by attempting to preserve the otherwise excellent plasmonic properties of copper and silver through a protective barrier of graphene. This was achieved and illustrated through ellipsometric measurements taken over various timescales. Fabrication of a dielectric loaded waveguide on graphene-protected copper was then carried out, with operation of the waveguide proving successful, possibly opening the field of active graphene-protected metal plasmonics.
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Luo, Yu. "Transformation optics applied to plasmonics." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/10521.
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Lately, transformation optics (TO) has driven the development of metamaterial science, providing a direct link between a desired electromagnetic phenomenon and the material response required for its occurrence. However, this powerful framework is not restricted to the metamaterial design, and it has recently been exploited to study surface plasmon assisted phenomena. In this thesis, we mainly focus on the general strategy based on TO to design and study analytically plasmonic devices capable of efficiently harvesting light over a broadband spectrum and achieving considerable field confinement and enhancement. Using TO, we show that a finite nanoparticle with sharp geometrical features can behave like an infinite plasmonic system, thereby allowing simultaneously a broadband interaction with the incoming light as well as a spectacular nanofocusing of its energy. Various plasmonic structures are designed and studied, such as 2D crescents, groove/wedge like nanostructures, overlapping nanowires, and rough metal surfaces. Comprehensive discussions are also provided on practical issues of this problem. First, we discuss how the edge rounding at the sharp boundary affects the local field enhancement as well as the energy and bandwidth of each plasmonic resonance. In particular, the necessary conditions for achieving broadband light harvesting with blunt structures are highlighted. The TO approach is then applied to study the interaction between plasmonic nanoparticles. We demonstrate that the energy and spectral shape of the localized surface plasmon resonances can be precisely controlled by tuning the separation between the nanoparticles. Finally, we consider the extension of the TO framework to 3D geometries, and show that the 3D structure is more robust to radiative loss than its 2D counterpart. The physical insights into sharp and blunt plasmonic nanostructures presented in this thesis may be of great interest for the design of broadband light-harvesting devices, invisible and non-invasive biosensors, and slowing-light devices.
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LIN, LYUYE. "Plasmonics in Metal Insulator Cavities." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1071822.
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Subwavelength multilayer metal-insulator nanostructures with tuneable resonances have been widely used for various applications in optoelectronics and photonics, due to their unique dispersion relation of the dielectric permittivity. In this thesis, we firstly studied the optical properties and the resonance modes of the metal/insulator/metal (MIM) metamaterial system by spectroscopic ellipsometry and COMSOL Multiphysics calculations based on finite element methods. Our calculation results show that MIM systems with vertical or lateral gratings can both support the multiple cavity modes that form the epsilon-near-zero (ENZ) resonance with an effective dielectric constant close to zero. Their large local density states are beneficial to the Purcell effect enhancement of the spontaneous emission. Moreover, the low-energy multi-cavity modes can be adjusted in the visible range via tuning the insulator thickness. The difference is that the MIM system with lateral grating leads to uncoupled multiple ENZ resonance, while the vertical grating MIM structure owns strongly coupled modes which form ENZ bands.
To demonstrate the usefulness of the emission enhancement of MIM structures in practical applications, multilayer metal-insulator nanostructures are adopted to improve the spontaneous emission of the emitter. Herein, we explored the effects of interface modifications on the overall performance in perovskite LEDs. Firstly, we designed and optimized the flat perovskite LED (PeLED) through systematic analysis of the power loss channels based on the optical mode. All the theoretical analysis is carried out through finite element simulations. Under the assumption of efficient photon generation in the emitting layer with an internal quantum yield of 0.9, the effect of the dipole orientation is analyzed and then thickness of the charge injection and emitter layer was optimized. Finally, we tuned the transparent electrode thickness to get the maximum value of the external quantum efficiency. Moreover, we further studied the influence of interface modifications happening at the electron-transport interface on the whole performance of perovskite-based flat PeLEDs. Particularly, we explored the integrating of photonic structure, while keeping the optical property of the emitting material. Interesting, our calculations reveal that the specially designed nanopatterning can promote to improve the Purcell factor and the outcoupling efficiency, thereby enhance the external quantum efficiency, related to the nanopattern-free PeLED configuration. In particular, an average enhancement around 100% for the external quantum efficiency was achieved, and thus improving the radiative emission of the PeLED devices. These findings indicated that using morphological patterning to enhance LED performance is realistic method, similar to other light emission technologies.
Finally, a nanoscale optical pressure/temperature nano sensor based on gap-plasmonic nanostructure, composing of the MIM nanopillar arrays covered by a metallic film, is proposed. The gap plasmon frequency is highly sensitive to the distance of the pillars to the Ag film, which allows optical sensing of pressure/ambient temperature/ refractive-index by variation in the colour of the device.
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Édes, Zoltán. "Fotoluminiscence zesílená plazmonovými polaritony." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230270.
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Diplomová práce se zabývá fotoluminiscencí polovodičových materiálů zesílené plazmonovými polaritony. Je popsána základní teorie interakce mezi lokalizovanými povrchovými plazmonovými polaritony a fotoluminiscenčními látkami. Dva mechanismy, které mohou vést k fotoluminiscenci zesílené plazmonovými polaritony jsou diskutovány. Následně je popsán návrh aparatury pro měření fotoluminiscence a způsob její realizace. Funkčnost aparatury je ověřena měřením fotoluminiscenčních spekter objemového GaN, nanokrystalického Si a CdTe kvantových teček. Nakonec je zkoumána metoda přípravy vzorků sestávajících z kovových nanokuliček a fotoluminiscenčně aktívních CdTe kvantových teček.
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DELANNEE, CECILE. "Contribution a l'etude des plasmoides de la couronne solaire." Paris 6, 1997. http://www.theses.fr/1997PA066296.
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La couronne solaire est le lieu de phenomenes encore inexpliques. Des nuages de plasma se deplacent en son sein. Ces nuages sont aussi appeles plasmoides. Dans mon travail de these, j'ai analyse trois observations de plasmoides. Chacune presente des resultats originaux. Les plasmoides sont plus denses, plus froids et plus magnetises que la couronne ambiante. Leur vitesses varient de 20 km s#-#1 a 150 km s#-#1. Leur dynamique est tres particuliere. Pour l'expliquer, j'ai determine les forces agissant sur ces nuages. L'interaction des nuages avec la couronne est non collisionnelle et est dominee par le champ magnetique. La mhd ideale est applicable. Le champ magnetique interne au plasmoide est modelise par celui cree par un dipole situe en son centre de masse. J'ai calcule le mouvement de ce dipole dans le champ magnetique coronal. Ce modele permet d'expliquer en partie les resultats obtenus lors des observations. Ce travail montre que les plasmoides sont frequemment emis dans la couronne et qu'il peuvent participer a l'initiation du vent solaire.
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Jory, Michael John. "Optical sensing with surface plasmons." Thesis, University of Exeter, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240308.
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Ager, C. D. "Plasmons in microstructured semiconductor 2DEGs." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385904.
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Jain, Prashant K. "Plasmons in assembled metal nanostructures." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/28207.
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Thesis (M. S.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2008.<br>Committee Chair: El-Sayed, Mostafa A.; Committee Member: Lyon, L. Andrew; Committee Member: Sherrill, C. David; Committee Member: Wang, Zhong Lin; Committee Member: Whetten, Robert L.
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Héron, Sébastien. "Nanostructures pour l'exaltation d'effets non linéaires." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX082/document.
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Les sources infrarouges basées sur des effets d'optique du second ordre constituent de très bons outils de spectrométrie des polluants présents dans l'atmosphère, grâce notamment à leur grande accordabilité spectrale. Ils demandent toutefois une forte puissance lumineuse incidente et une grande quantité de matériau non linéaire pour être efficaces. On peut les rendre très compactes en réalisant la conversion de fréquence à l'aide de nanostructures plasmoniques contenant des inclusions diélectriques présentant une susceptibilité du deuxième ordre non nulle. La lumière y est très fortement concentrée à la résonance augmentant fortement la quantité de polarisation non linéaire produite, afin d'y exalter les effets d'optique non linéaire.Ce travail s'attaque d'abord à la conception de nano-résonateurs grâce au développement d'un outil de simulation d’empilements nanostructurés selon une dimension. Trois architectures sont étudiées : les nanorésonateurs de type sillon, les nanorésonateurs de Helmholtz et les guides d'ondes à résonances de modes guidés. Dans chaque cas, le dimensionnement passe par la détermination de géométries bi- voire tri-résonantes pour la réalisation d'accord de modes en génération de second harmonique ou de différence de fréquences.La fabrication en salle blanche des résonateurs sillons et guides d'ondes est ensuite exposée, suite à un important travail de développement technologique, qui a permis l’obtention d’échantillons de très bonne qualité<br>Infrared sources based on second order effects are interesting tools for atmospheric pollutants spectrometry thanks to their wide tunability. Such effects nevertheless demand strong incident powers or massive non linear crystals to be efficient. A new way to reduce their size consists in realizing frequency conversion with the help of plasmonic nanostructures containing dielectric inclusions showing a non zero second order susceptibility. Light is greatly harvested and concentrated at resonance leading to the creation of a great quantity of non linear polarization, so as to further enhance non linear optics effects.This work begins with a study of nanoresonators through developing a simulation tool for one dimensional nanostructured multilayered structures. Three architectures are retained : slit nanoresonators, optical Helmholtz nanoresonators and waveguides based on guided mode resonances. In every case, the conception focuses on the finding of bi- and even of tri-resonant geometries to achieve mode matching for second harmonic of difference frequency generation.Clean room fabrication is then detailed step by step following the important works that have permitted the fabrication of samples showing a very good quality
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Lei, Dang-Yuan. "Superfocusing, biosensing and modulation in plasmonics." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/9046.
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Plasmonics could bridge the gap between photonics and electronics at the nanoscale, by allowing the realization of surface-plasmon-based circuits and plasmonic chips in the future. To build up such devices, elementary components are required, such as a passive plasmonic lens to focus free-space light to nanometre area and an active plasmonic modulator or switch to control an optical response with an external signal (optical, thermal or electrical). This thesis partially focuses on designing novel passive and active plasmonic devices, with a specific emphasis on the understanding of the physical principles lying behind these nanoscale optical phenomena. Three passive plasmonic devices, designed by conformal transformation optics, are numerically studied, including nanocrescents, kissing and overlapping nanowire dimers. Contrary to conventional metal nanoparticles with just a few resonances, these devices with structural singularities are able to harvest light over a broadband spectrum and focus it into well-defined positions, with potential applications in high efficiency solar cells and nanowire-based photodetectors and nanolasers. Moreover, thermo-optical and electrooptical modulation of plasmon resonances are realized in metallic nanostructures integrated with either a temperature-controlled phase transition material (vanadium dioxide, VO2), or ferroelectric thin films. Taking advantage of the high sensitivity of particle plasmon resonances to the change of its surrounding environment, we develop a plasmon resonance nanospectroscopy technique to study the effects of sizes and defects in the metal-insulator phase transition of VO2 at the single-particle level, and even single-domain level. Finally, we propose and examine the use of two-dimensional metallic nanohole arrays as a refractive index sensing platform for future label-free biosensors with good surface sensitivity and high-throughput detection ability. The designed plasmonic devices have great potential implications for constructing nextgeneration optical computers and chip-scale biosensors. The developed plasmon resonance nanospectroscopy has the potential to probe the interfacial or domain boundary scattering in polycrystalline and epitaxial thin films.
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Iyer, Srinivasan. "Effects of surface plasmons in subwavelength metallic structures." Doctoral thesis, KTH, Optik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103613.
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The study of optical phenomena related to the strong electromagnetic response of noble metals (silver (Ag) and gold (Au) being most popular) over the last couple of decades has led to the emergence of a fast growing research area called plasmonics named after 'surface plasmons' which are electron density waves that propagate along the interface of a metal and a dielectric medium. Surface plasmons are formed by the coupling of light to the electrons on the metal surface subject to the fulfillment of certain physical conditions and they are bound to the metal surface. Depending on whether the metallic medium is a continuous film or a structure having dimensions less than or comparable to the wavelength of the exciting light, propagating or localized surface plasmons can be excited. The structure can be either a hole or an arbitrary pattern in a metal film, or a metallic particle. An array of subwavelength structures can behave as an effective homogeneous medium to incident light and this is the basis of a new class of media known as metamaterials. Metallic metamaterials enable one to engineer the electromagnetic response to incident light and provide unconventional optical properties like negative refractive index as one prominent example. Metamaterials exhibiting negative index (also called negative index materials (NIMs)) open the door for super resolution imaging and development of invisibility cloaks. However, the only problem affecting the utilization of plasmonic media to their fullest potential is the intrinsic loss of the metal, and it becomes a major issue especially at visible-near infrared (NIR) frequencies. The frequency of the surface plasmon is the same as that of the exciting light but its wavelength could be as short as that of X-rays. This property allows light of a given optical frequency to be conned into very small volumes via subwave lengthmetallic structures, that can be used to develop ecient sensors, solar cells, antennas and ultrasensitive molecular detectors to name a few applications. Also, interaction of surface plasmons excited in two or more metallic subwavelength structures in close proximity inuences the far-eld optical properties of the overall coupled system. Some eects of plasmonic interaction in certain coupled particles include polarization conversion, optical activity and transmission spectra mimicking electromagnetically-induced transparency (EIT) as observed in gas based atomicsy stems. In this thesis, we mainly focus on the optical properties of square arrays of certain plasmonic structures popularly researched in the last decade. The structures considered are as follows: (1) subwavelength holes of a composite hole-shape providing superior near-eld enhancement such as two intersecting circles (called' double hole') in an optically thick Au/Ag lm, (2) double layer shnets, (3) subwavelength U-shaped particles and (4) rectangular bars. The entire work is based on electromagnetic simulations using time and frequency domain methods. Au/Ag lms with periodic subwavelength holes provide extraordinarily high transmission of light at certain wavelengths much larger than the dimension of the perforations or holes. The spectral positions of the maxima depend on the shape of the hole and the intra-hole medium, thereby making such lms function as a refractive index sensor in the transmission mode. The sensing performance of the double-hole geometry is analyzed in detail and compared to rectangular holes. Fishnet metamaterials are highly preferred when it comes to constructing a NIM at optical frequencies. A shnet design that theoretically oers a negative refractive index with least losses at telecommunication wavelengths (1.4 1.5 microns) is presented. U-shaped subwavelength metallic particles, in particular single-slit split-ring resonators (SSRRs), provide a large negative response to the magnetic eld of light at a specic resonance frequency. The spectral positions of the structural resonances of the U-shaped particle can be found from its array far field transmission spectrum at normal incidence. An effort is made to clarify our understanding of these resonances with the help of localized surface plasmon modes excited in the overall particle. From an application point of view, it is found that a planar square array of SSRRs eectively functions as an optical half-wave waveplate at the main resonance frequency by creating a polarization in transmission that is orthogonal to that of incident light. A similar waveplate eect can be obtained purely by exploiting the near-eld interaction of dierently oriented neighbouring SSRRs. The physical reasons behind polarization conversion in dierent SSRR-array systems are discussed. A rectangular metallic bar having its dipolar resonance in the visible-NIR is called a nanoantenna, owing to its physical length in the order of nanometers. The excitation of localized surface plasmons, metal dispersion and the geometry of the rectangular nanoantenna make an analytical estimation of the physical length of the antenna from the desired dipolar resonance dicult. A practical map of simulated resonance values corresponding to a variation in geometrical parameters of Au bar is presented. A square array of a coupled plasmonic system comprising of three nanoantennas provides a net transmission response that mimicks the EIT effect. The high transmission spectral window possesses a peculiar dispersion profile that enables light with frequencies in that region to be slowed down. Two popular designs of such plasmonic EIT systems are numerically characterized and compared.<br><p>QC 20121017</p>
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Hugall, James T. "On the nature of SERS from plasmonic nanostructures." Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/267496.
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The nature of surface-enhanced Raman scattering (SERS) on nanostructured surfaces is explored using both inorganic and organic-based systems and a variety of environmental perturbation mechanisms. Experimental optical characterisation systems are developed and existing systems extended to facilitate this exploration. SERS of inorganic semiconducting quantum dots (QDs) is observed for the first time, paving the way for their use as spatially well-defined SERS markers. Tuning of the Raman excitation wavelength allows comparison between resonance and nonresonance QD SERS and identifies enhancement due to the plasmonic nanostructure. A gentle mechano-chemical process (carbon dioxide snow jet) is used to rearrange adsorbed organic thiol monolayers on a gold plasmonic nanostructure. The necessity of nanoscale roughness to the large SERS enhancement on pit-like plasmonic nanostructures is shown and demonstrates a new method to boost SERS signals (> 500 %) on plasmonic nanostructures. A multiplexed time-varied exposure technique is developed to track this molecular movement over time and highlights the different origins of the SERS peak and its accompanying background continuum. Using low-temperature cryogenics (down to 10 K) the SERS peak and background continuum intensity are shown to increase as the plasmonic metal damping reduces with temperature. Temperature dependent measurements of QD (resonance) SERS are shown to have strong wavelength dependence due to the excitonic transitions in QDs. Changes to the QD fluorescence at low temperature allows striking comparison between the Raman and fluorescence processes. The role of charge transfer and electromagnetic enhancement in the SERS intensity of p-aminothiophenol (pATP) is investigated on nanostructured plasmonic surfaces coupled to metallic nanoparticles. The results support the importance of charge transfer effects to the SERS of pATP, and highlight the difference between those of electromagnetic origin. Addition of nanoparticles to the nanostructured surface was seen to enhance SERS signals by up to 100×.
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Otomalo, Tadele. "Ultrafast optical response of complex plasmonic nanoparticles." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC102.
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Les propriétés remarquables associées à la résonance plasmon localisée (LSPR) dans les nanoparticules (NP) de métaux nobles font de la plasmonique un sujet aux applications multiples. Lorsque les NP sont éclairées par des impulsions laser ultracourtes, une dynamique rapide d'échanges d'énergie conduit à la variation ultrarapide de leurs propriétés optiques, accompagnée d’autres effets comme la photoluminescence, l’échauffement hyperlocalisé, la photoémission électronique, la production de radicaux libres, la nano-cavitation. La conception de nanostructures hybrides complexes permet d'adapter les propriétés plasmoniques pour optimiser les applications. Nous avons étudié certaines nanostructures hybrides par spectroscopie d'absorption pompe-sonde large bande et une modélisation dédiée : fibres de silice décorées de NP d’or, NP cœurs-coquilles Au-Ag. Leurs réponses optiques stationnaire et transitoire sont analysées en fonction de la morphologie des NP.Dans les développements évoqués ci-dessus, l’exaltation de champ proche autour des NP plasmoniques joue un rôle clé. Cependant, l’étude de la modulation transitoire du champ proche est limitée par l'incapacité des outils numériques usuels à saisir de faibles variations de la permittivité des NP. Nous mettons en œuvre une méthode FDTD basée sur les paires pole-résidu complexes-conjugués pour pouvoir simuler l’évolution temporelle de la topographie du champ proche plasmonique. Au-delà, le mode LSPR peut être couplé à un mode photonique dans une cavité hybride pour concevoir des fonctionnalités photoniques optiquement contrôlées. Le couplage d'un réseau 2D de nanobâtonnets d'or parallèles avec le mode de défaut d'une cavité d’un cristal photonique 1D est étudié théoriquement. L'anisotropie optique permet de jouer avec plusieurs degrés de liberté comme la polarisation du champ. La modulation ultrarapide de la réponse optique prédite dans de telles nanostructures hybrides ouvre la possibilité de leur optimisation future pour la conception de capteurs résolus en temps<br>The remarkable properties associated with the localized plasmon resonance (LSPR) in noble metal nanoparticles (NPs) make plasmonics an important topic with multiple applications. When NPs are illuminated by ultrashort laser pulses they undergo a rapid dynamics of energy exchanges which leads to the ultrafast variation of their optical properties, associated with other effects such as broadband photoluminescence, hyperlocalized heat release, electron photoemission, production of reactive oxygen species and nano-cavitation. The design of complex hybrid nanostructures can enable us to tailor the plasmonic properties as to optimize the applications. We have studied some hybrid nanostructures by broadband pump-probe absorption spectroscopy and a dedicated modeling: AuNP-decorated silica fibers and core-shell Au-Ag NPs. Their stationary and transient optical responses are analyzed depending on the NP morphology.In the developments evoked above the enhanced near field around plasmonic NPs plays a key role. However, the study of the ultrafast transient modulation of the near field is limited by the inability of the conventional numerical tools to catch the small variations of the NP permittivity. Here, a complex-conjugate pole-residue pair based FDTD method is successfully implemented to simulate the time-dependence of the plasmonic near-field topography. Beyond, the LSPR mode can be resonantly coupled with a photonic mode in a hybrid microcavity for conceiving optically-controlled photonic functionalities. The coupling of a 2D array of parallel gold nanorods with the defect mode of a 1D photonic crystal cavity is investigated theoretically. The optical anisotropy enables us to play with several degrees of freedom like field polarization. The ultrafast modulation of the optical response that is predicted in such hybrid nanostructures opens the possibility of their future optimization for designing time-resolved sensors
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Scales, Christine. "Magneto-plasmons in optical slab waveguides." Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26765.
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The effect of an externally applied magnetic field on the propagation characteristics of a plasmon-polariton wave supported by an infinitely wide thin metal waveguide was investigated. In order to do so, the dispersion relation was derived, from Maxwell's equations, enabling accurate modelling of the situation of interest. The general dispersion relation, including the constraint equation, for magneto-plasmons was derived in general, and then, specifically for a magnetic field applied along three orthogonal cartesian axes. The losses in the metal were included in the dispersion equation so that a better understanding of the influence of an externally applied magnetic field may be provided.
The dispersion relation is used as the basis of a software model of magneto-plasmons in thin metal films. This model is validated against specific cases in the literature with and without an externally applied magnetic field. The specific formulations in the literature were deemed to be incorrect, and have been corrected and the results have been interpreted. The model is then used to simulate thin gold films bounded by silicon dioxide at an infrared wavelength. The modelling results include the effect of the externally applied magnetic field on the propagation constant and the corresponding field components for all three Cartesian orientations of externally applied magnetic field. The results from these simulations are presented and interpreted. (Abstract shortened by UMI.)
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Marques, Antonio Neudson Lima. "Teoria diagramÃtica para plasmons em semicondutores." Universidade Federal do CearÃ, 2004. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=4066.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior<br>CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior<br>O cÃlculo da luminescÃncia em um semicondutor de gap direto à feito por dois mÃtodos e, sÃo realizadas comparaÃÃes dos resultados teÃricos obtidos. No primeiro caso, o mÃtodo das funÃÃes de Green à utilizado e a interaÃÃo coulombiana entre o sistema elÃtron-buraco que compÃe o plasma, à tratada atravÃs da AproximaÃÃo de Fases AleatÃrias. Como resultado importante obtemos a funÃÃoo dielÃtrica, com a qual podemos associar a resposta Ãptica do sistema Ãs excitaÃÃes externas. No segundo caso, usamos a teoria diagramÃtica para obter a relaÃÃo de dispersÃo para o semicondutor de gap direto.
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Lereu, Aude L. "Couplages assistés par plasmons de surface." Dijon, 2005. http://www.theses.fr/2005DIJOS053.
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Kociak, Mathieu. "Supraconductivite et plasmons dans les nanotubes." Phd thesis, Paris 11, 2001. http://www.theses.fr/2001PA112101.
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Dans cet ouvrage, nous presentons deux types d'experiences sur des nanotubes uniques caracterises parallelement par microscopie electronique en transmission. Le premier type d'experiences a ete mene sur des jonctions metal-nanotube de carbone-metal. La resistance differentielle de ces jonctions a ete mesuree a des temperatures allant de 50 mk a 1k. Lorsque les contacts sont supraconducteurs, nous avons montre qu'il etait possible d'induire par effet de proximite un supercourant au sein d'une corde ou d'un tube monoparoi. Lorsque les contacts sont normaux, nous avons pu mettre en evidence une transition supraconductrice intrinseque dans des cordes de nanotubes a une temperature critique de environ 500 mk. Nous avons discute ces resultats en prenant en compte les parametres modifiant la supraconductivite dans des systemes a faible nombre de canaux. Nous avons montre ainsi la possibilite d'observer un transport ohmique et coherent dans des nanotubes de carbone. Dans le second type d'experiences, nous avons cherche a caracteriser la reponse dielectrique de nanotubes multifeuillets de carbone, nitrure de bore (bn) et de disulfure de tungstene (ws 2). Pour cela, nous avons effectue des mesures de spectroscopie de perte d'energie resolues spatialement. Nous avons d'abord montre l'adequation d'une description classique pour rendre compte des proprietes dielectriques (1-50 ev) de nanotubes a l'aide de mesures sur des nanotubes de carbone et bn. L'importance de l'anisotropie locale dans l'interpretation des spectres a ete demontree. Les memes experiences menees cette fois sur des tubes de ws 2 de parois d'epaisseur differentes a permis de mettre en evidence l'existence de modes electromagnetiques de surface de symetrie bien determinee resultant du couplage des modes des surfaces internes et externes. Une meme interpretation a permis de d'analyser la reponse dielectrique de tubes de carbone en termes classiques, meme lorsque la paroi se reduit a un plan monoatomique.
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Moazzezi, Mojtaba. "Quantum Coherence Effects Coupled via Plasmons." Thesis, University of North Texas, 2018. https://digital.library.unt.edu/ark:/67531/metadc1404550/.
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This thesis is an attempt at studying quantum coherence effects coupled via plasmons. After introducing the quantum coherence in atomic systems in Chapter 1, we utilize it in Chapter 2 to demonstrate a new technique of detection of motion of single atoms or irons inside an optical cavity. By taking into account the interaction of coherences with surface plasmonic waves excited in metal nanoparticles, we provide a theoretical model along with experimental data in Chapter 3 to describe the modification of Raman spectra near metal nanoparticles. We show in chapter 4 that starting from two emitters, coupled via a plasmonic field, the symmetry breaking occurs, making detectable the simultaneous existence of the fast super-radiance and the slow sub-radiance emission of dye fluorescence near a plasmonic surface. In Chapter 5, we study the photon statistics of a group of emitters coupled via plasmons and by the use of quantum regression theorem, we provide a theoretical model to fully investigate the dependence of photon bunching and anti-bunching effects to the interaction between atoms, fields and surrounding mediums.
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Bhatta, Hari Lal. "UV Magnetic Plasmons in Cobalt Nanoparticles." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1505221/.
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The main goals of this research were to fabricate magnetic cobalt nanoparticles and study their structural, crystal structure, optical, and magnetic properties. Cobalt nanoparticles with average particle size 8.7 nm were fabricated by the method of high temperature reduction of cobalt salt utilizing trioctylphosphine as a surfactant, oleic acid as a stabilizer, and lithium triethylborohydride as a reducing reagent. Energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the formation of cobalt nanoparticles. High resolution transmission electron microscopy images show that Co NPs form both HCP and FCC crystal structure. The blocking temperature of 7.6 nm Co NPs is 189 K. Above the blocking temperature, Co NPs are single domain and hence showed superparamagnetic behavior. Below the blocking temperature, Co NPs are ferromagnetic. Cobalt nanoparticles with a single-domain crystal structure support a sharp plasmon resonance at 280 nm. Iron nanoparticles with average particle size 4.8 nm were fabricated using chemical reduction method show plasmon resonance at 266 nm. Iron nanoparticles are ferromagnetic at 6 K and superparamagnetic at 300 K.
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Vernon, Kristy C. "Strongly localised plasmons in metallic nanostructures." Thesis, Queensland University of Technology, 2008. https://eprints.qut.edu.au/19318/2/Kristy_Vernon_Citation.pdf.
Full textAbstract:
Strongly localised plasmons in metallic nano-structures offer exciting characteristics for guiding and focusing light on the nano-scale, opening the way for the development of new types of sensors, circuitry and improved resolution of optical microscopy. The work presented in this thesis focuses on two major areas of plasmonics research - nano-focusing structures and nano-sized waveguides. Nano-focusing structures focus light to an area smaller than the wavelength and will find applications in sensing, efficiently coupling light to nano-scale devices, as well as improving the resolution of near field microscopy. In the past the majority of nano-focusing structures have been nano-scale cones or tips, which are capable of focusing light to a spot of nano-scale area whilst enhancing the light field. The alternatives are triangular nano-focusing structures which have received far less attention, and only one type of triangular nano-focusing structure is known – a sharp V-groove in a metal substrate. This structure focuses light to a strip of nano-scale width, which may lead to new applications in microscopy and sensing. The difficulty with implementing the V-groove is that the structure is not robust and is quite difficult to fabricate. This thesis aims to develop new triangular nano-focusing devices which will overcome these difficulties, whilst still producing an intense light source on the nano-scale. The two proposed structures presented in this thesis are a metallic wedge submerged in uniform dielectric and a tapered metal film lying on a dielectric substrate, the latter being the easier to fabricate and the more structurally sound and robust. The investigation is performed using the approximation of continuous electrodynamics, the geometrical optics approximation and the zero-plane method. The second aim of this thesis is to investigate plasmonic waveguides and couplers for the development of nano-optical circuitry, more compact photonic devices and sensors. The research will attempt to fill the gaps in the current knowledge of the V-groove waveguide, which consists of a sharp triangular groove in a metal substrate, and the gap plasmon waveguide, which consists of a rectangular slot in a thin metal film. The majority of this work will be performed using the author’s in house finite-difference time-domain algorithm and FEMLAB as well as the effective medium method and geometric optics approximation. The V-groove may be used as either a nano-focusing or waveguiding device. As a waveguide the V-groove is one of the most promising plasmonic waveguides in the optical regime. However, there exist quite a number of gaps in the current knowledge of V-groove waveguides which this thesis will attempt to fill. In particular, the effect of rounded groove tip on plasmon propagation has been assessed for the V-groove. The investigation of rounded groove tip is important, as due to modern fabrication processes it’s not possibly to produce an infinitely sharp groove, and the existing literature has not considered the impact of this problem. The thesis will also investigate the impacts of the inclusion of dielectric filling in the groove on plasmon propagation parameters. This research will be important for optimising the propagation characteristics of the mode for certain applications, but it may also lead to easier methods of fabricating the V-groove device and prevent oxidation of the metal film. The gap plasmon waveguide is easier to fabricate than the V-groove, and is a new type of sub-wavelength waveguide which displays many advantages over other types of plasmon waveguides, including ease of fabrication, almost 100% transmission around sharp bends, sub-wavelength localisation and long propagation distances of the guided mode, etc. This waveguide may prove invaluable in the development of compact photonic devices. In the past the modes supported by this structure were not thoroughly analysed and the possibility of using this structure to develop sub-wavelength couplers for sensing and nano-optical circuits was not considered in detail. This thesis aims to resolve these issues. In conclusion, the results of this thesis will lead to a better understanding of Vgroove and gap plasmon waveguide devices for the development of nano-optical circuits, compact photonic devices and sensors. This thesis also proposes two new nano-focusing structures which are easier to fabricate than the V-groove structure and will lead to applications in sensing, coupling light efficiently into nano-scale devices and improving the resolution of near-field microscopy.
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Vernon, Kristy C. "Strongly localised plasmons in metallic nanostructures." Queensland University of Technology, 2008. http://eprints.qut.edu.au/19318/.
Full textAbstract:
Strongly localised plasmons in metallic nano-structures offer exciting characteristics for guiding and focusing light on the nano-scale, opening the way for the development of new types of sensors, circuitry and improved resolution of optical microscopy. The work presented in this thesis focuses on two major areas of plasmonics research - nano-focusing structures and nano-sized waveguides. Nano-focusing structures focus light to an area smaller than the wavelength and will find applications in sensing, efficiently coupling light to nano-scale devices, as well as improving the resolution of near field microscopy. In the past the majority of nano-focusing structures have been nano-scale cones or tips, which are capable of focusing light to a spot of nano-scale area whilst enhancing the light field. The alternatives are triangular nano-focusing structures which have received far less attention, and only one type of triangular nano-focusing structure is known – a sharp V-groove in a metal substrate. This structure focuses light to a strip of nano-scale width, which may lead to new applications in microscopy and sensing. The difficulty with implementing the V-groove is that the structure is not robust and is quite difficult to fabricate. This thesis aims to develop new triangular nano-focusing devices which will overcome these difficulties, whilst still producing an intense light source on the nano-scale. The two proposed structures presented in this thesis are a metallic wedge submerged in uniform dielectric and a tapered metal film lying on a dielectric substrate, the latter being the easier to fabricate and the more structurally sound and robust. The investigation is performed using the approximation of continuous electrodynamics, the geometrical optics approximation and the zero-plane method. The second aim of this thesis is to investigate plasmonic waveguides and couplers for the development of nano-optical circuitry, more compact photonic devices and sensors. The research will attempt to fill the gaps in the current knowledge of the V-groove waveguide, which consists of a sharp triangular groove in a metal substrate, and the gap plasmon waveguide, which consists of a rectangular slot in a thin metal film. The majority of this work will be performed using the author’s in house finite-difference time-domain algorithm and FEMLAB as well as the effective medium method and geometric optics approximation. The V-groove may be used as either a nano-focusing or waveguiding device. As a waveguide the V-groove is one of the most promising plasmonic waveguides in the optical regime. However, there exist quite a number of gaps in the current knowledge of V-groove waveguides which this thesis will attempt to fill. In particular, the effect of rounded groove tip on plasmon propagation has been assessed for the V-groove. The investigation of rounded groove tip is important, as due to modern fabrication processes it’s not possibly to produce an infinitely sharp groove, and the existing literature has not considered the impact of this problem. The thesis will also investigate the impacts of the inclusion of dielectric filling in the groove on plasmon propagation parameters. This research will be important for optimising the propagation characteristics of the mode for certain applications, but it may also lead to easier methods of fabricating the V-groove device and prevent oxidation of the metal film. The gap plasmon waveguide is easier to fabricate than the V-groove, and is a new type of sub-wavelength waveguide which displays many advantages over other types of plasmon waveguides, including ease of fabrication, almost 100% transmission around sharp bends, sub-wavelength localisation and long propagation distances of the guided mode, etc. This waveguide may prove invaluable in the development of compact photonic devices. In the past the modes supported by this structure were not thoroughly analysed and the possibility of using this structure to develop sub-wavelength couplers for sensing and nano-optical circuits was not considered in detail. This thesis aims to resolve these issues. In conclusion, the results of this thesis will lead to a better understanding of Vgroove and gap plasmon waveguide devices for the development of nano-optical circuits, compact photonic devices and sensors. This thesis also proposes two new nano-focusing structures which are easier to fabricate than the V-groove structure and will lead to applications in sensing, coupling light efficiently into nano-scale devices and improving the resolution of near-field microscopy.
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Rolly, Brice. "Subwavelength photonic resonators for enhancing light-matter interactions." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4366.
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Les antennes optiques sont des structures qui permettent de convertir, dans les deux sens, l'énergie électromagnétique entre un faisceau lumineux et une source (ou un absorbeur) localisée en son sein. L'utilisation de résonateurs de taille inférieure à la longueur d'onde permet de réaliser cette fonction de manière efficace, sur une bande spectrale relativement étendue, et d'avoir une antenne compacte.La bonne connaissance des propriétés optiques de ces résonateurs, pris séparément, et de leurs couplages entre eux, est nécessaire pour pouvoir proposer des designs d'antenne efficaces.Dans cette thèse, en se basant sur la décomposition multipolaire des champs et sur la méthode de la matrice-T, on obtient des solutions analytiques rigoureuses pour des résonateurs sphériques et homogènes, dont on tire des modèles simplifiés, intuitifs, et proches de la solution exacte des équations de Maxwell.Entre autre résultats, ces modèles nous ont permis de proposer un design d'antenne optique compacte, directive, à taux de désexcitation et rendement quantique élevés en utilisant une structure hybride métal-diélectrique. Des collaborations avec des expérimentateurs ont permis de valider, d'une part les caractéristiques de chromophores auto-assemblés par ADN (S. Bidault à Paris), et d'autre part, la possibilité d'utiliser plusieurs résonances électriques et magnétiques combinées (supportées par des sphères diélectriques d'indice modéré, n=2,45) pour réfléchir ou bien collecter le rayonnement d'un émetteur dipôle électrique placé à proximité (expérience menée dans le régime micro-ondes par R. Abdeddaim et J-M. Geffrin)<br>Optical antennas are structures able to convert, in both ways, electromagnetic energy between a light beam and a source (or absorber) placed in the structure. The use of sub-wavelength resonators enables one to realize this function in an efficient way, on relatively broad bandwidths, and to have a compact design. A good understanding of the optical properties of such resonators, taken individually, and of their couplings, is thus necessary in order to propose efficient optical antenna designs. In this manuscript, using a multipole decomposition of the fields and a T-matrix method, we obtain rigorous analytical solutions for spherical, homogeneous resonators, from which we deduce simplified, intuitive models that are still very close to the exact resolution of the Maxwell equations.Among other results, those models enabled us to propose a nanoantenna design that is at once compact, radiative and efficient, by using a hybrid metallo-dielectric structure. Some collaborations with experimental groups enabled us to validate, on the one hand, the optical characteristics of hybrid chromophores that are self-assembled using a DNA template (S. Bidault, Paris), and on the other hand, the possibility of using multiple combined electric and magnetic resonances (supported by dielectric spheres of moderate refractive index, n=2.45) in order to reflect, or more importantly collect, radiation coming from an electric dipole emitter placed nearby (the experiment was realized in the microwave regime by R. Abdeddaim and J-M. Geffrin)
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Ameling, Ralf [Verfasser], and Harald [Akademischer Betreuer] Giessen. "Microcavity plasmonics / Ralf Ameling. Betreuer: Harald Giessen." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2011. http://d-nb.info/1014785200/34.
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Hamza, Taha Mohamed. "Doped ZnO nanostructures for Mid Infrared plasmonics." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC051/document.
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L'objectif de ce travail est de réaliser des substrats pour l’effet SEIRA (surface enhanced IR absorption) pour mesurer de faibles volumes de gaz ambiants possédant une signature moléculaire de 3,3 μm à 5,1 μm en exploitant la forte amplification de champ électrique due à la résonance plasmon de surface localisés. A cette fin, nous avons démontré la modulation des résonances de plasmon de surface localisées MIR (LSPR) dans les nanocristaux de ZnO dopés (NCs) dopés à Ga ou Al ainsi que dans des nanofils (NWs) de ZnO dopés Ga (GZO) et dans des nanofils coeur/coquille de ZnO/GZO. En ce qui concerne l’accordabilité de MIR LSPR dans les NC, nous avons modulé la résonance plasmon de surface dans des NC de ZnO dopés Ga et Al, de 3 à 5 μm en faisant varier la teneur en Al et en Ga de 3 à 9 at.%. L’incorporation des dopants s’est révélée homogène jusqu’à 6%. Au-delà (9%), l’incorporation était fortement hétérogène, révélant que la limite de solubilité était atteinte. Les NC présentent une faible activation des impuretés. L'activation était aussi faible que 8%. Les LSPR présentaient également un fort élargissement (largeur-à-mi-hauteur FWHM). Pour accroitre l'activation des dopants, nous avons synthétisés les NC dans des conditions pauvres en O et en passivant les NC synthétisés dans des conditions riches en O (en les isolant dans des matrices telles que Al2O3 et SiO2). Nous avons ainsi augmenté l'activation de 8% à 20% pour les deux stratégies. De plus, l'incorporation des NC dans les matrices a réduit l'élargissement spectral de moitié (de 2200 cm-1 pour les NC déposés à 1100 cm-1 pour les NC noyés en matrice). En correspondance, les effets d’auto-assemblage des nanocristaux sur leur LSPR ont été modélisés par simulation FDTD. Cela a fourni des indications quant aux mécanismes responsable de l’élargissement inhomogènes des LSPR de nanocristaux de GZO. Outre les nanoparticules, nous avons étudié des nanofils ZnO dopés Ga (GZO) et coeur/coquille (ZnO/GZO) synthétisés par CVD d’organométalliques . La première conclusion importante est que le gallium produit un fort effet surfacatnt lors de la croissance MOCVD de GZO. Au lieu de former des nanofils de section hexagonale, l’introduction de Ga modifie nettement l’énergie de surface des faces latérales et conduit à al formation de structures de type « sapins de Noël ». Ce constat est aussi valable pour les coquilles de GZO déposées sur coeur de ZnO. Dans ce cas, les coquilles démouillent et forment des structures hiérarchiques en branches. Concernant les propriétés optiques de ces objets, les mesures de FTIR-photo acoustiques ont démontré une signature d’absorption reliée à la présence de Ga et pouvant être accordée selon la teneur en Ga. Cette absorption reproduit le comportement d’une résonance plasmon de surface. Cette résonance a pu être accordée de 1600 à 1900 cm-1<br>The scope of this thesis is about developing SEIRA (surface enhanced IR absorption) platform to probe low volumes of environmental gases that possess molecular signature from 3.3 μm to 5.1 μm leveraging the high field amplification of localised surface plasmon resonance (LSPR). To realise SEIRA, we demonstrated tuning MIR LSPR in Al or Ga doped ZnO nanocrystals (NCs) as well as in GZO or core-shell (ZnO/GZO) nanowires (NWs). Regarding tuning MIR LSPR in NCs, we demonstrated tunable MIR LSPR in Ga and Al doped ZnO NCs from 3 to 5 μm varying the Al or Ga content from 3 to 9 at.%. The incorporation of dopant was homogeneous up to 6%. At 9% dopant concentration, the incorporation was inhomogeneous, revealing the solubility limit has been reached. However, the NCs exhibited low activation of impurities. The activation was as low as 8%. The LSPR were characterised by large broadening as well. In order to enhance the dopant activation, we synthesized the NCs in O-poor conditions as well as passivated the NCs fabricated in O-rich condictions (by isolating and embedding them in matrices such as Al2O3 and SiO2 matrices). Both strategies improved the dopant activation from 8% up to 20%. Moreover, for assemblies of NCs dispersed in matrices, the broadening (FWHM) of the LSPR was reduced by half (from 2200 cm-1 in as-deposited NCs to 1100 cm-1 in embedded NCs). Correspondingly, the effect of the self-assembly of the nanocrystals on their LSPR was modeled by FDTD simulation and provided hindsight into the mechanisms responsible for the heterogeneous broadening of the LSPR. Finally, we have studied Ga-doped ZnO (GZO) and core-shell (ZnO/GZO) NW synthesized by MOCVD. The first important conclusion is that Ga plays a major surfactant role during the MOCVD growth of GZO. Instead of leading to hexagonal NWs, the introduction of Ga during the synthesis led to faceted “Christmas-tree” like architectures. The same observation held for core-shell ZnO-GZO nanowires; in the latter case, the GZO shell resulted in a dewetting branched architecture. Regarding their optical properties, photo-acoustic FTIR measurements revealed an absorption feature related to the Ga content, likely to be assigned to a plasmonic effect. This resonance could be tuned from 1600 to 1900 cm
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Steuwe, Christian. "Nonlinear photonics in biomedical imaging and plasmonics." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708016.
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Cantono, Giada. "Relativistic Plasmonics for Ultra-Short Radiation Sources." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS353/document.
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La plasmonique étudie le couplage entre le rayonnement électromagnétique et les oscillations collectives des électrons dans un matériel. Les plasmons de surface (SPs), notamment, ont la capacité de concentrer le champ électromagnétique sur des distances micrométriques, ce qui les rend intéressants pour le développement des dispositifs photoniques les plus novateurs. 'Etendre l'excitation de SPs au régime de champs élevés, où les électrons oscillent à des vitesses relativistes, ouvre des perspectives stimulantes pour la manipulation de la lumière laser ultra-intense et le développement de sources de rayonnement énergétiques et à courte durée. En fait, l'excitation de modes résonnants du plasma est l'une des stratégies possibles pour transférer efficacement l'énergie d'une impulsion laser ultra-puissante à une cible solide, cela étant parmi les défis actuels dans la physique de l’interaction laser-matière à haute intensité. Dans le cadre de ces deux sujets, ce travail de thèse démontre la possibilité d'exciter de façon résonnante des plasmons de surface avec des impulsions laser ultra-intenses. Elle étudie comment ces ondes peuvent à la fois accélérer de paquets d'électrons relativistes le long de la surface de la cible mais aussi augmenter la génération d'harmoniques d'ordre élevé de la fréquence laser. Ces deux processus ont été caractérisés avec de nombreuses expériences et simulations numériques. En utilisant un schéma d’interaction standard de la plasmonique classique, les SPs sont excités sur des cibles dont la surface présente une modulation périodique régulière à l'échelle micrométrique (cibles réseau). Dans ce cas, les propriétés de l'émission d'électrons tout comme celles des harmoniques permettent d’envisager leur utilisation dans des application pratiques. En réussissant à dépasser les principaux problèmes conceptuels et techniques qui jusqu'au présent avaient empêché l'application d'effets plasmoniques dans le régime de champs élevés, ces résultats apportent un intérêt nouveau à l'exploration de la Plasmonique Relativiste<br>Plasmonics studies how the electromagnetic radiation couples with the collective oscillations of the electrons within a medium. Surface plasmons (SPs), in particular, have a well-established role in the development of forefront photonic devices, as they allow for strong enhancement of the local EM field over sub-micrometric dimensions. Promoting the SP excitation to the high-field regime, where the electrons quiver at relativistic velocities, would open stimulating perspectives for the both the manipulation of ultra-intense laser light and the development of energetic, short radiation sources. Indeed, the excitation of resonant plasma modes is a possible strategy to efficiently deliver the energy of a high-power laser to a solid target, this being among the current challenges in the physics of highly-intense laser-matter interaction. Gathering these topics, this thesis demonstrates the opportunity of resonant surface plasmon excitation at ultra-high laser intensities by studying how such waves accelerate bunches of relativistic electrons along the target surface and how they enhance the generation of high-order harmonics of the laser frequency. Both these processes have been investigated with numerous experiments and extensive numerical simulations. Adopting a standard configuration from classical plasmonics, SPs are excited on solid, wavelength-scale grating targets. In their presence, both electron and harmonic emissions exhibit remarkable features that support the conception of practical applications. Putting aside some major technical and conceptual issues discouraging the applicability of plasmonic effects in the high-field regime, these results are expected to mark new promises to the exploration of Relativistic Plasmonics
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TORRE, IACOPO. "Hydrodynamics and plasmonics in two-dimensional materials." Doctoral thesis, Scuola Normale Superiore, 2018. http://hdl.handle.net/11384/85904.
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This Thesis is devoted to the study of two different aspects of electron behavior in two-dimensional
materials, namely hydrodynamic electron transport and plasmon propagation. The Thesis is structured
as follows. In Chapter 1 the main experimental facts that motivated our work on electron hydrodynamics
and plasmonics are presented and critically discussed. Chapter 2 contains our main results on
hydrodynamic electron transport. After deriving the basic equations of the electron hydrodynamics and
discussing their limit of applicability, we use them to quantify the impact of two different transport
coffcients, the shear and Hall viscosities of the electron liquid, on steady-state transport. Our results
are used to propose experimental protocols that allow an experimental determination of these transport
coeffcients. Chapter 3 deals with plasmon propagation through inhomogeneous media. We consider
three dfferent geometries: an interface between two dfferent materials, a one dimensional perturbation,
and a zero dimensional perturbation in an otherwise uniform electron system. We calculate scattering
observables for plasmons in these geometries. For the interface geometry we also investigated the presence
of plasmonic bound states localized near the interface, while for the second and third geometries we
quantify the impact of non-local fects. Chapter 4 presents a theory of chiral plasmons in materials with
a non-trivial Berry curvature in the electronic band structure. We firstly employ the results of Chapter 3
to obtain a semi-classical theory of Chiral Berry Plasmons (CBPs) at a generic interface between two
materials having different Berry uxes across the Fermi surface. We then test the impact of different
types of screened electron-electron interaction, and of a finite damping rate on the dispersion and lifetime
of CBPs.
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Beránek, Jiří. "Povrchové plazmonové rezonance na koloidních nanočásticích." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230613.
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The presented diploma thesis is focused on the Localized Surface Plasmons (LSP). The far-field optical response of the colloidal solutions of gold nanoparticles caused by LSP was investigated and compared with the numerical calculations. For the simulations, the Discrete Dipole Approximation (DDA) and Finite-Difference Time Domain (FDTD) techniques were employed. In particular, the shape and size effects of spherical particles and nanorods were studied. The simulations performed by both methods are in a good agreement for the spheres. For the nanorods, the resonance was found to be affected markedly by their geometry. Also, broader resonance peaks were found. This effect was assigned to the sample size distribution and its influence is discussed by comparing the simulations with experiments. In addition, synthesis of nanorods was carried out as well. Finally, the results on the study of optical properties of silver clusters formed under equilibrium conditions are presented.