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Dissertations / Theses on the topic 'Plasmonen'

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Published: 4 June 2021
Last updated: 8 February 2022

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1

Benten, Wolfgang. "Plasmonen in einzelnen oxidgetragenen Edelmetallpartikeln." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=979941954.

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2

Langer, Thomas [Verfasser]. "Niedrigdimensionale Plasmonen in epitaktischen Graphenlagen / Thomas Langer." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2012. http://d-nb.info/1021189049/34.

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3

Kirste, Ronny [Verfasser], and Axel [Akademischer Betreuer] Hoffmann. "Gruppe-III-Nitride: Phononen, Plasmonen, Polarität / Ronny Kirste. Betreuer: Axel Hoffmann." Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2012. http://d-nb.info/1018764992/34.

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4

Krieg, Ulrich [Verfasser]. "1D-Plasmonen in Ag-Nanodrähten auf vicinalem Si(557) / Ulrich Krieg." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover (TIB), 2014. http://d-nb.info/1058240730/34.

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5

Sprafke, Alexander Nicolas [Verfasser]. "Optische Nahfeld-Wechselwirkungen von Plasmonen mit ihrer Umgebung / Alexander Nicolas Sprafke." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2014. http://d-nb.info/1052254497/34.

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6

Sprafke, Alexander [Verfasser]. "Optische Nahfeld-Wechselwirkungen von Plasmonen mit ihrer Umgebung / Alexander Nicolas Sprafke." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2014. http://nbn-resolving.de/urn:nbn:de:hbz:82-opus-50008.

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7

Bomm, Jana. "Von Gold Plasmonen und Exzitonen : Synthese, Charakterisierung und Applikationen von Gold Nanopartikeln." Phd thesis, Universität Potsdam, 2012. http://opus.kobv.de/ubp/volltexte/2013/6640/.

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In dieser Arbeit wurden sphärische Gold Nanopartikel (NP) mit einem Durchmesser größer ~ 2 nm, Gold Quantenpunkte (QDs) mit einem Durchmesser kleiner ~ 2 nm sowie Gold Nanostäbchen (NRs) unterschiedlicher Länge hergestellt und optisch charakterisiert. Zudem wurden zwei neue Synthesevarianten für die Herstellung thermosensitiver Gold QDs entwickelt werden. Sphärische Gold NP zeigen eine Plasmonenbande bei ~ 520 nm, die auf die kollektive Oszillation von Elektronen zurückzuführen ist. Gold NRs weisen aufgrund ihrer anisotropen Form zwei Plasmonenbanden auf, eine transversale Plasmonenbande bei ~ 520 nm und eine longitudinale Plasmonenbande, die vom Länge-zu-Durchmesser-Verhältnis der Gold NRs abhängig ist. Gold QDs besitzen keine Plasmonenbande, da ihre Elektronen Quantenbeschränkungen unterliegen. Gold QDs zeigen jedoch aufgrund diskreter Energieniveaus und einer Bandlücke Photolumineszenz (PL). Die synthetisierten Gold QDs besitzen eine Breitbandlumineszenz im Bereich von ~ 500-800 nm, wobei die Lumineszenz-eigenschaften (Emissionspeak, Quantenausbeute, Lebenszeiten) stark von den Herstellungs-bedingungen und den Oberflächenliganden abhängen. Die PL in Gold QDs ist ein sehr komplexes Phänomen und rührt vermutlich von Singulett- und Triplett-Zuständen her. Gold NRs und Gold QDs konnten in verschiedene Polymere wie bspw. Cellulosetriacetat eingearbeitet werden. Polymernanokomposite mit Gold NRs wurden erstmals unter definierten Bedingungen mechanisch gezogen, um Filme mit optisch anisotropen (richtungsabhängigen) Eigenschaften zu erhalten. Zudem wurde das Temperaturverhalten von Gold NRs und Gold QDs untersucht. Es konnte gezeigt werden, dass eine lokale Variation der Größe und Form von Gold NRs in Polymernanokompositen durch Temperaturerhöhung auf 225-250 °C erzielt werden kann. Es zeigte sich, dass die PL der Gold QDs stark temperaturabhängig ist, wodurch die PL QY der Proben beim Abkühlen (-7 °C) auf knapp 30 % verdoppelt und beim Erhitzen auf 70 °C nahezu vollständig gelöscht werden konnte. Es konnte demonstriert werden, dass die Länge der Alkylkette des Oberflächenliganden einen Einfluss auf die Temperaturstabilität der Gold QDs hat. Zudem wurden verschiedene neuartige und optisch anisotrope Sicherheitslabels mit Gold NRs sowie thermosensitive Sicherheitslabel mit Gold QDs entwickelt. Ebenso scheinen Gold NRs und QDs für die und die Optoelektronik (bspw. Datenspeicherung) und die Medizin (bspw. Krebsdiagnostik bzw. -therapie) von großem Interesse zu sein.
In this thesis, the synthesis and optical characterization of spherical gold nanoparticles (NP) with diameters larger than ~ 2 nm, gold quantum dots (QDs) with diameters smaller than ~ 2 nm and gold nanorods (NRs) with different lengths are presented. In addition, a novel one-pot synthesis for the preparation of thermosensitive gold QDs is introduced. Gold NP solutions appear red colored due to their strong absorption in the visible range at ~ 520 nm. This absorption band is a result of surface plasmon resonance, which is caused by the coherent oscillation of conduction band electrons induced by an electromagnetic field. In contrast to spherical gold NPs, gold NRs show two surface plasmon bands due to their anisotropic shape, a transverse plasmon band at ~ 520 nm and a longitudinal plasmon band depending on the aspect ratio (length-to-width-ratio) of the gold NRs. If the size of the gold NPs decreases to values below ~ 2 nm, quantum-size confinement occurs and the surface plasmon band disappears. Additionally, the overlap between conduction band and valence band disappears, discrete electronic levels arise and a band gap is created. As a consequence of quantum confinement, the gold QDs show photoluminescence (PL) upon UV-irradiation. The gold QDs synthesized via the one-pot synthesis exhibit a broadband luminescence between 500 nm and 800 nm. The luminescence properties (emission peak, quantum yield, lifetime) strongly depend on the synthetic parameters like reaction temperature, stoichiometry and the surface ligand. Gold NRs and gold QDs were incoroporated into different polymers (e.g. cellulose triacetate). Polymer nanocomposite films showing optical anisotropy are obtainded by stretching polymer films containing gold NRs uniaxial in a tensile test machine. In addition to the optical characterization of gold NRs and QDs, their thermal behavior in solution as well as in different nanocomposites is studied. A shortening of the gold NRs or a transformation into spherical gold NP is observed, if the polymer nanocomposites containing gold NRs are heated above a temperature of 200 °C. The PL of the synthesized gold QDs strongly depends on the ambient temperature. An increase of PL quantum yield (QY) and PL lifetime occur, if the solutions are cooled. The best PL QY of 16.6 % was observed for octadecyl mercaptan capped gold QDs at room temperature, which could be improved to 28.6 % when cooling the solutions to -7 °C. Furthermore, optically anisotropic security labels containing gold NRs and thermosensitive security devices containing gold QDs are developed. Due to their unique optical properties, gold NRs and QDs are interesting candidates for optoelectronical as well as data storage devices and medical applications like biomedical imaging or cancer therapy.
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8

Seidel, Jan. "Propagation, Scattering and Amplification of Surface Plasmons in Thin Silver Films." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1117625135371-32372.

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Plasmons, i.e. collective oscillations of conduction electrons, have a strong influence on the optical properties of metal micro- and nanostructures and are of great interest for novel photonic devices. Here, plasmons on metal-dielectric interfaces are investigated using near-field optical microscopy and differential angular reflectance spectroscopy. Emphasis is placed on the study of plasmon interaction with individual nanostructures and on the nonlinear process of surface plasmon amplification. Specifically, plasmon transmission across single grooves in thin silver films is investigated with the help of a near-field optical microscope. It is found that plasmon transmittance as a function of groove width shows a non-monotonic behavior, exhibiting certain favorable groove widths with strongly decreased transmittance values. Additionally, evidence of groove-mediated plasmon mode coupling is observed. Spatial beating due to different plasmon wave vectors produces distinct interference features in near-field optical images. A theoretical approach explains these observations and gives estimated coupling effciencies deduced from visibility considerations. Furthermore, stimulated emission of surface plasmons induced by optical pumping using an organic dye solution is demonstrated for the first time. For this a novel twin-attenuated-total-reflection scheme is introduced. The experiment is described by a theoretical model which exhibits very good agreement. Together they provide clear evidence of the claimed process.
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9

Schertz, Florian [Verfasser]. "Nahfeld-induzierte Elektronenemissions-Mikrospektroskopie an stark gekoppelten Plasmonen und metallischen Mikrostrukturen / Florian Schertz." Mainz : Universitätsbibliothek Mainz, 2013. http://d-nb.info/1044286954/34.

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10

Edelmann, André [Verfasser]. "Ausbreitung von optischen und THz-Plasmonen auf planaren und zylindrischen Wellenleitern / André Edelmann." Hagen : Fernuniversität Hagen, 2015. http://d-nb.info/1065828683/34.

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11

Bomm, Jana [Verfasser], and Joachim [Akademischer Betreuer] Stumpe. "Von Gold Plasmonen und Exzitonen : Synthese, Charakterisierung und Applikationen von Gold Nanopartikeln / Jana Bomm. Betreuer: Joachim Stumpe." Potsdam : Universitätsbibliothek der Universität Potsdam, 2013. http://d-nb.info/1036546772/34.

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12

Scholten, Andreas [Verfasser]. "Entwicklung antikörperbasierter Biosensoren zur Detektion von Spuren in heterogener Matrix mittels der Oberflächen-Plasmonen verstärkten Fluoreszenzspektroskopie / Andreas Scholten." Köln : Deutsche Zentralbibliothek für Medizin, 2014. http://d-nb.info/1049311302/34.

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13

Renger, Jan. "Excitation, Interaction, and Scattering of Localized and Propagating Surface Polaritons." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2006. http://nbn-resolving.de/urn:nbn:de:swb:14-1153478195966-65404.

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Surface polaritons, i.e., collective oscillations of the surface charges, strongly influence the optical response at the micro- and nanoscale and have to be accounted for in modern nanotechnology. Within this thesis, certain basic phenomena involving surface polaritons are investigated by means of the semianalytical multiple-multipole (MMP) method. The results are compared to experiments. In the first part, the surface plasmon resonance (SPR) of metal nanoparticles is analyzed. This resonant collective oscillation of the free electrons in a metallic nanoparticle leads to an enhancement and confinement of the local electric field at optical frequencies. The local electric field can be further increased by tailoring the shape of the particle or by using near-field-interacting dimers or trimers of gold nanospheres. The hot spots found under such conditions increase the sensitivity of surface-enhanced Raman scattering by several orders of magnitude and simultaneously reduce the probed volume, thereby providing single-molecule sensitivity. The sub-wavelength-confined strong electromagnetic field associated with a SPR provides the basis for scattering-type near-field optical microscopy or tip-enhanced Raman spectroscopy, where the metal particle serves as a probe that is scanned laterally in the vicinity of a substrate. The presence of the latter causes a characteristic shift of the SPR towards lower frequencies. This effect originates in the near-field interaction of the surface charges on the objects. Furthermore, the excitation of higher-order modes becomes possible in case of an excitation by a strongly inhomogeneous wave, such as an evanescent wave. These modes may significantly contribute to the near field but have only very little influence on the far-field signature. Instead of using resonant probes, one may place a nonresonant probe in the vicinity of a substrate having a high density of electromagnetic surface states. This also produces a resonance of the light scattering by the system. Especially polar crystals, such as the investigated silicon carbide, feature such a high density of surface phonon polariton states in the mid-infrared spectral region, which can be excited due to the near-field interaction with a polarized particle. Thereby, a resonance is created leading to a strong increase of the electric field at the interface. In the second part of the thesis, special emphasis is put on surface plasmon polaritons (SPPs). Such propagating surface waves can be excited directly by plane waves only at patterned interfaces. This process is studied for the case of a groove. The groove breaks the translational invariance, so that the SPPs can be launched locally at the edges of the groove. Additionally, the mode(s) inside the groove are excited. These modes can basically be understood as metal-insulator-metal cavity modes. Their dispersion strongly depends on the groove width. The cavity behavior caused by the finite depth provides another degree of freedom for optimizing the SPP excitation by plane waves. Thin metallic films deposited on glass offer two different SPP waveguide modes, each of which can be addressed preferentially by a proper choice of the width of the groove. The reflection, transmission, scattering, and the conversion of the modes at discontinuities such as edges, steps, barriers, and grooves can be controlled by appropriately designing the geometry at the nanoscale. Furthermore, the excitation of SPPs at single and multiple slits in thin-film metal waveguides on glass and their propagation and scattering is shown by scanning near-field optical experiments. Such waveguide structures offer a means for transporting light in a confined way. Especially triangularly shaped waveguides can be used to guide light in sub-wavelength spaces
Die Wechselwirkung von elektromagnetischer Strahlung mit subwellenlängenkleinen Teilchen bzw. Oberflächenstrukturen ermöglicht nicht nur eine Miniaturisierung optischer Geräte, sondern erlaubt sehr interessante Anwendungen, beispielsweise in der Sensorik und Nahfeldoptik. In der vorliegenden Arbeit werden die zu Grunde liegenden Effekte im Rahmen der klassischen Elektrodynamik mit Hilfe der semianalytischen Methode der multiplen Multipole (MMP) analysiert, und die Ergebnisse werden mit Experimenten verglichen. Im ersten Teil werden Oberflächenplasmonenresonanzen (engl. surface plasmon resonance - SPR) einzelner und wechselwirkender Metallteilchen untersucht. Die dabei auftretende resonante kollektive Schwingung der freien Elektronen des Partikels bewirkt eine deutliche Erhöhung und Lokalisierung des elektromagnetischen Feldes in seiner Umgebung. Die spektrale Position und die Stärke der SPR eines Nanoteilchens, die von dessen geometrischer Form, Permittivität und Umgebung abhängen, können nur im Grenzfall sehr kleiner Teilchen elektrostatisch beschrieben werden, wohingegen der verwendete semianalytische MMP-Ansatz weitaus flexibler ist und insbesondere auch auf größere Partikel, Teilchen mit komplizierterer Form bzw. Ensembles von Partikeln anwendbar ist. Die betrachteten einzelnen kleinen (< Wellenlänge) Goldkügelchen und Silberellipsoide besitzen eine stark ausgeprägte SPR im sichtbaren optischen Bereich. Diese ist auf eine dipolartige Polarisierung des Teilchens zurückzuführen. Höhere Moden der Polarisation können entweder als Folge von Retardierungseffekten an größeren (mit der Wellenlänge vergleichbaren) Teilchen oder bei der Verwendung inhomogener (z.B. evaneszenter) Wellen angeregt werden. Partikel, die sich in der Nähe eines Substrates befinden, unterliegen der Nahfeldwechselwirkung zwischen den (lichtinduzierten) Oberflächenladungen auf der Oberfläche des Teilchens und des Substrats. Dies führt zu einer Verschiebung der SPR zu niedrigeren Frequenzen und einer Erhöhung des lokalen elektrischen Feldes. Letzteres bildet die Grundlage z.B. der spitzenverstärkten Raman-Spektroskopie und der optischen Nahfeldmikroskopie mit Streulichtdetektion. Dasselbe Prinzip bewirkt ein stark überhöhtes elektrisches Feld zwischen miteinander wechselwirkenden Nanopartikeln, welches z.B. die Sensitivität der oberflächenverstärkten Raman-Mikroskopie um mehrere Größenordnungen steigern kann. Im Gegensatz zur SPR einzelner Nanopartikel kann die Resonanz der Lichtstreuung im Fall eines Partikels in der Nähe eines Substrats aus der durch die Nahfeldwechselwirkung induzierten Anregung elektromagnetischer Oberflächenzustände entstehen. Diese wirken ihrerseits auf das Nanopartikel zurück, wobei eine resonante Lichtstreuung beobachtbar ist. Dieser, am Beispiel einer metallischen Nahfeldsonde über einem Siliziumcarbid-Substrat analysierte, Effekt ermöglicht bei einer ganzen Klasse von polaren Kristallen interessante Anwendungen in der Mikroskopie und Sensorik basierend auf der hohen Dichte von Oberflächenphononpolaritonen dieser Kristalle im mittleren infraroten Spektralbereich und deren nahfeldinduzierten Anregung. Im zweiten Teil der Arbeit werden kollektive Anregungen von Elektronen an Metalloberflächen untersucht. Die dabei auftretenden plasmonischen Oberflächenwellen (engl. surface plasmon polaritons - SPPs) weisen einen exponentiellen Abfall der Intensität senkrecht zur Grenzfläche auf. Diese starke Lokalisierung der Energie an der Oberfläche bildet die Grundlage vieler Anwendungen, z.B. im Bereich der hochempfindlichen Detektion (bio)chemischer Verbindungen oder für eine zweidimensionale Optik (engl. plasmonics). Das Aufheben der Translationsinvarianz längs der Oberfläche ermöglicht die direkte Anregung von SPPs durch ebene Wellen. Die Abhängigkeit dieser Kopplung von der Geometrie wird am Beispiel eines Nanograbens untersucht. Dabei werden neben den SPPs ebenfalls eine oder mehrere Moden im Graben angeregt. Folglich ermöglicht die geeignete Wahl der Grabengeometrie die Optimierung der Umwandlung von ebenen Wellen in SPPs. Im - in der Praxis weit verbreiteten - Fall asymmetrisch eingebetteter metallischer Dünnschichtwellenleiter existieren zwei Moden. In Abhängigkeit von der Grabenbreite kann die eine oder die andere Mode bevorzugt angeregt werden. Die Analyse der Wechselwirkung von SPPs mit Oberflächenstrukturen, z.B. Kanten, Stufen, Barrieren und Gräben, zeigt die Möglichkeit der Steuerung der Reflexions-, Transmissions- und Abstrahleigenschaften durch die gezielte Wahl der Geometrie der "Oberflächendefekte" auf der Nanoskala und deckt die zu Grunde liegenden Mechanismen und die daraus resultierenden Anforderungen bei der Herstellung neuer plasmonischer Komponenten auf. Exemplarisch wird das Prinzip der SPP-Anregung an einzelnen und mehreren Gräben in dünnen metallischen Filmen sowie der subwellenlängen Feldlokalisierung an sich verjüngenden metallischen Dünnschichtwellenleitern unter Verwendung der optischen Nahfeldmikroskopie experimentell gezeigt
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14

Ramirez, Francisco. "Surface Plasmon Hybridization in Novel Plasmonic Phenomena." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/917.

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We explore the effects of surface plasmon hybridization in graphene nanostructures and silver nanoparticles as applied to novel plasmonic phenomena. The analysis is based on the theory of surface plasmon hybridization under the boundary charges method. This method, which is based in the electrostatic approximation, has been largely used to predict the resonant frequencies in strongly coupled nanoparticle clusters. Here, we extend this formalism to analyze novel plasmonic phenomena such as the blueshift of modes in graphene plasmonics, near-field radiation, thermal transport and plasmon-induced hot carrier generation in silver nanoparticles. Furthermore, we develop analytical solutions for graphene nanodisks and metallic spheres that allow for fast and accurate modeling. The analytic models provide the basis to derive a large number of results, including prediction of hybrid eigenmodes and bandstructures, far-field response, and near-field response under thermally induced fluctuations. We predict that the strong near-filed coupling in graphene nanodisk stacks can induce a blueshift in the resonant frequencies up to the near-infrared part of the spectrum. We find that the strong near-filed coupling between disks can also lead to large values of radiative thermal conductance when thermally induced fluctuations are included. In this regard, an enhancement over the blackbody limit of up to two and four orders of magnitude was observed for co-planar and co-axial disk configurations. The strong coupling between coplanar disks was also explored for the development of plasmonic waveguides by considering long co-planar disk arrays. It was observed that the array posseses great potential for plasmonic waveguiding, with a strong degree of confinement for disks smaller than 200 nm. Thermal activation of the guided modes showed a thermal conductivity of up to 4.5 W/m K and thermal diffusivity of up to 1:4 x 10-3 m2/s. The large values of thermal diffusivity suggest the potential of graphene disk waveguides for thermotronic interconnects. The plasmon-induced hot carrier generation in silver nanosphere dimers was also studied. The modeling considered analytical solution for metallic nanospheres, from which the electrostatic potential of each sphere was obtained. Using these results, the hot carrier generation was explored under the basis of the Fermi golden rule. The results show a large number of hot carriers at the low frequency modes. This values exceed the number of generated hot carriers on a single sphere. The energy distribution of photogenerated electrons and holes showed a large energy gap that can be explored in photocatalysis and photovoltaic energy conversion.
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15

Schuster, Roman. "Electron Energy-Loss Spectroscopy on Underdoped Cuprates and Transition-Metal Dichalcogenides." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-27333.

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Die vorliegende Arbeit befasst sich mit Elektronenenergieverlustspektroskopie an unterdotierten Kupratsupraleitern und Übergangsmetalldichalcogeniden. Nach einem kurzen Abriss über die der experimentellen Methode zugrundeliegenden theoretischen Tatsachen folgen zwei experimentelle Kapitel. Für das prototypische Kupratsystem Ca2-xNaxCuO2Cl2 wird für verschiedene Dotierungskonzentrationen zunächst die Entwicklung der Ladungstransferanregungen untersucht. Man findet eine substanzielle Umverteilung des spektralen Gewichtes, verbunden mit einem starken Einbruch der Dispersion dieser Anregungen. Beides wird im Rahmen der Wechselwirkung mit Spinfreiheitsgraden innerhalb der Kupfer-Sauerstoff-Ebene diskutiert. Anschliessend erfolgt die Diskussion einer ausschließlich für zehnprozentige Dotierung auftretenden Symmetriebrechung der optischen Antwortfunktion, für die verschiedene mögliche Szenarien vorgeschlagen werden. Im Kapitel über die Dichalcogenide liegt der Fokus auf dem Verhalten des Ladungsträgerplasmons, das für alle Substanzen dieser Gruppe mit Ladungsordnung eine negative Dispersion aufweist. Dieses Verhalten läßt sich durch in-situ Interkalation zusätzlicher Ladungstraeger umkehren, so dass man eine dotierungsabhängige Plasmonendispersion erhält. Es werden verschiedene Szenarien für dieses Verhalten diskutiert
The present thesis describes electron energy-loss spectroscopy on underdoped cuprate superconductors and transition-metal dichalcogenides. After a brief introduction into the experimental method there are two experimental chapters. For the prototype cuprate system Ca2-xNaxCuO2Cl2 the behavior of the charge-transfer excitations is investigated as a function of doping. The observed substantial redistribution of spectral weight and the accompanying breakdown of their dispersion is discussed in terms of a coupling to the spin degrees of freedom within the copper-oxygen plane. For x=0.1 there is a pronounced symmetry breaking in the optical response function which is discussed in terms of different possible scenarios. The chapter on the dichalcogenides focuses on the properties of the charge-carrier plasmon which shows a negative dispersion for all representatives of this family exhibiting a charge-density wave instability. This behavior can be influenced by in-situ intercalation of additional charges, the result being a doping dependent plasmon dispersion. Several approaches to reconcile these findings are considered
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16

Lupetti, Mattia. "Plasmonic generation of attosecond pulses and attosecond imaging of surface plasmons." Diss., Ludwig-Maximilians-Universität München, 2015. http://nbn-resolving.de/urn:nbn:de:bvb:19-183678.

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Attosecond pulses are ultrashort radiation bursts produced via high harmonic generation (HHG) during a highly nonlinear excitation process driven by a near infrared (NIR) laser pulse. Attosecond pulses can be used to probe the electron dynamics in ultrafast processes via the attosecond streaking technique, with a resolution on the attosecond time scale. In this thesis it is shown that both the generation of attosecond (AS) pulses and the probing of ultrafast processes by means of AS pulses, can be extended to cases in which the respective driving and streaking fields are produced by surface plasmons excited on nanostructures at NIR wavelengths. Surface plasmons are optical modes generated by collective oscillations of the surface electrons in resonance with an external source. In the first part of this thesis, the idea of high harmonic generation (HHG) in the enhanced field of a surface plasmon is analyzed in detail by means of numerical simulations. A NIR pulse is coupled into a surface plasmon propagating in a hollow core tapered waveguide filled with noble gas. The plasmon field intensity increases for decreasing waveguide radius, such that at the apex the field enhancement is sufficient for producing high harmonic radiation. It is shown that with this setup it is possible to generate isolated AS pulses with outstanding spatial and temporal structure, but with an intensity of orders of magnitude smaller than in standard gas harmonic arrangements. In the second part, an experimental technique for the imaging of surface plasmonic excitations on nanostructured surfaces is proposed, where AS pulses are used to probe the surface field by means of photoionization. The concept constitutes an extension of the attosecond streak camera to ``Attosecond Photoscopy'', which allows space- and time-resolved imaging of the plasmon dynamics during the excitation process. It is numerically demonstrated that the relevant parameters of the plasmonic resonance buildup phase can be determined with subfemtosecond precision. Finally, the method used for the numerical solution of the Maxwell's equations is discussed, with particular attention to the problem of absorbing boundary conditions. New insights into the mathematical formulation of the absorbing boundary conditions for Maxwell's equations are provided.
Attosekundenpulse sind ultrakurze extrem-ultraviolette (XUV) Pulse, die durch einen nicht-linearen, von einer nah-infraroten (NIR) Laserquelle stimulierten Anregungsprozess erzeugt werden. Attosekundenpulse können verwendet werden, um die Elektronendynamik eines ultraschnellen Prozesses durch die ``Attosecond Streaking'' Technik zu messen, mit einer Auflösung auf der Attosekundenskala. In dieser Dissertation wird gezeigt, dass sowohl die Erzeugung von Attosekundenpulsen als auch die Messung ultraschneller Prozesse mittels Attosekundenpulse auf Fälle erweitert werden können, bei denen die Anregungs- und Streakingsfelder von Oberflächenplasmonen generiert werden, welche bei nahinfraroten Wellenlängen auf Nanostrukturen angeregt werden. Oberflächenplasmonen sind optische Moden, die aus einer kollektiven Schwingung der Elektronen an der Oberfläche in Resonanz mit einer externen Quelle entstehen. Im ersten Abschnitt dieser Dissertation wird das Konzept der High Harmonic Generation (HHG) in plasmonisch erhöhten Feldern durch numerische Simulationen analysiert. Ein NIR Puls wird mit einem Oberflächenplasmon, das sich in einem konischen, mit Edelgas gefüllten, Hohlleiter ausbreitet, gekoppelt. Die Intensität des plasmonischen Feldes steigt mit der Verringerung des Durchmessers des Hohlleiters, sodass die Felderhöhung an seiner Spitze groß genug wird, um hohe harmonische Strahlung zu generieren. Es wird nachgewiesen, dass die Herstellung von isolierten Attosekundenpulsen mit außergewöhnlichen Zeit- und Raumstrukturen möglich ist. Trotzdem ist deren Intensität um mehrere Größenordnungen niedriger als die, die in Experimenten mit fokussierten Laserpulsen erreicht werden kann. Im zweiten Abschnitt wird eine experimentelle Technik für die Abbildung plasmonischer Oberflächenanregungen vorgeschlagen, wobei Attosekundenpulse verwendet werden, um das Feld an der Oberfläche mittels ``Momentum Streaking'' der photoionisierten Elektronen zu messen. Dieses Konzept ist eine Erweiterung der ``Attosecond Streak Camera'', welches ich ``Attosecond Photoscopy'' nenne. Es ermöglicht die Abbildung eines Plasmons in Zeit und Raum während des Anregungsprozesses. Anhand von numerischen Simulationen wird es gezeigt, dass die wesentlichen Parameter des plasmonischen Resonanzaufbaus mit subfemtosekunden-Präzision bestimmt werden können. Zuletzt wird die Methode für die numerische Lösung der Maxwell-Gleichungen diskutiert, mit Fokus auf das Problem der absorbierenden Randbedingungen. Neue Einsichten in die mathematische Formulierung der Randbedingungen der Maxwell-Gleichungen werden vorgestellt.
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17

Lamowski, Simon [Verfasser]. "Theory of Plasmonic Nanostructures : Plasmon-Polaritons and Light-Induced Transport / Simon Lamowski." Konstanz : KOPS Universität Konstanz, 2020. http://d-nb.info/1233203231/34.

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18

Rahbany, Nancy. "Towards integrated optics at the nanoscale : plasmon-emitter coupling using plasmonic structures." Thesis, Troyes, 2016. http://www.theses.fr/2016TROY0003/document.

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L'objectif de ce travail de thèse est d'étudier le couplage plasmon-émetteur dans des structures plasmoniques hybrides, visant à renforcer l’interaction lumière-matière à l'échelle nanométrique. Contrairement aux cavités optiques dont le volume de modes est limité par la diffraction, les cavités plasmoniques offrent un unique avantage d’efficacité du confinement sub-longueur d'onde. Cela peut conduire à l’accroissement de la fluorescence des émetteurs placés dans leur voisinage. Pour cela, nous proposons comme dispositif de focalisation une structure intégrée d’un réseau annulaire avec des nanoantennes afin de garantir une meilleure efficacité. Ce dispositif bénéficie du couplage entre des plasmons polaritons de surface (SPP) qui se propagent à partir du réseau et des plasmons localisés de surface (LSP) localisés aux niveaux des nanoantennes afin de parvenir à une augmentation de champ plus élevée. Nous présentons une étude de caractérisation de la plate-forme plasmonique constitué du réseau de diffraction métallique annulaire, d’une nanoantenne en étoile, et la structure intégrée réseau/nanoantenne. Nous montrons comment cette structure peut conduire à une plus grande émission des molécules de colorants ainsi que de centre SiV du diamant. La combinaison du confinement sub-longueur d'onde des LSP et l'énergie élevé des SPP dans notre structure conduit à une focalisation précise qui peut être mis en œuvre pour étudier le couplage plasmon-émetteur dans les régimes de couplage faibles et forts
There is a growing interest nowadays in the study of strong light-matter interaction at the nanoscale, specifically between plasmons and emitters. Researchers in the fields of plasmonics, nanooptics and nanophotonics are constantly exploring new ways to control and enhance surface plasmon launching, propagation, and localization. Moreover, emitters placed in the vicinity of metallic nanoantennas exhibit a fluorescence rate enhancement due to the increase in the electromagnetic field confinement. However, numerous applications such as optical electronics, nanofabrication and sensing devices require a very high optical resolution which is limited by the diffraction limit. Targeting this problem, we introduce a novel plasmonic structure consisting of nanoantennas integrated in the center of ring diffraction gratings. Propagating surface plasmon polaritons (SPPs) are generated by the ring grating and couple with localized surface plasmons (LSPs) at the nanoantennas exciting emitters placed in the gap. We provide a thorough characterization of the optical properties of the simple ring grating structure, the double bowtie nanoantenna, and the integrated ring grating/nanoantenna structure, and study the coupling with an ensemble of molecules as well as single SiV centers in diamond. The combination of the sub-wavelength confinement of LSPs and the high energy of SPPs in our structure leads to precise nanofocusing at the nanoscale, which can be implemented to study plasmon-emitter coupling in the weak and strong coupling regimes
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19

Hou, Xue. "Nano-objets photo-activés pour le ciblage cellulaire et l’hyperthermie." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC011/document.

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Les nanoparticules plasmoniquespossèdent des propriétés intéressantes grâce àla résonance de plasmon de surface localisé. Enplus de leur grande efficacité de conversionphotothermique due au plasmon, leconfinement de l’échauffement peut êtremodulé par le type de source lumineuseutilisée (impulsionnelle ou continue). Cespropriétés font des nanoparticulesplasmoniques une solution potentielle pour lathérapie contre le cancer par hyperthermie.Afin de développer une telle applicationbiomédicale, il est nécessaire d'optimiserl'absorption de l'énergie lumineuse et le ciblagedes nanoparticules sur la tumeur considérée.Dans cette thèse, l'influence des électronschauds photo-générés sur l'absorptiond’impulsions laser ultracourtes par lesnanoparticules est d'abord étudiée. Ensuite, untravail effectué avec des chimistes, biologisteset médecins pour l'application desnanoparticules d’or irradiées par impulsionslaser ultracourtes à la thérapie contre le cancerest présenté. Enfin, nous présentons une étudepréliminaire sur la photoluminescence denanoparticules plasmoniques, dont l'origine estencore controversée, en appliquant un modèleprenant en compte la nature non thermale dela distribution d’électrons chauds
Plasmonic nanoparticles possessinteresting properties thanks to the localizedsurface plasmon resonance. In addition totheir high photothermal conversion efficiency,the heat release confinement can bemodulated by the type of light source used(pulsed or continuous laser). These propertiesmake the plasmonic nanoparticles a potentialsolution for cancer therapy by hyperthermia.In order to develop such a biomedicalapplication, it is necessary to optimize theabsorption of light energy and the targeting ofnanoparticles on the tumor considered.In this thesis, the influence of the photogeneratedhot electrons on the absorption ofultrashort laser pulses by nanoparticles is firststudied. Then, a work carried out withchemists, biologists and physicians for theapplication of gold nanoparticles irradiated byultrashort laser pulses to cancer therapy isdescribed. Finally, we present a preliminarystudy on the photoluminescence of plasmonicnanoparticles, the origin of which is stillcontroversial, by applying a model accountingfor the non-thermal nature of the hot electrondistribution
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Bartholomew, Richard John. "Dynamic plasmonic metasurfaces in the visible spectrum." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/274755.

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As visual display technologies move closer to producing true three dimensional displays, pixel technologies need to be ever smaller and more functional to keep pushing the boundaries. Plasmonic metasurfaces have been shown to control the phase, amplitude and/or polarisation of incoming electromagnetic radiation. Nano-fabrication advancements have resulted in the fabrication of the building blocks of such metasurfaces at nano-scale dimensions, allowing the surfaces to interact with visible light, opening up applications in visual displays. As pixel sizes shrink, smaller colour filters will be required. The excitation of plasmonic resonances in metallic nano-structure arrays have resulted in colour filters an order of magnitude smaller than what is currently commercially available. As colour filters, plasmonic metasurfaces offer numerous advantages over pigment-based colour filters used in modern commercial liquid crystal (LC) displays, including environmental, size and longevity factors. Furthermore, exploiting the wavelength and polarisation dependant scattering of nano-structures, optical components, including lenses, waveplates and holograms containing sub-wavelength pixels have been demonstrated in the visible wavelength spectrum. The metasurfaces are able to mould optical wavefronts into arbitrary shapes with sub-wavelength resolution by introducing spatial variations in the optical response of the light scatterers. The applications demonstrated so far are, on the whole, static devices, that is to say their optical properties may not be altered post fabrication. To realise the full potential of plasmonic metasurfaces to visual applications the devices must be made active. By activating structural colour surfaces, not only may pixel densities potentially be increased simply by removing the need for separate red, green and blue filters, but a new class of high definition ultra-thin display devices may be accessible, whilst the dynamic manipulation of the wavelength and polarisation properties of nano-scattering elements would open up the possibilities to create sub-wavelength holographic pixels. This thesis investigates ways to activate static metasurfaces for colour, flat optic, and holographic applications. First, methods of dynamic control of the structural colour of plasmonic nano-hole arrays are investigated. By combining nano-hole arrays with liquid crystals, transmissive electrically tunable LC-nanohole pixels operating across the visible spectrum with un-polarised input light are experimentally demonstrated. An output analyser in combination with a nematic LC layer enables pixel colour to be electronically controlled through an applied voltage across the device, where LC re-orientation leads to tunable mixing of the relative contributions from the plasmonic colour input. Furthermore, exploiting the strong surface anchoring effects between an aluminium surface and LC molecules a twisted nematic LC cell, using a metallic grating as a combined colour filter, electrode and alignment layer, was shown to act a variable amplitude colour filter. The colour of these pixels was improved greatly utilising a grating-insulator-grating structure unique to this work. Second, a new process for fabricating aluminium nano-rod structures embedded in an elastomeric medium, with high spatial accuracy, is presented. The process is used to create nano-rod plasmonic resonator arrays whose optical properties may be altered by mechanical deformation. The pattern transfer process is further utilised to create dynamic optical elements, including nano-rod arrays for colour filters, tunable focal length Fresnel zone plates and photon sieves, and stretchable holograms with dynamic replay fields.
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Prabhu, G. Radhakrishna. "Studies On Surface Plasmon Resonance And Related Experimental Methods Using Fixed Plasmon Angle." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/205.

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Surface plasmon waves are transverse magnetic electromagnetic waves propagating along a dielectric-metal interface. These waves can be excited by resonant absorption of electromagnetic radiation leading to surface plasmon resonance (SPR) at the interface. The resonance is characterised by a reduction in the intensity of the reflected light at the interface due to strong coupling of incident optical radiation to surface plasmons. This gives rise to a minimum at a sharply defined angle of incidence, referred to as SPR angle or plasmon angle. The phenomenon of SPR has been extensively used in the past to develop reflective type optical devices for sensing applications on account of the high dielectric function dependent sensitivity of the SPR angle. Basically, devices which exhibit this phenomenon have a structure consisting of a metal film sandwiched between two dielectrics. The reflectivity of such a device is theoretically modelled based on either theory of thin films (Fresnel's model) or theory of resonance (Lorentzian model). These models have very effectively predicted the behaviour of such devices based on the shift in SPR angle due to the dielectric function variations. We have been investigating the SPR device for intensity based metrological applications utilising its high angular sensitive reflectivity, with fixed SPR angle. In these intensity based applications or measurements, direct and simple expressions connecting intensity variation to angular change are unavailable in the literature and quantitative estimation or data inversion is based on either curve fitting or iterative methods. Fresnel and Lorentzian models have commonly been used in the experiments but data inversion through the Fresnel model is computationally complex and the Lorentzian model, although less complicated, gives erroneous results due to its approximate nature. In order to obtain a simple expression between intensity variation and the angular change, we have re-looked at the two existing models in order to derive an expression which has the simplicity of the Lorentzian model and the accuracy of the Fresnel model in the experiments with fixed plasmon angles. These efforts have been particularly directed to understand the relationship between intensity variation and meteorologically important properties of such devices. This thesis is an attempt to summarize the computational results which have led us to some novel experimental methodologies which have been used to exploit these devices for inverse type, illumination specific, SPR based applications. The work presented in this thesis is organised in six chapters. Chapter 1, gives an overview of optical sensing, theory of surface plasmons, excitation schemes for surface plasmons, development of the SPR device and its characterisation. It also includes a brief literature review in the area of surface plasmon resonance, covering both the theoretical and experimental aspects. The objectives of the work and the scope of the thesis are also presented. Chapter 2 presents the existing models of SPR device, based on Fresnel's and the Lorentzian models. These models allow reflectance calculations from knowledge of either the optical parameters that describe the layers or the parameters of the waves that propagate through them. Using these models, the inverse problem of estimating either the angle of incidence or the optical constants of the layers of the sensors utilizing the intensity based measurements is generally difficult. In order to solve this problem where the plasmon angles are fixed, a modified formalism for the angle scanned SPR spectrum of a three-layered SPR sensor is presented in this chapter. The new formalism regroups the wave vector parameters of Lorentzian resonance theory into a set of non-dimensional parameters 1, 4K and R. The new reflectivity index (1), which is the ratio of reflectance to the absorptance, has been introduced to help explain the physical processes underlying the device operation in the high sensitivity region of the characteristics. The parameter 4Kis a constant of the device and it depends on the dielectric constants of the device. This is a new SPR index and is identified at a point where reflectance and absorptance match. Parameter R is related to the loss mechanisms in the device and will be explained in detail in Chapter 3. This simple model links the new reflectivity index (1) to the angular detune from SPR angle (ΔƟ) and it brings out a parabolic variation of ΔƟ with 1. In this chapter the mathematical derivation of the proposed model is presented and the significance of the new parameters 1, 4Kand Rare discussed. Chapter 3 evaluates the characteristic nature of errors associated with the predictions from the proposed model and presents methods for neutralizing them. It is demonstrated with the help of the function K which is linearly dependant on 1, that the proposed model predicts the reflectance from the wave vector parameters as accurately as the Fresnel's model. This R parameter explains the slowly varying nature of the radiative loss with the angle of incidence and this variation contributes significantly to the SPR characteristics. As a consequence, it is found that the SPR characteristics can be represented as a sum of two primary functions which are parabolic and linear, respectively, and this leads to the easy explanation of the SPR characteristics. The present chapter also discusses a new observation that the angle-scanned SPR spectrum can be accurately described using a straight line in intercept form. The intercept value depends on 4Kand the slope depends on K. In addition to this, this chapter discusses practical methods for estimation of the intercept and the slope of such a straight line which are functions of the key wave vector parameters. A detailed discussion on the proposed model highlighting its advantages for inverse type, illumination specific, SPR-based applications with fixed SPR angle is also presented. Chapter 4 describes the applications of the proposed model for optical constant measurements. The first part highlights a new approach for the determination of the dielectric constants of the metal film used for the optimised- or nearly-optimised SPR sensors using the proposed model. In the complex dielectric constant, the real part is calculated from the SPR angle and the imaginary part from 4K. A discussion on the dielectric constant study of silver and gold metal film is presented. The advantages of the proposed approach such as its simplicity and direct methodology are then discussed. The second part of the chapter also proposes a new approach to carry out measurements on the absorbance of the medium with enhanced sensitivity utilising the parameter 4K It describes a computational study on the variation of 4K values with the dielectric function and highlights the relationship of 4K variation due to the imaginary part of the dielectric function (absorption) of the samples. The physical processes causing a change in the value of 4Kdue to absorption is also discussed along with some computational results. Chapter 5 reports the study carried out to bring out the importance of the new index,4K in metrological applications. Based on the new model, the effect of the laser beam divergence on SPR curve is studied. This chapter first of all discusses the design of the SPR device and the new methods for the development and characterisation of such a device. Details of the experimental procedure for laser divergence evaluation are proposed along with some of the significant computational results. Furthermore, a few applications such as focal length measurement of optical lenses, micro-displacement measurement based on the divergence of the laser beam are also reported. Since the SPR characteristics can be represented easily using the new model, the angular dependent intensity variation can be utilised for some metrological applications with simple data processing. In this context, the high angular sensitivity of the SPR device is studied and some applications such as micro-displacement measurement, pressure measurement and optical wedge angle measurement are included to highlight the above advantages. The last chapter, Chapter 6, gives a summary and conclusions of the work presented in the thesis. The scope for future investigations is also included in this chapter.
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22

Ajib, Rabih. "Propagation of light in Plasmonic multilayers." Thesis, Université Clermont Auvergne‎ (2017-2020), 2017. http://www.theses.fr/2017CLFAC040/document.

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La plasmonique vise à utiliser des nanostructures métalliques très petites devant la longueur d’onde pour manipuler la lumière. Les structures métalliques sont particulières parce qu’elles contiennent un plasma d’électrons libres qui conditionne complètement leur réponse optique. Notamment, lorsque la lumière se propage à proximité des métaux, sous forme de mode guidés comme les plasmons et les gap-palsmons, elle est souvent lente, présentant une vitesse de groupe faible. Dans ce travail, nous présentons une analyse physique qui permet de comprendre cette faible vitesse en considérant le fait que l’énergie se déplace à l’opposé de la lumière dans les métaux. Nous montrons que la vitesse de groupe est égale à la vitesse de l’énergie pour ces modes guidés, et proposons la notion de ralentissement plasmonique. Finalement, nous étudions comment cette « trainée plasmonique » rend une structure aussi simple qu’un coupleur à prisme sensible à la répulsion entre les électrons du plasma
The field of plasmonics aims at manipulating light using deeply subwavelength nanostructures. Such structures present a peculiar optical response because of the free electron plasma they contain. Actually, when light propagates in the vicinity of metals, usually under the form of a guided mode, it presents a low group velocity. Such modes, like plasmons and gap-plasmons, are said to be slow. In this work we present a general physical analysis of this phenomenon by studying how the energy propagates in metals in a direction that is opposite to the propagation direction of the mode. We show that the group velocity and the energy velocity are the same, and finally introduce the concept of plasmonic drag. Finally, we study how slow guided modes make structures as simple as prism couplers sensitive to the repulsion between electrons inside the plasma
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Rodrigues, Marcos Renan Flores. "Estudo e caracterização de nanopartículas de Fe3O4, Fe2O3, Fe3O4/ Aunanop E Fe2O3/Aunanop." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/184573.

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Nanopartículas de Fe3O4 e Fe2O3 foram sintetizadas a partir da rota de coprecipitação, em atmosfera de N2, mantendo-se o pH entre 9 e 14 na temperatura ambiente e utilizando como precursores o FeCl2 e FeCl3. Após a síntese, as nanopartículas foram tratadas termicamente a 250, 500 e 800 oC. Para obtenção de um sistema híbrido, foram sintetizadas nanopartículas de ouro sobre as nanopartículas de óxido previamente tratadas em diferentes temperaturas. As amostras foram caracterizadas por UV-Vis, difratometria de Raios-X (DRX), microscopia eletrônica de transmissão (MET), microscopia eletrônica de transmissão de alta resolução (MET-AR), espectroscopia no na região do infravermelho (FTIR), magnometria de amostra vibrante (VSM) e espectroscopia Mossbauer (EM), e aplicadas para produção de hidrogênio promovendo a decomposição da hidrazina. Os resultados mostram a síntese de nanopartículas de óxido de ferro com diâmetro médio de cerca de 7 nm. Quando aquecidas a 250 oC o tamanho médio aumentou para ca. de 11 nm e foi observado uma pequena mudança no comportamento óptico e estrutural, mantendo o comportamento superparamagnetico. Quando aquecidas a 500 oC o tamanho médio aumenta para ca. de 50nm e são observadas mudanças significativas nas propriedades ópticas, morfológicas, estruturais. Adicionalmente observa-se transição de comportamento superparamagnetico para paramagnético. Quando aquecidas a 800 oC os efeitos nas propriedades dos materiais são ainda mais significativos; as partículas apresentam tamanho médio de 200 nm, o espectro de absorção no UV-Vis muda significativamente e as partículas passam a ter comportamento pagamagnético. Os resultados obtidos pelas diferentes técnicas e somadas ao Mossbauer sugerem que as amostras sintetizadas são uma mistura de Fe3O4 e -Fe2O3, quando aquecido a 250 e 500 oC uma mistura de -Fe2O3 e -Fe2O3 e a 800 oC somente -Fe2O3. As nanopartículas de ouro sintetizadas sobre as amostras de oxido de ferro apresentaram tamanho médio de 6,0 nm e não afetaram as propriedades magnéticas dos oxidos. As amostras de óxido com nanopartículas de ouro promoveram a decomposição da hidrazina por rota completa, levando a formação de hidrogênio com seletividade de até 33%.
Fe3O4 and Fe2O3 nanoparticles were synthesized by coprecipitation route carried out under N2 atmosphere, maintaining the pH between 9 and 14 at room temperature and using FeCl2 and FeCl3 as precursors. After synthesis the iron oxide nanoparticles were thermally treated at 250, 500 and 800 oC. To obtain a hybrid system, gold nanoparticles were synthesized on the thermally treated oxide nanoparticles. The samples were analyzed by UV-Vis, X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (MET-AR), spectroscopy in the region of Infrared (FTIR), vibrating sample magnitude (VSM) and Mossbauer, and applied to produce H2 through hydrazine decomposition. The results show the synthesis of Fe3O4 nanoparticles with average diameter of about 7 nm. When heated to 250 oC the average size increased to about 11 nm and a small change in the optical and structural behavior was observed, while the superparamegnetic behaviour was maintained. When heated to 500 °C, the average particle size increase to ca 51nm, significant changes in the optical, morphological and structural properties are observed, in addition to a transition from superparamegnetic to paramagnetic behaviour. When heated to 800 oC the effects on the properties are even more significant; the nanoparticles increase to ca. 200 nm, the absorption spectrum in UV-Vis changes significantly and the particles present paramagnetic behaviour. The results suggest that when heated to 250 and 500 oC a mixture of -Fe2O3 e -Fe2O3 is obtained, after heating at 800 oC only -Fe2O3 is observed. The gold nanoparticles synthesized on the iron oxides present average size of 6.0 nm, and did not affect the magnetic properties of the oxides. The iron oxides/gold nanoparticle samples were efficiently applied to produce hydrogen, promoting the decomposition of hydrazin. The selectivity to hydrogen reached up to 33%.
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24

Kvapil, Michal. "Lokalizované povrchové plazmony: principy a aplikace." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229109.

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The diploma thesis deals with plasmonic nanostructures for visible eventually near-infrared region of electromagnetic spectrum. At first, there are discussed basic terms which are necessary for description of plasmonic nanostructures and their properties. Then the resonant properties of gold nanoantennas on a fused silica substrate and in proximity of nanocrystalline diamond are addressed. FDTD simulations are used for an assesment of resonant properties and local electric field enhancement of these nanostructures. Possible manufacturing methods of the antennas and techniques for the measurement of their properties are mentioned at the end of the thesis.
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25

Wang, Tao. "Excitation électrique de plasmons de surface avec un microscope à effet tunnel." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00868784.

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Pour la première fois, en associant un microscope à effet tunnel (STM) et un microscope optique inversé,nous avons imagé les plasmons de surface excités électriquement sur un film d'or avec la pointe d'un STM.Par microscopie de fuite radiative, en observant l'image de l'interface air/or et celle du plan de Fourierassocié, nous avons distingué les plasmons propagatifs des plasmons localisés sous la pointe. Les plasmonspropagatifs sont caractérisés par une distance de propagation et une direction d'émission en accord aveccelles de plasmons propagatifs créés par excitation laser sur des films d'or de mêmes épaisseurs. Les fuitesradiatives des plasmons localisés s'étalent jusqu'à l'angle maximum d'observation. Plasmons propagatifs etlocalisés ont une large bande spectrale dans le visible. Si la pointe est plasmonique (en argent), lesplasmons localisés ont une composante supplémentaire due au couplage associé. Pour différents types depointe, nous avons déterminé les intensités relatives des plasmons localisés et propagatifs. Nous trouvonsque chaque mode plasmon (propagatif ou localisé) peut être préférentiellement sélectionné en modifiant lematériau de la pointe et sa forme. Une pointe en argent produit une intensité élevée de plasmons localisés,tandis qu'une pointe fine de tungstène (rayon de l'apex inférieur à 100 nm) produit essentiellement desplasmons propagatifs. Nous avons étudié la cohérence spatiale des plasmons propagatifs excités par la pointe du STM. Avec un film d'or opaque (épaisseur 200 nm) percé de paires de nanotrous nous avons réalisé une expérienceanalogue à celle des fentes d'Young. Des franges d'interférences sont observées. La mesure de leurvisibilité en fonction de la distance des nanotrous donne une longueur de cohérence des plasmons de 4.7±0.5 μm. Cette valeur, très proche de la valeur 3.7± 1.2 μm déduite de la largeur de la distribution spectraledes plasmons, indique que l'élargissement spectral des plasmons propagatifs est homogène.Nous avons aussi étudié la diffusion des plasmons propagatifs excités par la pointe du STM par desnanoparticules d'or déposées sur un film d'épaisseur 50 nm. Nous observons une diffusion élastique et unediffusion radiative. Des franges d'interférences sont observées dans la région d'émission lumineuseinterdite du plan de Fourier, dont la période est inversement proportionnelle à la distancepointe-nanoparticule d'or avec un facteur de proportionnalité égal à la longueur d'onde moyenne desplasmons. Il y a donc interférence entre la radiation des plasmons localisés et la radiation provenant de ladiffusion des plasmons propagatifs sur les nanoparticules d'or. Ceci indique que les plasmons localisés etpropagatifs excités électriquement par la pointe du STM sont différentes composantes du plasmon uniqueproduit par effet tunnel inélastique avec la pointe du STM. Ces résultats originaux sur les plasmons créés sur film d'or par un effet tunnel inélastique localisé à l'échelle atomique (i) élargissent la compréhension du processus et (ii) offrent des perspectives intéressantes pour une association de la nanoélectronique et de la nanophotonique.
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26

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.
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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27

Lange, Philipp. "Optical and structural properties of systems of conjugated molecules and graphenes." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://dx.doi.org/10.18452/16938.

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Systeme aus konjugierten Molekülen und Graphenen bergen hohes Potential für Anwendungen. Die Untersuchung ihrer Wechselwirkungsmechanismen ist wichtig für die Entwicklung neuer Anwendungen und Fokus dieser Arbeit: Optische Mikroskopie, Spektroskopie und Rasterkraftmikroskopie werden komplementär verwendet, um die optischen und strukturellen Eigenschaften solcher Systeme zu erforschen. Insbesondere werden (i) die Permeationsbarriere-Eigenschaften von Graphen in-situ auf einem halbleitenden Polymerfilm quantifiziert. Weiterhin werden (ii) die Fluoreszenz- und (iii) Raman-Emission von konjugierten Molekülen in der Nähe von Graphen untersucht und die entsprechenden Kopplungsmechanismen diskutiert. (i) Graphene zeigen sich als effizienter Schutz des empfindlichen Polymers [Poly(3-hexylthiophen)] vor Degeneration durch Sauerstoff und Wasser aus der Umgebungsluft. Dies legt nahe, dass Graphene nicht nur als transparente Elektrode, sondern gleichzeitig als Barriereschicht in künftigen optoelektronischen Bauelementen dienen können. (ii) Es wird gezeigt, dass die bekannten optischen Eigenschaften von Graphen die Existenz stark lokalisierter Graphen-Plasmonen im Sichtbaren implizieren. Durch Verwendung von nanoskaligen Emittern [Rhodamin 6G (R6G)], welche die für effiziente Anregung von Graphen-Plasmonen im optischen Frequenzbereich notwendigen großen Wellenvektor bereitstellen, wird Graphen-Plasmonen-induzierte (GPI) Fluoreszenz-Anregungsverstärkung von nahezu 3 Größenordnungen nachgewiesen. Demnach ist Graphen für plasmonische Bauelemente im Sichtbaren interessant. (iii) Außerdem wird GPI Verstärkung des Raman-Querschnittes von R6G um 1 Größenordnung nachgewiesen. Zukünftige Entwicklung von Antennen für zusätzliche direkte Anregung von Graphen-Plasmonen aus dem Fernfeld macht Graphen vielversprechend für leistungsfähige oberflächenverstärkte Raman-Spektroskopie. Zusammenfassend wurden neue und anwendungsrelevante Einblicke in die analysierten Systeme gewonnen.
Systems of conjugated molecules and graphenes bear high application potential. The investigation of their interaction mechanisms is important for design of new applications and the focus of this thesis: Optical microscopy, spectroscopy and scanning force microscopy are complementarily used to explore the optical and structural properties of such systems. In particular (i) the permeation barrier properties of graphene are quantified in-situ on a semiconducting polymer film. Furthermore (ii) the fluorescence and (iii) Raman emission of conjugated molecules in proximity to graphene are investigated and the respective coupling mechanisms are discussed. (i) Graphenes are found to efficiently protect the sensitive polymer [poly(3-hexylthiophene)] from degradation by oxygen and water from the ambient atmosphere. This suggests that graphenes can not only serve as transparent electrode, but simultaneously as a barrier layer in future optoelectronic devices. (ii) It is shown that the known optical properties of graphene imply the existence of strongly localized graphene plasmons in the visible. Using nanoscale emitters [rhodamine 6G (R6G)] that provide the high wave vectors necessary to efficiently excite graphene plasmons at optical frequencies, graphene plasmon induced (GPI) fluorescence excitation enhancement by nearly 3 orders of magnitude is demonstrated. Graphene is thus interesting for plasmonic devices in the visible. (iii) In addition GPI enhancement of the Raman cross section of R6G by 1 order of magnitude is demonstrated. The future design of antennas for additional direct farfield excitation of graphene plasmons makes graphene promising for powerful surface enhanced Raman spectroscopy. In summary new and application relevant insights were gained into the studied systems.
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28

Olk, Phillip. "Optical Properties of Individual Nano-Sized Gold Particle Pairs." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1218612352686-00553.

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This thesis examines and exploits the optical properties of pairs of MNPs. Pairs of MNPs offer two further parameters not existent at single MNPs, which both affect the local optical fields in their vicinity: the distance between them, and their relative orientation with respect to the polarisation of the excitation light. These properties are subject of three chapters: One section examines the distance-dependent and orientation-sensitive scattering cross section (SCS) of two equally sized MNPs. Both near- and far-field interactions affect the spectral position and spectral width of the SCS. Far-field coupling affects the SCS even in such a way that a two-particle system may show both a blue- and redshifted SCS, depending only on the distance between the two MNPs. The maximum distance for this effect is the coherence length of the illumination source – a fact of importance for SCS-based experiments using laser sources. Another part of this thesis examines the near-field between two MNPs and the dependence of the locally enhanced field on the relative particle orientation with respect to the polarisation of the excitation light. To attain a figure of merit, the intensity of fluorescence light from dye molecules in the surrounding medium was measured at various directions of polarisation. The field enhancement was turned into fluorescence enhancement, even providing a means for sensing the presence of very small MNPs of 12 nm in diameter. In order to quantify the near-field experimentally, a different technique is devised in a third section of this thesis – scanning particle-enhanced Raman microscopy (SPRM). This device comprises a scanning probe carrying an MNP which in turn is coated with a molecule of known Raman signature. By manoeuvring this outfit MNP into the vicinity of an illuminated second MNP and by measuring the Raman signal intensity, a spatial mapping of the field enhancement was possible
Diese Dissertation untersucht und nutzt die optischen Eigenschaften von Paaren von Metall-Nanopartikeln (MNP). MNP-Paare bieten gegenüber einzelnen MNP zwei weitere Parameter, welche beide auf das optische Nahfeld der zwei MNPs wirken: zum Einen der Abstand der zwei MNPs zueinander, zum Anderen die relative Ausrichtung des Paares bezüglich der Polarisation des anregenden Lichts. Diese Eigenschaften sind Thema der Arbeit: Ein Abschnitt untersucht den abstands- und orientierungsabhängigen Streuquerschnitt (SQS) zweier gleichgroßer MNPs. Die spektrale Position und die Breite des SQS wird von Wechselwirkungen sowohl im Nah- als auch im Fernfeld beeinflusst. Der Einfluß der Fernfeld-Wechselwirkung geht so weit, daß ein Zwei-MNP-System sowohl einen blau- als auch einen rotverschobenen SQS haben kann – dies hängt lediglich vom Abstand der zwei MNPs ab. Die Reichweite dieser Fernfeld-Wechselwirkung wird durch die Kohärenzlänge der Beleuchtungsquelle bestimmt – eine wichtige Tatsache für SQS-Untersuchungen, welche Laserquellen verwenden. Ein weiterer Teil der Dissertation untersucht das Nahfeld zwischen zwei MNPs. Insbesondere wird dargestellt, inwieweit die Überhöhung des Nahfelds von der Orientierung des Partikelpaares bezüglich der Polarisation des Anregungslichts abhängt. Um den Effekt quantifizieren zu können, wurde die Intensität der Fluoreszenz des umgebenden Mediums für verschiedene Polarisationsrichtungen gemessen. Die lokale Feldverstärkung konnte in eine Fluoreszenzverstärkung gewandelt werden, mit deren Hilfe sich sogar die Anwesenheit sehr kleiner MNPs von nur 12 nm Durchmesser nachweisen ließ. Wie Nahfeld-Intensitäten experimentell quantifiziert werden können, stellt ein dritter Abschnitt dieser Dissertation vor – per MNP-verstärkter Raman-Rastersonden-Mikroskopie. Diese Technik besteht aus einer Rastersonde, welcher ein MNP anheftet, welches wiederum mit einem Molekül bekannter Ramansignatur überzogen ist. Indem solch eine Sonde in die unmittelbare Nähe eines zweiten, beleuchteten MNPs gebracht wurde und dabei die Intensität des Raman-Signals aufgezeichnet wurde, ließ sich die räumliche Verteilung der Ramanverstärkung vermessen
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29

Habert, Benjamin. "Contrôle de la fluorescence par des nanoantennes plasmoniques." Phd thesis, Palaiseau, Institut d'optique théorique et appliquée, 2014. http://pastel.archives-ouvertes.fr/pastel-01023199.

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Dans ce travail de these, nous étudions comment des nano-structures métalliques modifient le processus d'émission spontannée d'objets fluorescents et jouent ainsi un rôle d'antenne. Ces structures supportent des modes optiques confinés aux interfaces metal-diélectrique: ce sont des modes plasmoniques.De par leur fort confinement, ces modes modifient la densité locale d'états optiques et permettent notamment d'accélérer le processus d'émission spontannée (facteur de Purcell). Nous étudions le cas d'une structure planaire metal-isolant-métal de type patch couplée à un ensemble de nanocristaux colloïdaux fluorescents. Nos mesures, soutenues par des calculs numériques, montrent une acceleration de l'émission fluorescente d'un facteur 80 ainsi qu'une augmentation de la directivité de l'émission. Nous décrivons ensuite le procedé de fabrication d'une structure patch metal-semiconducteur-métal pour laquelle la source fluorescente est un puits quantique émettant dans le proche infra-rouge. Nous montrons que l'antenne permet d'augmenter l'extraction fluorescente d'un facteur 8. Enfin, nous considérons le cas d'une structure sphérique composée d'un unique nanocristal fluorescent au centre d'une bille de silice entourée par une fine coquille métallique. Cette structure plasmonique accélère l'émission d'une facteur 10 et permet de supprimer le scintillement caractéristique de l'émission des nanocristaux. La coquille métallique permet également d'isoler chimiquement le nanocristal de l'environnement, assurant ainsi une grande photostabilité et une toxicité réduite. L'émetteur ainsi obtenu est donc un candidat prometteur pour des applications de marquage de fluorescence in-vivo.
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30

Schira, Romain. "Réponse optique d’agrégats d’argent : excitations plasmoniques et effets de l’environnement." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1162/document.

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Les réponses optiques d'agrégats de métaux nobles sont caractérisées par une absorption intense, situées dans le domaine UV-Visible, et appelée plasmon de surface localisé. Pour des particules de plusieurs nanomètres de diamètre, le phénomène de plasmon peut être interprété par des modèles semi-classiques ou classiques comme la théorie de Mie, mais ces modèles trouvent leur limite lorsque la taille du système diminue. La théorie de la fonctionnelle de la densité dépendante du temps (TDDFT) est une approche entièrement quantique qui permet d'appréhender le phénomène de plasmon en reproduisant la réponse optique de petits agrégats d'argent, composés de quelques atomes à quelques centaines d'atomes. Dans ce contexte, nous avons réalisé des calculs TDDFT avec une fonctionnelle de type Range-Separated-Hybrid (RSH) sur des agrégats contenant entre 8 et 147 atomes d'argent. Les spectres obtenus sont en excellent accord avec les données expérimentales et les réponses optiques calculées perme ttent de retrouver les prédictions du modèle en couches. Nous présentons des outils permettant d'identifier et de caractériser les excitations plasmoniques dans le formalisme de la TDDFT. Les effets de l'environnement sur la réponse optique des agrégats sont également étudiés, avec notamment la présentation d'une méthodologie permettant de reproduire les spectres mesurés sur des agrégats d'argent piégés dans des matrices de gaz rare. Les effets de l'oxydation et les effets induits par une matrice de silice sur la réponse optique des agrégats sont également étudiés
Optical responses of noble metal clusters are characterized by a strong absorption in the UV-Visible range called localized surface plasmon. For clusters of several nanometers, the plasmon phenomenon can be interpreted by semi-classical or classical model, as the Mie theory, but those models can not describe the optical response of small-size clusters. The time dependent density functional theory (TDDFT) is a quantum method that allow to understand the plasmon phenomenon by reproducing the optical response of small silver cluster, made of a few tens or hundreds atoms. In this context, we performed TDDFT calculation using Range-Separated Hybrid (RSH) functionals over cluster containing between 8 and 147 silver atoms. The obtained spectra are in excellent agreement with the experimental ones and the calculated optical response allows to recover the shell model prediction. We present some tools that allow to identify and characterize plasmonic excitations within the TDDFT framework. The effect of the surrounding medium over the optical response of clusters are studied, in particular we will present a methodology that allow to reproduce spectra measured over clusters trapped in rare gas matrix. The effects of the oxidation and the effects induced by a silica matrix over the optical response of clusters are also studied
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31

Cleary, Justin. "Surface Plasmon Hosts for Infrared Waveguides and Biosensors, and Plasmons in Gold-Black Nano-Structured Films." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3562.

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Applications of surface plasmon polaritons (SPPs) have thus far emphasized visible and near-infrared wavelengths. Extension into the long-wave infrared (LWIR) has numerous potential advantages for biosensors and waveguides, which are explored in this work. A surface plasmon resonance (SPR) biosensor that operates deep into the infrared (3-11 µm wavelengths) is potentially capable of biomolecule recognition based on both selective binding and characteristic vibrational modes. The goal is to operate such sensors at wavelengths where biological analytes are strongly differentiated by their IR absorption spectra and where the refractive index is increased by dispersion, which will provide enhanced selectivity and sensitivity. Potentially useful IR surface plasmon resonances are investigated on lamellar gratings formed from various materials with plasma frequencies in the IR wavelength range including doped semiconductors, semimetals, and conducting polymers. One outcome of this work has been the demonstration of a simple analytic formula for calculating the SPP absorption resonances in the angular reflectance spectra of gratings. It is demonstrated for Ag lamellar gratings in the 6-11 µm wavelength range. The recipe is semi-empirical, requiring knowledge of a surface-impedance modulation amplitude, which is found here by comparison to experiment as a function of the grating groove depth and the wavelength. The optimum groove depth for photon-to-SPP energy conversion was found by experiment and calculation to be ~10-15% of the wavelength. Hemicylindrical prism couplers formed from Si or Ge were investigated as IR surface plasmon couplers for the biosensor application. Strong Fabry-Perot oscillations in the angular reflectance spectra for these high index materials suggest that grating couplers will be more effective for this application in the LWIR. A variety of materials having IR plasma frequencies were investigated due to the tighter SPP mode confinement anticipated in the IR than for traditional noble metals. First doped-Si and metal silicides (Ni, Pd, Pt and Ti) were investigated due to their inherent CMOS compatibility. Rutherford backscattering spectroscopy, x-ray diffraction, scanning electron microscopy, secondary ion mass spectrometry and four point probe measurements complemented the optical characterization by ellipsometry. Calculation of propagation length and mode confinement from measured permittivities demonstrated the suitability for these materials for LWIR SPP applications. Semimetals were also investigated since their plasma frequencies are intermediate between those of doped silicon and metal silicides. The semimetal antimony, with a plasma frequency ~80 times less than that of gold was characterized. Relevant IR surface plasmon properties, including the propagation length and penetration depths for SPP fields, were determined from optical constants measured in the LWIR. Distinct resonances due to SPP generation were observed in angular reflection spectra of Sb lamellar gratings in the wavelength range of 6 to 11 µm. Though the real part of the permittivity is positive in this range, which violates the usual condition for the existence of bound SPP modes, calculations based on experimental permittivity showed that there is little to distinguish bound from unbound SPP modes for this material. The SPP mode decays exponentially away from the surface on both sides of the permittivity sign change. Water is found to broaden the IR plasmon resonances significantly at 9.25 micron wavelength where aqueous extinction is large. Much sharper resonances for water based IR SPR biosensor can be achieved in the 3.5 to 5.5 µm range. Nano-structured Au films (Au-black) were investigated as IR absorbers and possible solar cell enhancers based on surface plasmon resonance. The characteristic length scales of the structured films vary considerably as a function of deposition parameters, but the absorbance is found to be only weakly correlated with these distributions. Structured Au-black with a broad range of cluster length scales appear to be able to support multiple SPP modes with incident light coupling to the corrugated surface as seen by photoelectron emission microscopy (PEEM) and SPR experiments, supporting the hypothesis that Au-black may be a suitable material for plasmon-resonance enhancement solar-cell efficiency over the broad solar spectrum.
Ph.D.
Department of Physics
Sciences
Physics PhD
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32

Chamtouri, Maha. "Etude exhaustive de la sensibilité des Biopuces plasmoniques structurées intégrant un réseau rectangulaire 1D : effet de la transition des plasmons localisés vers les plasmons propagatifs." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112060/document.

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Malgré leurs contribution dans plusieurs domaines, les biopuces à lecture plasmonique conventionnelles basées sur l'utilisation d’un film métallique plan d'or, sont limitées en terme de sensibilité surtout quand il s'agit de détecter des molécules de faible masse molaire à l’état de trace.Dans ce cadre, nous étudions numériquement et expérimentalement le potentiel de détection d’interactions biomoléculaires d’une nouvelle génération de biopuces à lecture plasmonique intégrant un film métallique micro-nano-structurée en réseau rectangulaire 1D. L’étude numérique développée met en œuvre une méthode hybride, basée sur la combinaison de deux méthodes classiques : la méthode des éléments finis et la méthode modale de Fourier. Grâce à ce nouvel outil numérique, nous présentons une cartographie exhaustive du potentiel de détection d’une couche biologique, en variant les paramètres de la structuration liés aux dimensions du réseau. La réponse de la biopuce à l’accrochage de biomolécules est ensuite interprétée théoriquement par les différents phénomènes plasmoniques notamment les «points chauds» et les bandes plasmoniques interdites. Nos calculs soulignent l'importance de l’exploitation du confinement de la lumière à travers la structuration sub-longueur d’onde des surfaces plasmoniques. Ceci permet non seulement d’optimiser les paramètres géométriques afin d’améliorer la sensibilité vis-à-vis de la réponse d’une biopuce conventionnelle, mais aussi de mettre en évidence la transition entre le régime où les plasmons propagatifs dominent et le régime où les plasmons localisés dominent. De nouvelles figures de mérite sont introduites pour évaluer les performances des biopuces structurées.Cette étude montre également que de nouvelles opportunités pour améliorer davantage la bio-sensibilité sont offertes, si la localisation de biomolécules peut être effectuée dans les régions où le champ électrique est amplifié et confiné
Surface plasmons resonance imaging with continuous thin metallic films have become a central tool for the study of biomolecular interactions. However, in order to extend the field of applications of surface plasmons resonance systems to the trace detection of biomolecules having low molecular weight, a change in the plasmonic sensing methodology is needed. In this study, we investigate theoretically and experimentally the sensing potential of 2D nano- and micro- ribbon grating structuration on the surface of Kretschmann-based surface plasmon resonance biosensors when they are used for detection of biomolecular binding events. Numerical simulations were carried out by employing a fast and novel model based on the hybridization of two classical methods, the Fourier Modal Method and the Finite Element Method. Our calculations confirm the importance of light manipulation by means of structuration of the plasmonic thin film surfaces on the nano- and micro- scales. Not only does it highlight the geometric parameters that allow the sensitivity enhancement, and associated figures of merit, compared with the response of the conventional surface plasmon resonance biosensor based on a flat surface, but it also describes the transition from the regime where the propagating surface plasmon mode dominates to the regime where the localized surface plasmon mode dominates. An exhaustive mapping of the biosensing potential of the nano- and micro- structured biosensors surface is presented, varying the structural parameters related to the ribbon grating dimensions. New figures of merit are introduced to evaluate the performance of the structured biosensors. The structuration also leads to the creation of regions on biosensor chips that are characterized by strongly enhanced electromagnetic fields. New opportunities for further improving the bio-sensitivity are offered if localization of biomolecules can be carried out in these regions of high electromagnetic fields enhancement and confined
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33

Durach, Maxim. "Giant Plasmonic Energy and Momentum Transfer on the Nanoscale." Digital Archive @ GSU, 2009. http://digitalarchive.gsu.edu/phy_astr_diss/42.

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We have developed a general theory of the plasmonic enhancement of many-body phenomena resulting in a closed expression for the surface plasmon-dressed Coulomb interaction. It is shown that this interaction has a resonant nature. We have also demonstrated that renormalized interaction is a long-ranged interaction whose intensity is considerably increased compared to bare Coulomb interaction over the entire region near the plasmonic nanostructure. We illustrate this theory by re-deriving the mirror charge potential near a metal sphere as well as the quasistatic potential behind the so-called perfect lens at the surface plasmon (SP) frequency. The dressed interaction for an important example of a metal–dielectric nanoshell is also explicitly calculated and analyzed. The renormalization and plasmonic enhancement of the Coulomb interaction is a universal effect, which affects a wide range of many-body phenomena in the vicinity of metal nanostructures: chemical reactions, scattering between charge carriers, exciton formation, Auger recombination, carrier multiplication, etc. We have described the nanoplasmonic-enhanced Förster resonant energy transfer (FRET) between quantum dots near a metal nanoshell. It is shown that this process is very efficient near high-aspect-ratio nanoshells. We have also obtained a general expression for the force exerted by an electromagnetic field on an extended polarizable object. This expression is applicable to a wide range of situations important for nanotechnology. Most importantly, this result is of fundamental importance for processes involving interaction of nanoplasmonic fields with metal electrons. Using the obtained expression for the force, we have described a giant surface-plasmoninduced drag-effect rectification (SPIDER), which exists under conditions of the extreme nanoplasmonic confinement. Under realistic conditions in nanowires, this giant SPIDER generates rectified THz potential differences up to 10 V and extremely strong electric fields up to 10^5-10^6 V/cm. It can serve as a powerful nanoscale source of THz radiation. The giant SPIDER opens up a new field of ultraintense THz nanooptics with wide potential applications in nanotechnology and nanoscience, including microelectronics, nanoplasmonics, and biomedicine. Additionally, the SPIDER is an ultrafast effect whose bandwidth for nanometric wires is 20 THz, which allows for detection of femtosecond pulses on the nanoscale.
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34

Biesso, Arianna. "Plasmonic field effects on the spectroscopic and photobiological function of the photosynthetic system of bacteriorhodopsin." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/28162.

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Thesis (M. S.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009.
Committee Chair: Mostafa A. El-Sayed; Committee Member: Adegboyega K. Oyelere; Committee Member: Bridgette Barry; Committee Member: Joseph W. Perry; Committee Member: Mark R. Prausnitz.
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35

Hajebifard, Akram. "Plasmonic Nano-Resonators and Fano Resonances for Sensing Applications." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/41616.

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Different types of plasmonic nanostructures are proposed and examined experimentally and theoretically, with a view towards sensing applications. First, a self-assembly approach was developed to create arrays of well-ordered glass-supported gold nanoparticles (AuNPs) with controllable particle size and inter-particle spacing. Then, a periodic array of gold nano-disks (AuNDs) supported by a Bragg reflector was proposed and examined in a search for Fano resonances in its optical response. Arrays of heptamer-arranged nanoholes (HNH) in a thin gold film were also proposed and explored theoretically and experimentally, revealing a very rich spectrum of resonances, several exhibiting a Fano lineshape. A commercial implementation of the vectorial finite element method (FEM) was used to model our plasmonic structures. Taking advantage of the periodic nature of the structures, a unit cell containing a single element was modelled. The transmittance, reflectance or absorbance spectra were computed, and the associated electromagnetic fields were obtained by solving the vector wave equations for the electromagnetic field vectors throughout the structures, subject to the applicable boundary conditions, and the applied source fields. The sensing performance of the structures, based on the bulk sensitivity, surface sensitivity and figure of merit (FOM) was calculated. First, a novel bottom-up fabrication approach was applied (by our collaborators) to form a periodic array of AuNPs with controllable size over large areas on SiO2 substrates. In this method, self-assembly of block copolymer micelles loaded with metal precursors was combined with a seeding growth route to create ordered AuNPs of desired size. It was shown that this new fabrication method offers a new approach to tune the AuNP size and edge-to-edge inter-particle spacing while preserving the AuNP ordering. The optical characteristics of the AuNP arrays, such as their size, interparticle spacing, localized surface plasmon resonance (LSPR) wavelength, and bulk sensitivity, were examined, numerically and experimentally. This proposed novel fabrication method is applicable for low-cost mass-production of large-area arrays of high-quality AuNPs on a substrate for sensing applications. Then, we proposed and examined the formation of Fano resonances in a plasmonic-dielectric system consisting of uncoupled gold nano-disk (AuND) arrays on a quarter-wave dielectric stack. The mechanism behind the creation of Fano resonances was explained based on the coherent interference between the reflection of the Bragg stack and the LSPPs of the AuNDs. Fano parameters were obtained by fitting the computational data to the Fano formula. The bulk sensitivities and figure of merit of the Fano resonances were calculated. This plasmonic structure supports Fano resonances with a linewidth around 9 nm which is much narrower than the individual AuND LSPP bandwidth ( 80 nm) and the Bragg stack bandwidth ( 100 nm). Supporting Fano resonances with such a narrow linewidth, the structure has a great potential to be used for sensing applications. Also, this metallic-dielectric nanostructure requires no near-field coupling between AuNDs to generate the Fano resonances. So, the AuNDs can be located far enough from each other to simplify the potential fabrication process. The optical properties of HNH arrays on an SiO2 substrate were investigated, numerically and experimentally. Helium focused ion beam (HeFIB) milling was applied (by Dr. Choloong Hahn) to fabricate well-ordered and well-defined arrays of HNHs. Transmittance spectra of the structures were obtained as the optical response, which exhibits several Fano resonances. Then, the mechanism behind the formation of the Fano resonances was explained, and the sensing performance of the structure was inspected by measuring the bulk sensitivities. This array of nanohole cluster is exciting because it supports propagating SPPs and LSPPs, and also Wood’s anomaly waves, which makes the optical response very rich in excitations and spectral features. Also, as a periodic array of sub-wavelength metallic nanoholes, the system produces extraordinary optical transmission - highly enhanced transmission through (otherwise) opaque metallic films at specific wavelengths, facilitating measurement acquisition in transmission.
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36

Vemuri, Padma Rekha. "Surface Plasmon Based Nanophotonic Optical Emitters." Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc5584/.

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Group- III nitride based semiconductors have emerged as the leading material for short wavelength optoelectronic devices. The InGaN alloy system forms a continuous and direct bandgap semiconductor spanning ultraviolet (UV) to blue/green wavelengths. An ideal and highly efficient light-emitting device can be designed by enhancing the spontaneous emission rate. This thesis deals with the design and fabrication of a visible light-emitting device using GaN/InGaN single quantum well (SQW) system with enhanced spontaneous emission. To increase the emission efficiency, layers of different metals, usually noble metals like silver, gold and aluminum are deposited on GaN/InGaN SQWs using metal evaporator. Surface characterization of metal-coated GaN/InGaN SQW samples was carried out using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Photoluminescence is used as a tool for optical characterization to study the enhancement in the light emitting structures. This thesis also compares characteristics of different metals on GaN/InGaN SQW system thus allowing selection of the most appropriate material for a particular application. It was found out that photons from the light emitter couple more to the surface plasmons if the bandgap of former is close to the surface plasmon resonant energy of particular metal. Absorption of light due to gold reduces the effective mean path of light emitted from the light emitter and hence quenches the quantum well emission peak compared to the uncoated sample.
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37

Goffard, Julie. "Etude du couplage entre des nanocristaux de silicium et des plasmons de surface localisés." Thesis, Troyes, 2014. http://www.theses.fr/2014TROY0012/document.

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La découverte de la photoluminescence du silicium sous sa forme nanométrique a ouvert la voie de l’utilisation du silicium dans les composants optoélectroniques. Cependant cette photoluminescence reste trop peu efficace et de nombreuses recherches portent aujourd’hui sur l’amélioration des propriétés optiques du silicium. Ce travail de thèse s’intéresse particulièrement à l’utilisation de plasmons de surface localisés afin d’améliorer les propriétés optiques de nanocristaux de silicium. Grâce au contrôle de tous les paramètres géométriques des nanocristaux de silicium et des nanoparticules métalliques lors de la fabrication des échantillons, il a été possible d’étudier les phénomènes physiques du couplage entre ces deux objets. Une modification de l’émission des nanocristaux de silicium en fonction de la distance, de la taille et de la nature des nanoparticules métalliques a été étudiée. Grâce au développement de différentes techniques de caractérisation optique, il a été possible de montrer que la photoluminescence des nanocristaux de silicium était modifiée à la fois spectralement et spatialement par les plasmons de surface localisés. Ce travail montre que grâce aux plasmons de surface localisés il est possible de grandement améliorer la photoluminescence des nanocristaux de silicium et ainsi il est possible d’imaginer de nouveaux composants optoélectroniques à base de silicium et de plasmons
The discovery of photoluminescence of nanometric silicon paves the way to use silicon in optoelectronic devices. However this photoluminescence remains low and a lot of works aim at improving silicon optical properties. In this dissertation we study localized surface plasmons to improve optical properties of silicon nanocrystals. Thanks to the control of all geometrical parameters of silicon nanocrystals and metallic nanoparticles during the fabrication process, the coupling process between these two objects has been studied. The modification of silicon nanocrystals emission as a function of the distance, the size and the nature of metallic nanoparticles has been investigated. Thanks to the development of experimental optical characterization techniques we showed that silicon nanocrystals photoluminescence is modified both spectrally and spatially by localized surface plasmons. This work shows that it’s possible to enhance silicon’s optical properties and thus to devise optoelectronic devices with silicon and plasmons
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38

Derom, Stephane. "Plasmonic cavities and optical nanosources." Thesis, Dijon, 2013. http://www.theses.fr/2013DIJOS060/document.

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Les microcavités optiques présentent de hauts facteurs de qualité, c'est pourquoi ces systèmes sont d'un grand intérêt pour la conception de lasers à bas seuil, ou encore, pour l'étude du régime de couplage fort. En revanche, ces systèmes sont soumis à la limite de diffraction de la lumière, et donc les modes qu'ils supportent ont une extension spatiale ne pouvant être en deçà de l'échelle de la longueur d'onde. Dans ce manuscrit de thèse, nous nous intéressons aux systèmes plasmoniques parce qu'ils supportent des modes confinés à l'échelle nanométrique. En premier lieu, nous étudions une microcavité plasmonique planaire, constituée de deux miroirs plasmoniques qui piègent les ondes de surface au sein du système. Nous sondons spatialement les modes de la cavité en mesurant le temps de vie de fluorescence de molécules individuelles dispersées au sein du système. Puis, nous nous intéressons au confinement en 3 dimensions de modes supportés par des nanoparticules métalliques sphériques. Nous discutons de la définition du volume modal basée sur le calcul du confinement d'énergie autour de la particule. Ensuite, nous étudions l'exaltation de fluorescence d'ions de terres rares au sein d'une particule plasmonique de configuration coeur-coquille. Enfin, nous perturbons la photodynamique d'émission d'une source de photon unique en approchant à proximité l'extrémité d'une pointe plasmonique
Optical microcavities exhibit high resonance quality, so that, they are of key interest for the design of low-threshold lasers or for achieving strong coupling regime. But, such systems support modes whose the volume remain diffraction limited.In this manuscript, we are interested in their plasmonic counterparts because they support confined modes at the sub-wavelength scale. First, we study an in-plane plasmonic cavity which is the transposition of 1D optical cavity to surface wave. We characterize the cavity by measuring the fluorescence lifetime of dye molecules deposited inside.Then, we are interested in 3-dimension mode confinement achieved by spherical metal nanoparticles. We discuss on the definition of the mode volume used in cavity quantum electrodynamic and based on the calculation of energy confinement around the particle. We also simulate the fluorescence enhancement of rare-earth ions embedded inside core-shell plasmonic particles. Finally, we disturb the photodynamic emission of a single-photon source by puttingthe extremity of a plasmonic tip nearby the emitter
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39

Scheffler, Christopher M. "Localized Photoemission in Triangular Gold Antennas." Thesis, Portland State University, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13808008.

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With the development of ultra-fast laser technology, several new imaging techniques have pushed optical resolution past the diffraction limit for traditional light-based optics. Advancements in lithography have enabled the straightforward creation of micron- and nanometer-sized optical devices. Exposing metal-dielectric structures to light can result in surface plasmon excitation and propagation along the transition interface, creating a surface plasmon polariton (SPP) response. Varying the materials or geometry of the structures, the plasmonic response can be tailored for a wide range of applications.

Photoemission electron microscopy (PEEM) has been used to image excitations in micron-sized plasmonic devices. With PEEM, optical responses can be characterized in detail, aiding in the development of new types of plasmonic structures and their applications. We show here that in thin, triangular gold platelets SPPs can be excited and concentrated within specific regions of the material (thickness ~50 nm); resulting in localized photoemission in areas of high electric field intensity. In this regard, the platelets behave as receiver antennas by converting the incident light into localized excitations in specific regions of the gold platelets. The excited areas can be significantly smaller than the wavelength of the incident light (λ ≤ 1 µm). By varying the wavelength of the light, the brightness of the excited spots can be changed and by varying the polarization of the light, the brightness and position can be changed, effectively switching the photoemission on or off for a specific region within the triangular gold structure.

In this work, the spatial distribution of surface plasmons and the imaging results from photoemission electron microscopy are reproduced in simulation using finite element analysis (FEA). In addition, we show that electromagnetic theory and simulation enable a detailed and quantitative analysis of the excited SPP modes, an explanation of the overall optical responses seen in PEEM images, and prediction of new results.

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40

Lupetti, Mattia [Verfasser], and Armin [Akademischer Betreuer] Scrinzi. "Plasmonic generation of attosecond pulses and attosecond imaging of surface plasmons : modeling and simulation of experimental proposals / Mattia Lupetti. Betreuer: Armin Scrinzi." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2015. http://d-nb.info/1073826090/34.

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41

Rogez, Benoit. "Excitation électrique locale de nanostructures plasmoniques par la pointe d'un microscope à effet tunnel." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112383/document.

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Nous utilisons un microscope à effet tunnel (STM) associé à un microscope optique inversé pour l’excitation et la détection des plasmons de surface propagatifs et/ou localisés. L’excitation de ces plasmons est assurée par passage d’un courant tunnel inélastique entre la pointe du STM et la surface d’un film métallique mince (épaisseur de 50 nm) d’or ou d’argent déposé sur une lamelle de verre. Les fuites radiatives des plasmons de surface propagatifs et la lumière émise par les plasmons localisés dans le substrat de verre sont collectées par un microscope optique via un objectif à immersion. Il est alors possible de déterminer à la distribution spatiale et angulaire des émissions issues de ces plasmons de surface excités par STM, ainsi qu’à leur distribution en longueurs d’onde. Dans cette thèse, nous nous sommes intéressés au fonctionnement et à l’émission de lumière sous la pointe d’un microscope à effet tunnel fonctionnant à l’air. Nous montrons que la présence d’eau adsorbée au sein de la jonction tunnel, associée à la boucle d’asservissement du STM induit un mode de fonctionnement oscillant et périodique du STM sans lequel il serait difficile d’exciter les plasmons de surface. Ensuite, nous avons montré qu’il est possible de contrôler la directivité des plasmons de surface propagatifs excités par STM en excitant localement un nanofil d’or déposé sur le film d’or. L’étude détaillée de cette directivité nous a permis de démontrer que, contrairement au cas du nanofil d’or déposé sur verre, un nanofil d’or déposé sur film d’or ne se comporte pas comme un résonateur Fabry Pérot. Nous avons proposé un modèle simple dans lequel le nanofil est assimilé à un réseau linéaire d’antennes. Ce modèle permet de rendre compte des structurations spectrales et spatiales des plasmons de surface sur le film d’or résultant de l’ajout du nanofil d’or. Puis, nous avons étudié le couplage entre des nanofibres organiques fluorescentes (structures excitoniques) et les plasmons de surface propagatifs d’un film métallique d’or ou d’argent sur lequel ces nanofibres sont déposées. Nous avons ainsi montré que (i) la fluorescence de la nanofibre peut exciter des plasmons de surface à la surface du film d’or, (ii) la nanofibre organique agit comme un guide d’onde plasmonique et (iii) qu’il est possible d’injecter des plasmons de surface propagatifs du film excités par STM dans ces modes guidés par la nanofibre. D’autre part, en étudiant la figure d’interférences dans le plan de Fourier, nous avons pu confirmer que l’émission du dipôle sous la pointe STM et les plasmons de surface propagatifs excités par STM sont cohérents, donc issus du même événement tunnel. Enfin, nous discutons les effets du couplage entre des nanocristaux semiconducteurs (quantum dots) individuels et un monofeuillet de graphène. Nous montrons que la présence du graphène réduit d’un facteur ~10 la durée de vie de l’état excité des quantum dots déposés sur graphène par rapport aux quantum dots déposés sur verre. Pour les quantum dots déposés sur graphène, il résulte de cette réduction de la durée de vie de l’état excité, une baisse de l’intensité de fluorescence et une réduction du phénomène de scintillement avec un temps de résidence dans un état brillant globalement plus long que pour les quantum dots déposés sur verre. Les différents résultats obtenus au cours de cette thèse permettent de mieux comprendre l’excitation de plasmons de surface avec un microscope à effet tunnel, le couplage entre nanostructures plasmoniques et le couplage entre une structure plasmonique et une nanostructure excitonique. Ils ouvrent des perspectives intéressantes pour le développement de nanodispositifs hybrides plus complexes liants plasmons et excitons et contrôlés électriquement
We use a scanning tunnelling microscope (STM) to excite propagating and/or localised surface plasmons on a thin metallic film (50 nm thick) made of gold or silver deposited on a glass substrate. The leakage radiation of these STM-excited propagating surface plasmons, and the light emitted by localized plasmons into the glass substrate are collected by an inverted optical microscope equipped with an oil immersion objective. Using this setup, it is possible to image both the spatial and angular distribution of the light emitted into the glass substrate on a cooled-CCD. Sending this light to a spectrometer, it is also possible to obtain the wavelength distribution of these STM-excited plasmons. In this manuscript, we discuss the different operation modes of an STM in air. We show that the thin water layers adsorbed on both the STM tip and sample, along with the STM feedback loop, may give rise to an oscillatory mode of operation. Moreover, this mode turns out to be the most efficient one for plasmon excitation with a STM in air. We then show that, when the STM tip is used to locally excite plasmons on a gold nanowire deposited on a gold film, propagating surface plasmons may be preferentially launched along the nanowire axis. Precise understanding of this directivity allows us to demonstrate that, when deposited on a gold film, gold nanowires do not behave as Fabry-Perot resonators, but may be described quite accurately with a one dimensional antenna array model. With this model, it is thereby possible to explain the complex spatial and spectral characteristics of the STM-excited plasmons on the gold film after the addition of the nanowire. Next, we focus on the coupling between fluorescent organic nanofibres (excitonic nanostructures) and propagating surface plasmons on a metallic film (either gold or silver). We show that when the nanofibres are deposited on the metallic film, (i) their fluorescence can excite propagating surface plasmon, (ii) the nanofibre can act as a plasmonic waveguide, and (iii) it is possible to inject surface plasmons propagating onto the metallic film into the guided plasmonic modes of the nanofibre. Moreover, by studying Fourier space images, we confirmed that the vertical dipole localised under the STM tip and the STM-excited propagating surface plasmons are coherent. We finally study the coupling between individual semiconducting nanocrystals (quantum dots) and a graphene monolayer deposited on a glass substrate. We show that, when deposited on graphene, the fluorescence lifetime of the quantum dots is about 10 times shorter than for the quantum dots deposited on bare glass. This leads to a weaker fluorescence signal and reduced blinking behaviour with longer time spent into a bright state. These results improve our understanding of the STM excitation of surface plasmons. They also provide information on the coupling between plasmonic nanostructures and between plasmonic and excitonic entities. in particular, these results are a promising step toward the conception and the realisation of complex electrically driven hybrid plasmonic/excitonic nanodevices
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42

Lee, Ming-Tao. "Plasmonic Enhanced Fluorescence using Gold Nanorods." Thesis, Linköping University, Department of Physics, Chemistry and Biology, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-57680.

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The aims of this study are to first immobilize positively charged gold nanorods to negatively charged cell culture surfaces. Second, to use polyelectrolytes for controlling the distance between gold nanorods and fluorophores. This is used to optimally determine the distance, of which maximum fluorescence enhancement is achieved, between gold nanorods and fluorophores. In order to approach these aims, we use UV/VIS absorption spectroscopy, fluorescence spectroscopy, atomic force microscopy, and ellipsometry. The results show that we could control the immobilization of gold nanorods on plastic microwell plates and create reproducible polyelectrolyte layers, in order to control the distance between the gold nanorods and fluorophores. In addition, the localized surface plasmon resonance wavelength red shifted as the PELs increased. In conclusion, we found that the maximum fluorescence enhancement of the fluorophores (Cy7) is about 2.3 times at a fluorophores-nanoparticles separation of approximately 9-12 nm. This work contributes some research information towards the design of optical biochip platforms based on plasmon-enhanced fluorescence.

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43

Poncheri, Adam James. "Plasmonic field effects of silver nanoparticle monolayers on poly(phenylene ethynylene) fluorescent polymers of different chain length." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41099.

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The literature on nanomaterials has been flooded with new shapes, sizes, and compositions of nanostructures. The process of developing and characterizing these particles has been broadly accomplished and many interesting and promising properties have been revealed for application in current and developing technologies. In particular, the phenomenon of surface plasmon resonance seen in metallic gold and silver nanoparticles has drawn substantial interest. It has been established that the electromagnetic fields surrounding plasmonic particle surfaces can influence the properties of nearby systems, causing them to experience effects such as enhanced absorption and emission of light or drastically increased conductivity. For this reason, plasmonic nanoparticles are being applied to an endless number of applications for new materials. This thesis investigated the effects of silver nanocube (AgNC) arrays on the photophysical properties of poly(paraphenyleneethynylene) (PPE) fluorescent polymers, a particularly relevant material to the applications of organic-electronics. AgNCs were selected because of their particularly strong plasmonic field, which is enhanced at the sharp features of the cubes. The PPE polymer is an exceptionally fluorescent conjugated polymer that often serves as a building block for polymer-based sensing applications. By monitoring the absorption and emission of the PPE polymer, a better understanding of plasmonic effects on this polymer system was obtained. Compression of the monolayer of AgNCs on the surface of a Langmuir-Blodgett trough can be used for control of interparticle distance and, thus, the plasmon field intensity felt by an adsorbed layer of PPE polymer. In the Chapter 4, PPE (n = 15) emission was monitored as a function of the AgNC plasmonic field. A two-photon process was found to explain the unusual increase then decrease of the fluorescence intensity. This observation was attributed to exciton-exciton annihilation processes within the polymer. The annihilation process is initiated by large enhancements of the polymer absorption rate when plasmonic fields are at their highest (when the AgNCs are compressed to short interparticle distances). In chapter 5, the optical properties of PPE polymers as a function of their chain length and the AgNC density were examined. A simple study was conducted to consider the conformational/geometrical effects on PPE that were caused by the deposition of PPE onto the AgNC topography. In this study, the structure of the absorption and emission profiles were evaluated and used as evidence of polymer interchain interactions, planarization, and even the potential generation of oligomeric species through breaking of conjugation. Fundamental interactions between materials must be evaluated and optimized prior to their use in devices. This thesis serves to shed a little bit of light on the interaction of a well-defined plasmonic particle with a conjugated polymer. The Langmuir-Blodgett technique serves as a critical tool in applying these colloidally produced nanoparticles to 2D arrays in practical applications. The observation of exciton-exciton annihilation at low-energy excitation is an entirely new phenomenon that was initiated by the plasmonic properties of metal nanoparticles. It is the hope of the author that the results contained herein can aide in the use of plasmonic nanoparticles in future devices.
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44

Zhang, Taiping. "Plasmonic-Photonic Hybrid Nanodevice." Phd thesis, Ecole Centrale de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00904658.

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Metallic nano-particles or nano-antennas (NAs) provide a strong spatial confinement down to the sub wavelength regime. However, a key challenge is to address and collect light from those nano-scale systems. The tiny active area of the NA is both an advantage for its miniaturization, and a real limit for the level of the collected signal. Therefore, one needs to reconsider how to drive efficiently such NA. Here, we propose to tackle this important issue by designing and realizing a novel nano-optical device based on the use of a photonic crystal cavity (PC cavity) to generate an efficient coupling between the external source and a NA. In this thesis, we design and realize a novel nano-optical device based on the coupling engineering of a photonic crystal (PC) cavity and a nanoantenna (NA). The research work includes nanodevice design, fabrication and characterization. The PC structures are formed in an InP-based membrane with four InAsP quantum wells are in the centre of the membrane to act as an optical gain material of laser mode. The PC structures include defect mode PC structures and Bloch mode PC structures. The bowtie NAs are placed on the backbone of the PC structures. The fabrication of the PC is done by electron beam lithography. Reactive ion beam etching (RIBE) is used to transmit the patterns of PC structures into the InP layer. The NAs are then deterministically positioned on the PC structures by a second e-beam exposure followed by a lift-off process. Overlay measurements showed that the deviation in the alignment error could be as small as 20nm.Optical properties of the hybrid structure are investigated in both far-field and near-field. The far-field measurement shows that the NA increases the lasing threshold of the PC cavity. The wavelength of the laser is also impacted. Near-field scanning optical microscopy (SNOM) has employed to investigate the near-field optical field distribution. The measurement results show that the NA modifies the mode of the structure and localizes the optical field under it. The modification depends on the position and orientation of the NA.
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Danilov, Artem. "Design, characterisation and biosensing applications of nanoperiodic plasmonic metamaterials." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0110/document.

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Cette thèse considère de nouvelles architectures prometteuses des métamatériaux plasmoniques pour biosensing, comprenant: (I) des réseaux périodiques 2D de nanoparticules d'Au, qui peuvent supporter des résonances des réseaux de surface couplées de manière diffractive; (II) Reseaux 3D à base de cristaux plasmoniques du type d'assemblage de bois. Une étude systématique des conditions d'excitation plasmonique, des propriétés et de la sensibilité à l'environnement local dans ces géométries métamatérielles est présentée. On montre que de tels réseaux peuvent combiner une très haute sensibilité spectrale (400 nm / RIU et 2600 nm / RIU, ensemble respectivement) et une sensibilité de phase exceptionnellement élevée (> 105 deg./RIU) et peuvent être utilisés pour améliorer l'état actuel de la technologie de biosensing the-art. Enfin, on propose une méthode de sondage du champ électrique excité par des nanostructures plasmoniques (nanoparticules uniques, dimères). On suppose que cette méthode aidera à concevoir des structures pour SERS (La spectroscopie du type Raman à surface renforcée), qui peut être utilisée comme une chaîne d'information supplémentaire à un biocapteur de transduction optique
This thesis consideres novel promissing architechtures of plasmonic metamaterial for biosensing, including: (I) 2D periodic arrays of Au nanoparticles, which can support diffractively coupled surface lattice resonances; (II) 3D periodic arrays based on woodpile-assembly plasmonic crystals, which can support novel delocalized plasmonic modes over 3D structure. A systematic study of conditions of plasmon excitation, properties and sensitivity to local environment is presented. It is shown that such arrays can combine very high spectral sensitivity (400nm/RIU and 2600 nm/RIU, respectively) and exceptionally high phase sensitivity (> 105 deg./RIU) and can be used for the improvement of current state-of-the-art biosensing technology. Finally, a method for probing electric field excited by plasmonic nanostructures (single nanoparticles, dimers) is proposed. It is implied that this method will help to design structures for SERS, which will later be used as an additional informational channel for biosensing
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Wang, Jiyong. "Plasmonic Nanoantennas." Thesis, Troyes, 2017. http://www.theses.fr/2017TROY0021.

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Les réponses optiques linéaires et non linéaires de nanoparticules (NPs) plasmoniques fabriquées lithographiquement sont étudiées. La diffusion élastique donne une empreinte digitale des plasmons de surface des NPs, ces derniers exaltant les signaux optiques non linéaires. La dépendance en polarisation de la génération de seconde harmonique (SHG) montre un effet de basculement, qui est analysé à partir des décalages spectraux entre l’excitation et les resonances et des effets d'interférence de SHG. En régime de faible excitation, en plus d'un processus de recombinaison de paires électron-trou (e-h), les plasmons de particules (PPs) peuvent être excités par diffusion Auger avec une décroissance radiative donnant lieu à une photoluminescence métallique (MPL). Un modèle de l'efficacité quantique totale des émissions impliquant les deux contributions a été établi. En régime de forte excitation, une avalanche de photoluminescence multiphotonique (AMPL) est observée sur des hétérodimères couplés. Elle est interprétée par une recombinaison des porteurs chauds excités par ionisation multiphotonique (MI). Ce processus est assisté par le champ local des NPs. L'avalanche d’émission peut être évaluée en fonction de l'environnement du champ local et du facteur thermique des porteurs chauds. Le changement spectral du spectre d’émission indique une émission spontanée de paires e-h chaudes s'expliquant par une diminution du taux de diffusion des trous de la bande d lorsque la température augmente
Linear and nonlinear optical responses of lithographically fabricated plasmonic nanoparticles (NPs) are investigated. Elastic scattering offers the fingerprints for localized surface plasmon resonances of NPs, which enhance nonlinear optical signals. Excitation polarization dependent far-field radiation of second-harmonic generation (SHG) shows a flipping effect, which is analysed from the aspects of resonant excitation shifting and SH phase interference as size changes. The radiations of metallic photoluminescence (MPL) in the weak and strong radiation field are studied sequentially. In the weak excitation, besides a process via electron-hole (e-h) pair recombination, particle plasmons (PPs) can be excited via Auger scattering of photo-excited d-band holes and the radiative decay of which gives rise to PPs modulated MPL. A model of total emission quantum efficiency involving both contributions has been used to explain MPL radiation difference between the bulk and the NPs. In the strong excitation, avalanche multiphoton PL (AMPL) is observed from the coupled heterodimers, which is interpreted as the recombination of avalanche ionized hot carriers seeded by multiphoton ionization (MI). MI is greatly assisted by local field of coupled NPs at the excitation stage. The giant photon emission can be evaluated as a function of local field environment and thermal factor of hot carriers. The spectral change from PPs modulated profile to the one indicates spontaneous emission of hot e-h pairs is explained by the diminishment of d-band hole scattering rate as temperature increases
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47

Kvapil, Michal. "Plasmonic Antennas." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-234590.

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Tato disertační práce pojednává o plazmonických anténách. Rezonanční vlastnosti plazmonických antén jsou studovány teoreticky i experimentálně. Teoretické výpočty jsou prováděny v programu Lumerical FDTD Solutions užitím numerické metody konečných diferencí v časové doméně. Pro experimentální studium byly antény vyrobeny pomocí elektronové litografie. Rezonanční vlastnosti vyrobených antén jsou studovány fourierovskou infračervenou spektroskopií. Práce se zaměřuje na studium rezonančních vlastností antén vyrobených na vrstvě nanokrystalického diamantu. Dále zkoumá možnost využití antén jako plazmonického senzoru funkcionalizovaného k detekci streptavidinu. Nakonec je představena anténa tvaru písmene V, u které dochází v důsledku porušení symetrie antény ke směrovému rozptylu dopadajícího světla. Tato směrovost se ovšem projevuje jen na vlnových délkách blízkých kvadrupólovému módu antény.
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48

Tahir, Asad Ahmad. "Plasmonic Metasurfaces." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34961.

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Nanophotonics is a booming field of research with the promise of chip-scale devices which harness the tremendous potency of light. In this regard, surface plasmons have shown great potential for confining and manipulating light at extreme sub-wavelength scales. Advances in fabrication technology have enabled the scientific community to realize metasurfaces with unconventional properties that push the limits of possible applications of light. This thesis is comprised of computational and experimental studies on plasmonic metasurfaces. The computational study presents efficient design principles for plasmonic half-wave plates using L-shaped nanoantennas. These principles can be used to design waveplates at an operating wavelength of choice and for specific application requirements. The impact of this study goes beyond the efficient design of waveplates: it provides useful insights into the Physics of L-shaped nanoantenna arrays which have been proposed as building blocks for plasmonic metasurfaces. The experimental work investigates the interaction of a plasmonic metasurface, composed of dipole antenna arrays, with an epsilon-near-zero (ENZ) material. This work thus forms a bridge between plasmonics and ENZ materials science, which is a rapidly advancing field in its own right. The first experimental study investigates the exciting unconventional response of plasmonic dipole antennas when placed on a thin indium tin oxide (ITO) film near its ENZ wavelength of 1417 nm. The antenna-on-ITO system has split resonances whose spectral positions are largely independent of the antenna dimensions. The resonance splitting occurs due to coupling between the antenna resonance and the ENZ mode of the ITO film. This coupling results in field intensity enhancements on the order of a 100 in the ITO film. The second experimental study demonstrates, using the z-scan method, that this large field enhancement in the antenna-on-ITO structure further enhances the already strong nonlinearity of ITO around its ENZ wavelength. In particular, the antenna-on-ITO structure exhibits an extremely large nonlinear absorption coefficient, which is two orders of magnitude larger than that of a bare ITO film, and three to five orders of magnitude larger than that of many other nonlinear materials. This thesis thus constitutes a beautiful blend of three thriving areas of research: plasmonics, ENZ materials science and nonlinear optics. The findings reported here have the potential to contribute to all of these fields, and thus have relevance to a broad spectrum of optical scientists.
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Samaimongkol, Panupon. "Surface plasmon resonance study of the purple gold (AuAl2) intermetallic, pH-responsive fluorescence gold nanoparticles, and gold nanosphere assembly." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/96549.

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In this dissertation, I have verified that the striking purple color of the intermetallic compound AuAl2, also known as purple gold, originates from surface plasmons (SPs). This contrasts to a previous assumption that this color is due to an interband absorption transition. The existence of SPs was demonstrated by launching them in thin AuAl2 films in the Kretschmann configuration, which enables us to measure the SP dispersion relation. I observed that the SP energy in thin films of purple gold is around 2.1 eV, comparable to previous work on the dielectric function of this material. Furthermore, SP sensing using AuAl2 also shows the ability to measure the change in the refractive index of standard sucrose solution. AuAl2 in nanoparticle form is also discussed in terms of plasmonic applications, where Mie scattering theory predicts that the particle bears nearly uniform absorption over the entire visible spectrum with an order magnitude higher than a lightabsorbing carbonaceous particle. The second topic of this dissertation focuses on plasmon enhanced fluorescence in gold nanoparticles (Au NPs). Here, I investigated the distance-dependent fluorescence emission of rhodamine green 110 fluorophores from Au NPs with tunable spacers. These spacers consist of polyelectrolyte multilayers (PEMs) consisting of poly(allylamine hydrochloride) and poly(styrene sulfonate) assembled at pH 8.4. The distance between Au NPs and fluorophores was varied by changing the ambient pH from 3 to 10 and back, which causes the swelling and deswelling of PEM spacer. Maximum fluorescence intensity with 4.0-fold enhancement was observed with 7-layer coated Au NPs at ambient pH 10 referenced to pH 3. The last topic of this dissertation examines a novel approach to assemble nanoparticles, in particular, dimers of gold nanospheres (NSs). 16 nm and 60 nm diameter NSs were connected using photocleavable molecules as linkers. I showed that the orientation of the dimers can be controlled with the polarization of UV illumination that cleaves the linkers, making dipolar patches. This type of assembly provides a simple method with potential applications in multiple contexts, such as biomedicine and nanorobotics.
PHD
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Cetnar, John. "Full Wave Electromagnetic Simulations of Terahertz Wire Grid Polarizers and Infrared Plasmonic Wire Gratings." Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1398356024.

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