Дисертації: "Optical Plasmons"

1

Jory, Michael John. "Optical sensing with surface plasmons." Thesis, University of Exeter, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240308.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

2

Lin, Ling. "Optical Manipulation Using Planar/Patterned Metallo-dielectric Multilayer Structures." Thesis, University of Canterbury. Electrical and Computer Engineering, 2008. http://hdl.handle.net/10092/1249.

Повний текст джерела

Анотація:

Tailoring surface plasmon (SP) resonances using metallic nanostructures for optical manipulation has been widely investigated in recent years; and there are many puzzles yet to be solved in this relatively new area. This thesis covers the study of the interaction of light with SP-supporting planar/patterned metallo-dielectric multilayer structures. Two separate, but closely related subjects were investigated using such structures, which are: SP-assisted optical transmission and optical metamaterials. The physical mechanisms of the SP-assisted transmission phenomenon were studied using planar/grating and planar/hole-array multilayer structures. Extraordinary light transmission has been demonstrated through experimental work and simulations for both arrangements; and the effects of different structural parameters on the transmission efficiencies of the structures were analyzed systematically. The interplays of the surface plasmon polaritons (SPPs) and localized surface plasmons (LSPs) in the extraordinary optical transmission (EOT) phenomenon were identified. The potential of the planar/hole-array multilayer structures as optical magnetic metamaterials was evaluated using two independent electromagnetic simulation techniques. The ability of such structures to produce strong magnetic resonances from infrared down to visible side of spectrum was revealed. The methods of tuning the magnetic response of the structures were suggested. A novel design of optical metamaterial based on high-order multipolar resonances in a single-layer plasmonic structure was also proposed. Numerical results from two different computation methods indicate that a simultaneously negative permittivity and permeability can be achieved in such a structure.

Стилі APA, Harvard, Vancouver, ISO та ін.

3

Scales, Christine. "Magneto-plasmons in optical slab waveguides." Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26765.

Повний текст джерела

Анотація:

The effect of an externally applied magnetic field on the propagation characteristics of a plasmon-polariton wave supported by an infinitely wide thin metal waveguide was investigated. In order to do so, the dispersion relation was derived, from Maxwell's equations, enabling accurate modelling of the situation of interest. The general dispersion relation, including the constraint equation, for magneto-plasmons was derived in general, and then, specifically for a magnetic field applied along three orthogonal cartesian axes. The losses in the metal were included in the dispersion equation so that a better understanding of the influence of an externally applied magnetic field may be provided. The dispersion relation is used as the basis of a software model of magneto-plasmons in thin metal films. This model is validated against specific cases in the literature with and without an externally applied magnetic field. The specific formulations in the literature were deemed to be incorrect, and have been corrected and the results have been interpreted. The model is then used to simulate thin gold films bounded by silicon dioxide at an infrared wavelength. The modelling results include the effect of the externally applied magnetic field on the propagation constant and the corresponding field components for all three Cartesian orientations of externally applied magnetic field. The results from these simulations are presented and interpreted. (Abstract shortened by UMI.)

Стилі APA, Harvard, Vancouver, ISO та ін.

4

George, Sebastian. "Optical and Magneto-Optical Measurements of Plasmonic Magnetic Nanostructures." Thesis, Uppsala universitet, Materialfysik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-229511.

Повний текст джерела

Анотація:

At the interface between a metal and dielectric, it is possible for an electromagnetic wave to couple with the conduction electrons of the metal to create a coupled oscillation known as a surface plasmon. These surface plasmons can exhibit properties which are not shared with their purely electronic or electromagnetic components. Such unique properties include the ability to transmit plasmonic waves through sub-wavelength spaces, opening up the possibility of combining the high data density seen in photonics-based information technologies with the nanometer-scale electronic components of modern integrated circuitry. Other plasmon properties such as the highly resonant nature of plasmon excitation may potentially lend themselves to novel cancer treatments and medical probing techniques. In order to develop such technologies, a deeper understanding of surface plasmons and their relationship with a material’s properties and structure is necessary. In the present work, angle- and energy-resolved optical measurements for a square lattice of circular Fe20Pd80 islands are presented in the form of reflectivity and transmission maps, along with higher resolution reflectivity, transmission, and TMOKE measurements for a few specific wavelengths. A theoretical model describing the connection between plasmonic and magneto-optical behavior is described and compared with the experimental data, showing a very high correlation.

Стилі APA, Harvard, Vancouver, ISO та ін.

5

Auguié, Baptiste. "Optical properties of gold nanostructures." Thesis, University of Exeter, 2009. http://hdl.handle.net/10036/73955.

Повний текст джерела

Анотація:

The optical properties of gold in the visible are dominated by the response of the free conduction electrons to light. In gold nanostructures, the surface charge density adopts a configuration that is constrained by the shape of the nanoparticles. As a result, the scattering of light by gold nanoparticles exhibits a resonant response characterised by a strong scattering and absorption in a narrow range of frequencies. The spectral range of this \emph{localised surface plasmon resonance} (LSPR) can be tuned by varying the size and shape of the gold nanoparticle --- the nanoparticles act as nanoscale antennas for the visible light. Confirmation of this scaling rule is obtained by conducting experiments with nanoparticles of varying size and aspect ratio. Such particles are fabricated by electron-beam lithography, and characterised by dark-field spectroscopy. Not only does the LSPR shift in frequency with a change of particle size, but its spectral lineshape is also modified. The intensity and width of the LSPR are dictated by a variety of factors that are related to the intrinsic material properties (the complex dielectric function of gold), and to the particle geometry and environment. The optical response of small gold nanorods is well described by a simple oscillating dipole model --- the incident electromagnetic field induces a current in the particle that re-radiates light (scattering). A series of refinements can be made to model more accurately the optical response of realistic particles. If the dipole moment characterising the particle is allowed to vary in phase across the particle, retardation effects provide a correction for the effective dipole moment of the particle. As the particle size approaches the wave length in the surrounding medium, the dipolar approximation breaks down and higher order multipoles need to be considered. The Mie theory provides a very accurate description of the response of spheres of arbitrary size. Further, the T-matrix and other numerical techniques can be employed to accurately reproduce the scattering properties of particles of arbitrary shapes. When the scattering sample consists of a collection of gold nanoparticles, the collective optical response is affected by two key factors. First, the measured LSPR is a convolution of the distribution of particle sizes with the individual response of a single particle. This leads to an inhomogeneous broadening of the LSPR lineshape. Second, the light that is scattered by one such particle near resonance can strongly affect its neighbours which scatter light in proportion to the net field they experience, that is the sum of the incident field plus the perturbation arising from the neighbouring particles. The onset of such multiple scattering events is observed even for particle separations that are several times larger than the particle size. Several regimes of interaction can be distinguished according to the ratio separation / wavelength. First, when the particles are in close proximity (separation $\ll$ wavelength), near-field interactions dominate and result in a spectral shift of the LSPR accompanied with a spectral broadening. Second, when the separation is commensurate with the wavelength, a coherent interaction can develop that couples a large number of particles. In ordered arrays, such coupling gives rise to a geometrical resonance that can strongly affect the LSPR of the particles. In particular a sharp spectral feature is observed that depends on both the single particle response and the geometrical arrangement of the particles in the array. The coherence of such multiple scattering in diffractive arrays of gold nanoparticles can be broken by introducing disorder in the distribution of particle sizes, or in the particle positions. The optical properties of an irregular array reflect the departure from a periodic system and the spectral lineshape evolves as the level of disorder is increased. In the limit of uncorrelated positions, the diffractive coupling is suppressed and the response of the collection of the particles rejoins the response of isolated particles.

Стилі APA, Harvard, Vancouver, ISO та ін.

6

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

Повний текст джерела

Анотація:

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.

Стилі APA, Harvard, Vancouver, ISO та ін.

7

Iyer, Srinivasan. "Effects of surface plasmons in subwavelength metallic structures." Doctoral thesis, KTH, Optik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103613.

Повний текст джерела

Анотація:

The study of optical phenomena related to the strong electromagnetic response of noble metals (silver (Ag) and gold (Au) being most popular) over the last couple of decades has led to the emergence of a fast growing research area called plasmonics named after 'surface plasmons' which are electron density waves that propagate along the interface of a metal and a dielectric medium. Surface plasmons are formed by the coupling of light to the electrons on the metal surface subject to the fulfillment of certain physical conditions and they are bound to the metal surface. Depending on whether the metallic medium is a continuous film or a structure having dimensions less than or comparable to the wavelength of the exciting light, propagating or localized surface plasmons can be excited. The structure can be either a hole or an arbitrary pattern in a metal film, or a metallic particle. An array of subwavelength structures can behave as an effective homogeneous medium to incident light and this is the basis of a new class of media known as metamaterials. Metallic metamaterials enable one to engineer the electromagnetic response to incident light and provide unconventional optical properties like negative refractive index as one prominent example. Metamaterials exhibiting negative index (also called negative index materials (NIMs)) open the door for super resolution imaging and development of invisibility cloaks. However, the only problem affecting the utilization of plasmonic media to their fullest potential is the intrinsic loss of the metal, and it becomes a major issue especially at visible-near infrared (NIR) frequencies. The frequency of the surface plasmon is the same as that of the exciting light but its wavelength could be as short as that of X-rays. This property allows light of a given optical frequency to be conned into very small volumes via subwave lengthmetallic structures, that can be used to develop ecient sensors, solar cells, antennas and ultrasensitive molecular detectors to name a few applications. Also, interaction of surface plasmons excited in two or more metallic subwavelength structures in close proximity inuences the far-eld optical properties of the overall coupled system. Some eects of plasmonic interaction in certain coupled particles include polarization conversion, optical activity and transmission spectra mimicking electromagnetically-induced transparency (EIT) as observed in gas based atomicsy stems. In this thesis, we mainly focus on the optical properties of square arrays of certain plasmonic structures popularly researched in the last decade. The structures considered are as follows: (1) subwavelength holes of a composite hole-shape providing superior near-eld enhancement such as two intersecting circles (called' double hole') in an optically thick Au/Ag lm, (2) double layer shnets, (3) subwavelength U-shaped particles and (4) rectangular bars. The entire work is based on electromagnetic simulations using time and frequency domain methods. Au/Ag lms with periodic subwavelength holes provide extraordinarily high transmission of light at certain wavelengths much larger than the dimension of the perforations or holes. The spectral positions of the maxima depend on the shape of the hole and the intra-hole medium, thereby making such lms function as a refractive index sensor in the transmission mode. The sensing performance of the double-hole geometry is analyzed in detail and compared to rectangular holes. Fishnet metamaterials are highly preferred when it comes to constructing a NIM at optical frequencies. A shnet design that theoretically oers a negative refractive index with least losses at telecommunication wavelengths (1.4 1.5 microns) is presented. U-shaped subwavelength metallic particles, in particular single-slit split-ring resonators (SSRRs), provide a large negative response to the magnetic eld of light at a specic resonance frequency. The spectral positions of the structural resonances of the U-shaped particle can be found from its array far field transmission spectrum at normal incidence. An effort is made to clarify our understanding of these resonances with the help of localized surface plasmon modes excited in the overall particle. From an application point of view, it is found that a planar square array of SSRRs eectively functions as an optical half-wave waveplate at the main resonance frequency by creating a polarization in transmission that is orthogonal to that of incident light. A similar waveplate eect can be obtained purely by exploiting the near-eld interaction of dierently oriented neighbouring SSRRs. The physical reasons behind polarization conversion in dierent SSRR-array systems are discussed. A rectangular metallic bar having its dipolar resonance in the visible-NIR is called a nanoantenna, owing to its physical length in the order of nanometers. The excitation of localized surface plasmons, metal dispersion and the geometry of the rectangular nanoantenna make an analytical estimation of the physical length of the antenna from the desired dipolar resonance dicult. A practical map of simulated resonance values corresponding to a variation in geometrical parameters of Au bar is presented. A square array of a coupled plasmonic system comprising of three nanoantennas provides a net transmission response that mimicks the EIT effect. The high transmission spectral window possesses a peculiar dispersion profile that enables light with frequencies in that region to be slowed down. Two popular designs of such plasmonic EIT systems are numerically characterized and compared.

QC 20121017

Стилі APA, Harvard, Vancouver, ISO та ін.

8

Kurth, Martin L. "Plasmonic nanofocusing and guiding structures for nano-optical sensor technology." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/118670/1/Martin_Kurth_Thesis.pdf.

Повний текст джерела

Анотація:

This thesis investigated factors affecting the sensitivity of nano-optical sensors that could be used for the detection of trace amounts of explosives and environmental pollutants in air. By delivering air to regions of enhanced electric field produced by metallic nanostructures, as well as using structures that localise and guide light at nanoscale levels, detection limits can be reduced.

Стилі APA, Harvard, Vancouver, ISO та ін.

9

Jia, Kun. "Optical detection of (bio)molecules." Thesis, Troyes, 2013. http://www.theses.fr/2013TROY0032/document.

Повний текст джерела

Анотація:

Les biocapteurs optiques ont connu une évolution sans précédent au cours des dernières années, principalement en raison de la forte interaction entre la biotechnologie, l’optique et la chimie des matériaux. Dans cette thèse, deux différentes plates-formes de biocapteurs optiques ont été conçues pour la détection sensible et spécifique des biomolécules. Plus précisément, le premier système de détection optique est construit sur la base de la bioluminescence de cellules bactériennes d'Escherichia coli génétiquement modifiées. L’émission de lumière induite par cette interaction peut donc être utilisée pour la détection des substances toxiques. Le second système utilise des nanoparticules de métaux précieux (or et argent) aux propriétés plasmoniques accordables qui permettent de sonder les interactions des biomolécules spécifiques à l'interface nano-bio par la résonance plasmonique de surface (LSPR). Ces nanoparticules ont été obtenues par traitement thermique à haute température d’un film métallique déposé sur du verre à l’aide d’une grille de TEM ou déposé sur une couche de bactéries fixée sur le verre. Après une optimisation appropriée des nanostructures métalliques en termes de morphologie et de fonctionnalisation, une sensibilité élevée et une grande spécificité peuvent être simultanément obtenues avec ces immunocapteurs plasmonique. Ces deux plateformes ont été utilisées pour détecter des pesticides comme le carbofuran et l’atrazine
Optical biosensors have witnessed unprecedented developments over recent years, mainly due to the lively interplay between biotechnology, optical physics and materials chemistry. In this thesis, two different optical biosensing platforms have been designed for sensitive and specific detection of (bio)molecules. Specifically, the first optical detection system is constructed on the basis of bioluminescence derived from engineered Escherichia coli bacterial cells. Upon stressed by the toxic compounds, the bacterial cells produce light via a range of complex biochemical reactions in vivo and the resulted bioluminescent evolution thus can be used for toxicant detection. The bacterial bioluminescent assays are able to provide competitive sensitivity, while they are limited in the specificity. Therefore, the second optical detection platform is built on the localized surface plasmon resonance (LSPR) immunosensors. In this optical biosensor, the noble metal (gold and silver) nanoparticles with tunable plasmonic properties are used as transducer for probing the specific biomolecules interactions occurred in the nano-bio interface. These nanoparticles were obtained after a high temperature thermal treatment of an initially thin-metallic film deposited on a glass substrate through a TEM grid or on a bacteria layer fixed on the glass. After appropriate optimization on metal nanostructures morphology and surface biomodification, the applicable sensitivity and specificity can be both guaranteed in this LSPR immunosensor

Стилі APA, Harvard, Vancouver, ISO та ін.

10

Chinowsky, Timothy Mark. "Optical multisensors based on surface plasmon resonance /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/5857.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

11

Constant, Thomas J. "Optical excitation of surface plasmon polaritons on novel bigratings." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/9001.

Повний текст джерела

Анотація:

This thesis details original experimental investigations in to the interaction of light with the mobile electrons at the surface of metallic diffraction gratings. The gratings used in this work to support the resultant trapped surface waves (surface plasmon polaritons), may be divided into two classes: ‘crossed’ bigratings and ‘zigzag’ gratings. Crossed bigratings are composed of two diffraction gratings formed of periodic grooves in a metal surface, which are crossed at an angle relative to one another. While crossed bigratings have been studied previously, this work focuses on symmetries which have received comparatively little attention in the literature. The gratings explored in this work possesses two different underlying Bravais lattices: rectangular and oblique. Control over the surface plasmon polariton (SPP) dispersion on a rectangular bigrating is demonstrated by the deepening of one of the two constituent gratings. The resulting change in the diffraction efficiency of the surface waves leads to large SPP band-gaps in one direction across the grating, leaving the SPP propagation in the orthogonal direction largely unperturbed. This provides a mechanism to design surfaces that support highly anisotropic propagation of SPPs. SPPs on the oblique grating are found to mediate polarisation conversion of the incident light field. Additionally, the SPP band-gaps that form on such a surface are shown to not necessarily occur at the Brillouin Zone boundaries of this lattice, as the BZ boundary for an oblique lattice is not a continuous contour of high-symmetry points. The second class of diffraction grating investigated in this thesis is the new zigzag grating geometry. This grating is formed of sub-wavelength (non-diffracting) grooves that are ‘zigzagged’ along their length to provide a diffractive periodicity for visible frequency radiation. The excitation and propagation of SPPs on such gratings is investigated and found to be highly polarisation selective. The first type of zigzag grating investigated possesses a single mirror plane. SPP excitation to found to be dependant on which diffracted order of SPP is under polarised illumination. The formation of SPP band-gaps is also investigated, finding that the band-gap at the first Brillouin Zone boundary is forbidden by the grating’s symmetry. The final grating considered is a zigzag grating which possesses no mirror symmetry. Using this grating, it is demonstrated that any polarisation of incident light may resonantly drive the same SPP modes. SPP propagation on this grating is found to be forbidden in all directions for a range of frequencies, forming a full SPP band-gap.

Стилі APA, Harvard, Vancouver, ISO та ін.

12

Kolkowski, Radoslaw. "Studies of nonlinear optical properties of plasmonic nanostructures." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLN001/document.

Повний текст джерела

Анотація:

Le but de cette thèse et de la recherche associée est une démonstration des avantages d’une combinaison de propriétés inhabituelles de nanostructures plasmoniques avec des aspects parmi les plus intéressants de l’optique non-linéaire. Pour cet effet, la modélisation analytique et numérique a été combiné avec le travail expérimental, qui comprenait la production de nanostructures et les mesures effectuées au moyen de la microscopie confocale non-linéaire résolue en polarisations et de la technique Z-scan modifiée (nommée “f-scan”).Il a été montré que l’anisotropie efficace de génération de seconde-harmonique dans les cristaux plasmoniques (formés par des réseaux rectangulaires de cavités tétraédriques sur une surface d’argent) peut être contrôlée par un choix approprié des paramètres de maille. Il a aussi été montré que cette anisotropie provient principalement d’une structure de bande photonique elle-même anisotrope, présentant une bande interdite plasmonique avec des états plasmoniques en bord de bande, permettant de renforcer le champ électrique local. Les arrangements chiraux bidimensionnels de nanoparticules triangulaires d’or, forment des “meta-molécules” plasmoniques énantiomériques, ont été analysés par microscopie non-linéaire à la lumière polarisée circulairement et par modélisation numérique, révélant un fort effet chiroptique par génération de seconde harmonique en rétro-réflexion. La petite taille des énantiomères uniques permet de créer “des filigranes” (“watermarks”) codés par la chiralité des meta-molécules, qui peuvent être lu par imagerie de la génération de seconde harmonique excitée par un rayon polarisé circulairement. Les caractéristiques quantitatives de la non-linéarité optique du troisième ordre et de l’efficacité d’absorption saturable des solutions aqueuses de fragments de graphène et de graphène dopé par des nanoparticules d’or a été effectuée par une nouvelle technique “f-scan”, qui a été créée et développée par incorporation d’une lentille à distance focale accordable dans une technique de Z-scan traditionnelle. Ces études ont montrées que le graphène présente une absorption saturable ultra-rapide très efficace, qui est parfois convertie en absorption saturable inverse. Il apparaît alors qu’une décoration du graphène par des nanoparticules d’or peut causer une légère amélioration du paramètre d’efficacité d’absorption saturable dans la plage spectrale de leurs résonances plasmoniques. En résumé, cette thèse présente une variété de propriétés optiques non-linéaires apparaissant dans les nanostructures plasmoniques. Différentes possibilités de contrôle de ces propriétés au moyen d’une démarche de nano-ingénierie, soutenue par des modélisations à la fois analytique et numérique ont été démontrées et analysées. Ces travaux ouvrent la voie à la fabrication et à l‘optimisation sur mesure de nouveaux nano-matériaux et nano-dispositifs photoniques reposant sur des effets de nano-plasmonique non-linéaire
The aim of this thesis and the underlying research work is to demonstrate the benefits emerging from combination of the peculiar properties of plasmonic nanostructures with the most interesting aspects of nonlinear optics. For this purpose, analytical and numerical modeling was combined with experimental work, which included nanofabrication and measurements performed by means of polarization-resolved nonlinear confocal microscopy and by modified Z-scan technique (called "f-scan").It has been shown that the effective anisotropy of the second-harmonic generation in plasmonic crystals (formed by rectangular arrays of tetrahedral recesses in silver surface) can be controlled by proper choice of lattice constants. It also has been shown that this anisotropy arises mainly from the anisotropic photonic band structure, exhibiting plasmonic band gap with plasmonic band edge states, enabling enhancement of the local electric field.Two-dimensional chiral arrangements of triangular gold nanoparticles, forming plasmonic enantiomeric "meta-molecules", have been studied by nonlinear microscopy operating with circularly polarized light and by numerical modeling, revealing strong chiroptical effect in backscattered second-harmonic radiation. Small size of individual enantiomers allows to create "watermarks", encoded by the chirality of meta-molecules, which can be readout by imaging of second-harmonic generation excited by circularly polarized laser beam.Quantitative characterization of the third-order optical nonlinearity and saturable absorption efficiency of aqueous solutions of graphene and gold-nanoparticle decorated graphene has been performed by novel "f-scan" technique, which has been created and developed by incorporation of a focus-tunable lens into traditional Z-scan. These studies have shown that the graphene exhibits very efficient ultrafast saturable absorption, which is occasionally suppressed by reverse saturable absorption. Moreover, it turns out that decoration of graphene by gold nanoparticles may cause a slight improvement of the saturable absorption efficiency parameter within spectral range of their plasmon resonances.In summary, the following thesis presents various nonlinear optical properties of plasmonic nanostructures. Different possibilities of controlling these properties by means of nano-engineering, supported by analytical and numerical modeling, is also analyzed and demonstrated. This work opens up new perspectives for fabrication and rational design of novel photonic nano-materials and nano-devices based on nonlinear nanoplasmonic phenomena

Стилі APA, Harvard, Vancouver, ISO та ін.

13

Devilez, Alexis. "Optical microlenses and nanoantennas." Aix-Marseille 3, 2010. http://www.theses.fr/2010AIX30058.

Повний текст джерела

Анотація:

Cette thèse étudie les interactions de la lumière avec des particules de taille mierométrique et nanométrique. Les particules sont des composants optiques s'inscrivant dans un besoin de miniaturisation des systèmes optiques. Deux grands types de particules sont distingués dans ce manuscrit. D'une part, les particules diélectriques de taille mierométriques permettent de focaliser la lumière de manière analogue aux lentilles conventionnelles. Nous avons démontre que lorsque cette même bille est éclairée par un faisceau préalablement focalisé, une interférence destructive permet de réduire significativement le volume focal dans toutes les directions de l'espace. Il est important de noter que de telles performances n'avaient été réalisées qu'à l'aide de structures complexes de type métalliques ou de cristaux photoniques. Un second type de particules connaissant un regain d'intérêt en optique sont les particules métalliques qui supportent des résonances plasmoniques dans le domaine optique. Ces résonances produisent d'intenses champs électromagnétiques au voisinage de particules nanométriques, plus petites que la longueur d'onde optique. De fortes interactions entre plasmons localisés permettent également un contrôle de la position du point focal à des échelles bien inférieures à la longueur d'onde optique incidente. Du fait des dimensions de l'ordre du nanomètre des volumes de focalisation de ces « nanolentilles », il devient possible d'interagir directement avec un émetteur unique placé dans le voisinage de la particule comme une molécule fluorescente ou une boite quantique. La particule permet d'augmenter et de réorienter le signal émis par l'émetteur dans son voisinage. La particule joue ainsi le rôle de « nanoantenne » permettant de coupler une onde propagative à un état localisé de la matière et réciproquement
This thesis studies the interactions of light with particles of micrometric and nanometric size. The particles are optical components as part of a need for miniaturization of optical systems. Two major types of particles are distinguished in this manuscript. On the one hand, the micrometer-sized dielectric particles can focus light in a manner similar to conventional lenses. We have shown that when this particle is illuminated by a previously focused beam, destructive interferences significantly produce a small focal volume dimension in all directions in space. It is important to note that such performances had been achieved only by using complex structures like metal or photonic crystals. Metallic particles have also raised a great interest since they support plasmonic resonances in the optical domain. These resonances produce intense electromagnetic fields in the vicinity ofnanopartieles, smaller than the optical wavelength. Strong interactions between localized plasmons can also enable the control of the focal position at scales well below the optical wavelength incident. Given the scale of the nanometer focal volumes of these "nanolenses, it becomes possible to interact directly with a single emitter placed in the vicinity of the particle such as a fluorescent molecule or a quantum dot. The particle can increase and redirect the signal from the emitter located in its vicinity. The particle plays thus the role of "nanoantenna" for coupling propagative waves to localized states of matter and vice versa

Стилі APA, Harvard, Vancouver, ISO та ін.

14

Wang, Haining. "Novel optical properties of metal nanostructures based on surface plasmons." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5720.

Повний текст джерела

Анотація:

Surface plasmons have been attracted extensive interests in recent decades due to the novel properties in nanometer sized dimensions. My work focused on the novel optical properties of metal nanostructures based on surface plasmons using theoretical simulation methods. In the first part, we investigated metal nanofilms and nanorods and demonstrated that extremely low scattering efficiency, high absorption efficiency and propagation with long distance could be obtained by different metal nanostructures. With a perforated silver film, we demonstrated that an extremely low scattering cross section with an efficiency of less than 1% can be achieved at tunable wavelengths with tunable widths. The resonance wavelength, width, and intensity are influenced by the shape, size and arrangement pattern of the holes, as well as the distance separating the holes along the polarization direction. The extremely low scattering could be used to obtain high absorption efficiency of a two-layer silver nanofilm. Using the discrete dipole approximation method, we achieved enhanced absorption efficiencies, which are close to 100%, at tunable wavelengths in a two-layer silver thin film. The film is composed of a 100 nm thick perforated layer facing the incident light and a 100 nm thick solid layer. Resonance wavelengths are determined by the distances between perforated holes in the first layer as well as the separation between two layers. The resonance wavelengths shift to red with increasing separation distance between two layers or the periodic distance of the hole arrays. Geometries of conical frustum shaped holes in the first layer are critical for the improved absorption efficiencies. When the hole bottom diameter equals the periodic distance and the upper diameter is about one-third of the bottom diameter, close to unit absorption efficiency can be obtained. We examined the electromagnetic wave propagation along a hollow silver nanorod with subwavelength dimensions. The calculations show that light may propagate along the hollow nanorod with growing intensities. The influences of the shape, dimension, and length of the rod on the resonance wavelength and the enhanced local electric field, |E|2, along the rod were investigated. In the second part, a generalized electrodynamics model is proposed to describe the enhancement and quenching of fluorescence signal of a dye molecule placed near a metal nanoparticle (NP). Both the size of the Au NPs and quantum yield of the dye molecule are crucial in determining the emission intensity of the molecule. Changing the size of the metal NP will alter the ratio of the scattering and absorption efficiencies of the metal NP and consequently result in different enhancement or quenching effect to the dye molecule. A dye molecule with a reduced quantum yield indicates that the non-radiative channel is dominant in the decay of the excited dye molecules and the amplification of the radiative decay rate will be easier. In general, the emission intensity will be quenched when the size of metal NP is small and the quantum yield of dye molecule is about unity. A significant enhancement factor will be obtained when the quantum yield of the molecule is small and the particle size is large. When the quantum yield of the dye molecule is less than 10-5, the model is simplified to the surface enhanced Raman scattering equation.
Ph.D.
Doctorate
Chemistry
Sciences
Chemistry

Стилі APA, Harvard, Vancouver, ISO та ін.

15

Pollard, Jeremy David. "Optical excitation of surface plasmons at metal/organic fluid boundaries." Thesis, University of Exeter, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253622.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

16

Johnston, Kyle S. "Planar substrate surface plasmon resonance probe with multivariant calibration /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/6069.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

17

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.

Повний текст джерела

Анотація:

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.

Стилі APA, Harvard, Vancouver, ISO та ін.

18

Tyson, Robin Edward. "Far-infrared optical studies of low-dimensional electron systems." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338068.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

19

Otomalo, Tadele. "Ultrafast optical response of complex plasmonic nanoparticles." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC102.

Повний текст джерела

Анотація:

Les propriétés remarquables associées à la résonance plasmon localisée (LSPR) dans les nanoparticules (NP) de métaux nobles font de la plasmonique un sujet aux applications multiples. Lorsque les NP sont éclairées par des impulsions laser ultracourtes, une dynamique rapide d'échanges d'énergie conduit à la variation ultrarapide de leurs propriétés optiques, accompagnée d’autres effets comme la photoluminescence, l’échauffement hyperlocalisé, la photoémission électronique, la production de radicaux libres, la nano-cavitation. La conception de nanostructures hybrides complexes permet d'adapter les propriétés plasmoniques pour optimiser les applications. Nous avons étudié certaines nanostructures hybrides par spectroscopie d'absorption pompe-sonde large bande et une modélisation dédiée : fibres de silice décorées de NP d’or, NP cœurs-coquilles Au-Ag. Leurs réponses optiques stationnaire et transitoire sont analysées en fonction de la morphologie des NP.Dans les développements évoqués ci-dessus, l’exaltation de champ proche autour des NP plasmoniques joue un rôle clé. Cependant, l’étude de la modulation transitoire du champ proche est limitée par l'incapacité des outils numériques usuels à saisir de faibles variations de la permittivité des NP. Nous mettons en œuvre une méthode FDTD basée sur les paires pole-résidu complexes-conjugués pour pouvoir simuler l’évolution temporelle de la topographie du champ proche plasmonique. Au-delà, le mode LSPR peut être couplé à un mode photonique dans une cavité hybride pour concevoir des fonctionnalités photoniques optiquement contrôlées. Le couplage d'un réseau 2D de nanobâtonnets d'or parallèles avec le mode de défaut d'une cavité d’un cristal photonique 1D est étudié théoriquement. L'anisotropie optique permet de jouer avec plusieurs degrés de liberté comme la polarisation du champ. La modulation ultrarapide de la réponse optique prédite dans de telles nanostructures hybrides ouvre la possibilité de leur optimisation future pour la conception de capteurs résolus en temps
The remarkable properties associated with the localized plasmon resonance (LSPR) in noble metal nanoparticles (NPs) make plasmonics an important topic with multiple applications. When NPs are illuminated by ultrashort laser pulses they undergo a rapid dynamics of energy exchanges which leads to the ultrafast variation of their optical properties, associated with other effects such as broadband photoluminescence, hyperlocalized heat release, electron photoemission, production of reactive oxygen species and nano-cavitation. The design of complex hybrid nanostructures can enable us to tailor the plasmonic properties as to optimize the applications. We have studied some hybrid nanostructures by broadband pump-probe absorption spectroscopy and a dedicated modeling: AuNP-decorated silica fibers and core-shell Au-Ag NPs. Their stationary and transient optical responses are analyzed depending on the NP morphology.In the developments evoked above the enhanced near field around plasmonic NPs plays a key role. However, the study of the ultrafast transient modulation of the near field is limited by the inability of the conventional numerical tools to catch the small variations of the NP permittivity. Here, a complex-conjugate pole-residue pair based FDTD method is successfully implemented to simulate the time-dependence of the plasmonic near-field topography. Beyond, the LSPR mode can be resonantly coupled with a photonic mode in a hybrid microcavity for conceiving optically-controlled photonic functionalities. The coupling of a 2D array of parallel gold nanorods with the defect mode of a 1D photonic crystal cavity is investigated theoretically. The optical anisotropy enables us to play with several degrees of freedom like field polarization. The ultrafast modulation of the optical response that is predicted in such hybrid nanostructures opens the possibility of their future optimization for designing time-resolved sensors

Стилі APA, Harvard, Vancouver, ISO та ін.

20

Asiri, Hamoudi. "Fabtrication of Surface Plasmon Biosensors in CYTOP." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23286.

Повний текст джерела

Анотація:

This thesis describes work carried out on the research, development and implementation of new processes for the fabrication of surface plasmon waveguide biosensors. Fabrication of surface plasmon resonance (SPR) based waveguides embedded in a thick CYTOP cladding with the incorporation of fluidic channels was achieved with improved quality and operability compared to previous attempts. The fabrication flow was modified in key areas including lithography for feature definition, gold evaporation and the upper cladding deposition procedure. The combined result yielded devices with sharper resolution of waveguides, gold surfaces with minimal aberrations, reduced surface roughness and minimization of waveguide deformation due to reduction of solvent diffusion into the lower cladding. The fabricated waveguides consisted of a thin, 35 nm, patterned gold film, embedded in a thick, 18 µm, CYTOP fluoroploymer cladding. The gold devices were exposed by O2 plasma etching through the upper cladding to form fluidic channels for the facilitation of flow of an index matched sensing medium. Optical and physical characterization of devices revealed structures of significantly improved quality over previous attempts, rendering the platform competitive for biosensing applications.

Стилі APA, Harvard, Vancouver, ISO та ін.

21

Schumann, Robert Paul. "Surface plasmon random scattering and related phenomena." Thesis, Connect to title online (Scholars' Bank) Connect to title online (ProQuest), 2009. http://hdl.handle.net/1794/10297.

Повний текст джерела

Анотація:

Typescript. Includes vita and abstract. Includes "Monte Carlo SPP Scattering Simulation Program" (leaves 107-123) Includes bibliographical references (leaves 124-129) Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.

Стилі APA, Harvard, Vancouver, ISO та ін.

22

Tellez, Limon Ricardo. "Light propagation in integrated chains of metallic nanowires : towards a nano-sensing device." Thesis, Troyes, 2014. http://www.theses.fr/2014TROY0039/document.

Повний текст джерела

Анотація:

Les systèmes optiques intégrés ont été largement utilisés dans la détection et la caractérisation de substances biochimiques. Aussi, le développement de nouvelles technologies permettant la fabrication de structures intégrées à l’échelle nanométrique, ouvre un horizon dans la conception d'une nouvelle génération de capteurs biochimiques. Sur la base de plasmons de surface localisés, au cours des dernières années ont été proposés différentes configurations de systèmes optiques pour concentrer le champ électromagnétique dans une petite région de l'espace, ce qui favorise son interaction avec des substances biochimiques. En utilisant la méthode modale de Fourier, dans la présent thèse est présentée une analyse exhaustive de la propagation des modes dans un réseau périodique de nanoparticules métalliques intégrés avec une guide d'ondes diélectrique. Deux géométries des nanoparticules ont été étudiées: des réseaux périodiques de nanofils et de nanocônes métalliques. Il est démontré que pour les nanocônes métalliques le champ optique est fortement exalté au sommet des nanocônes quand ils sont excités à leur résonance LSP via une guide d'onde diélectrique. Pour valider les résultats numériques, on a fabriqué et caractérisé expérimentalement un réseau périodique de nanofils d’or placée sur une guide d’onde à échange d’ions. La caractérisation de l'échantillon a été réalisée dans le champ lointain en mesurant des spectres de transmission et dans le champ proche en utilisant la microscopie en champ proche optique de balayage (NSOM). Les résultats obtenus montrent que les dispositifs intégrés plasmoniques proposées peuvent être appliquées dans la détection de substances biochimiques
Localized surface plasmons (LSP) are used to control and concentrate the electromagnetic field in small volumes of matter. This is a very interesting property in the context of biophotonics. Indeed, it allows an enhancement of the light-matter interaction at the cell scale, or even at a single molecule scale. The technological challenge is to propose optical devices able to efficiently couple light into localized plasmonic modes and to improve the detection of signals resulting from the interaction between the confined light and the analyte under detection.In this thesis work, we theoretically and experimentally study the guiding and confinement properties of light in periodic arrays of metallic nanowires of rectangular and triangular (nanocones) cross section that support localized plasmons. These nanowires are integrated in a photonic circuit that enables an efficient light coupling. The extinction spectra of the plasmonic resonances are directly obtained by analyzing the transmitted light in the device. By making use of the Fourier modal method, we perform an exhaustive theoretical study of the plasmonic Bloch modes that propagate due to the near-field coupling of the localized plasmons resonances. It is demonstrated that for the metallic nanocones, the optical field can be strongly enhanced by a controllable tip effect and remarkably intense

Стилі APA, Harvard, Vancouver, ISO та ін.

23

Huang, Caijin. "Optical nano-antennas : passive properties and active control." Thesis, Dijon, 2010. http://www.theses.fr/2010DIJOS011/document.

Повний текст джерела

Анотація:

Les nano-antennes optiques sont de nouveaux éléments, généralement métalliques, permettant d’améliorer les interactions électromagnétiques entre le rayonnement lumineux et un objet sub-longueur d’onde. Ces dispositifs innovants, fonctionnant dans une gamme de longueur d’onde correspondant au spectre visible et proche infrarouge, répondent à certaines contraintes inhérentes à l’optique lorsque les échelles d’interactions relèvent du nanomètre. En particulier, les propriétés des antennes optiques métalliques sont régies par l’apparition de résonances plasmons qui permettent, d’une part de confiner le champ électromagnétique dans des volumes très inférieurs aux limites imposées par la diffraction, et d’autre part d’exalter fortement les processus optiques à faibles sections efficaces. L’objectif de cette thèse est de comprendre par l’expérience quels sont les paramètres clés qui caractérisent une nano-antenne optique afin d’en contrôler son fonctionnement. Ces paramètres ont été accessibles expérimentalement grâce au développement d’une microscopie adaptée basée sur une illumination diascopique à faible ouverture numérique avec soit une détection coronographique confocale ou conoscopique. Cet appareillage nous a permis de mesurer la capacité d’une antenne optique unique à diffuser un rayonnement lumineux. Les études ont débutées avec des systèmes modèles simples (nanoparticules) pour évoluer vers des antennes couplées (dimères). Par analogie avec le domaine radiofréquences, les paramètres importants d’une antenne optique que sont la plage fréquentielle, le désaccord, le gain et le diagramme de rayonnement ont été définis et mesurés. L’influence des caractéristiques morphologiques de l’antenne sur ces paramètres a complété l’étude. Toujours par comparaison avec les antennes radiofréquences, nous avons introduit le concept de tuner optique. Le principe est de modifier la réponse optique de la charge de l’antenne, c’est-à-dire le milieu dans lequel elle émet son rayonnement. Dans ce but, nous avons utilisé un milieu anisotrope composé des molécules de cristal liquide dont l’orientation de l’ellipsoïde des indices peut être commandée par un champ électrostatique. Le fonctionnement du tuner, c’est-à-dire l’accord de l’antenne à une fréquence de travail, a été démontré pour des antennes optiques couplées
Optical nanoantennas are a new class of optical devices, generally constituted of metal nanoparticles, used for enhancing the interaction between an electromagnetic wave and a nano-scale object. These components are operating in the visible to near infra-red part of the spectrum and are offering solutions for the inherent limitations of optics at the nanometer scale. In particular, the properties of optical antennas are governed by the surface plasmon resonances of the underlying structure. These resonances are associated with a large field confinement, beyond the diffraction limit, and an enhancement of the local electromagnetic response that is used to amplify weak optical processes. The objective of this doctoral thesis is to understand by an experimental approach what are the key parameters characterizing an optical antenna with the aim to control its operation. Through the development of an original microscopy based on a low numerical aperture diascopic illumination and a subsequent spatial filtering, the scattering characteristics of a single optical nano-antenna were successfully measured. Our approach was first tested with simple model antennas (nanoparticles) before investigating multi-element coupled antennas (dimers). In analogy to radiofrequency theory, we have defined and measured important antenna characteristics: operating frequency, detuning factor, gain and emission diagram. We have studied the influence of the morphology of the antenna on these characteristics. Continuing the comparison with microwave antennas, we have introduced the concept of an optical tuner. The operating principle is to modify the medium in which the antenna is emitting its radiation i.e. the load of the device. To this aim, we have employed anisotropic liquid crystal molecules. With this load medium, the orientation of the anisotropy can be controlled by a static electric field. The operation of the optical tuner, i.e. tuning of the antenna to a broadcasting frequency, is demonstrated for electromagnetically coupled antennas

Стилі APA, Harvard, Vancouver, ISO та ін.

24

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

Повний текст джерела

Анотація:

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

Стилі APA, Harvard, Vancouver, ISO та ін.

25

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.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

26

Béland, Paul. "An Optical Biosensor Towards Urinary Tract Infection Diagnosis." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32881.

Повний текст джерела

Анотація:

We explore a new laboratory technique in the field of urinalysis promising a combination of speed and selectivity in support of urinary tract infection diagnosis. Laboratory experimentation demonstrates long range surface plasmon polaritons (LRSPP) waveguides as a useful biosensor to selectively detect gram negative bacteria or gram positive bacteria in human urine. The biosensor can detect bacteria at concentration of 105 CFU/ml, the internationally recommended threshold for diagnostic of urinary tract infection (UTI). Using a negative control solution at bacterial concentration 1000x higher than the targeted bacteria in urine with a weak concentration of constituents, the power ratio between the negative control signals to the target bacteria signal is measured to be 5.4. Thus we report a conclusive demonstration of the LRSPP waveguide biosensor selectivity to the gram of bacteria in human urine. In addition, the biosensor may prove useful as an alternative urinalysis test method to determine the urine specific gravity, to estimate proteinuria, and to detect biofilm formation on surfaces.

Стилі APA, Harvard, Vancouver, ISO та ін.

27

STEIJN, KIRK WILLIAM. "COUPLING AND PROPAGATION OF SURFACE PLASMONS IN THE FAR-INFRARED (NEAR-MILLIMETER WAVES, SUB-MILLIMETER WAVES)." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183973.

Повний текст джерела

Анотація:

This work describes a study of the propagation properties of a modified surface plasmon mode, and of the coupling properties of that mode using a grating coupler. The surface plasmon, a polariton involving coupling of electromagnetic waves to the plasma oscillations of a metal, is modified by the application of a dielectric overlayer to the interface between the metal and air. In the far infrared region of the electromagnetic spectrum, the overlayer causes dramatic changes in several properties of the mode, which can be verified by measuring the propagation length of the mode. Measurements at a wavelength of 118.8 μm of the propagation length as a function of the thickness of a polycrystalline silicon overlayer on silver showed that the mode has the expected properties. They also indicated that the Drude model of the dielectric function of the silver is valid at 118.8 μm, even when using established Drude parameters, which are based on measurements in the visible and near infrared region of the electromagnetic spectrum. The coupling study measured the fundamental coupling parameters, also at a wavelength of 118.8 μm, for coupling via a grating between free-space waves and the surface plasmon, and measured the effect of the overlayer on these parameters. Efficient coupling was achieved, but a theoretical treatment of the coupling system proved to be beyond the scope of first-order grating-coupler theory. This was true despite the fact that the grating amplitude was a small fraction of the wavelength, a common criterion for the application of such a theory. Several possible reasons for the breakdown of the theory were considered, but definite answers require additional experiments. The most prominent possibilities are the shape factor, and the depth of the grating compared to the penetration depth of the fields into the metal. Though not all the data is completely explained, the studies herein demonstrate that the overlayer eliminates many of the deficiencies which limit the generation and control of far-infrared surface plasmons.

Стилі APA, Harvard, Vancouver, ISO та ін.

28

Hewageegana, Prabath. "Theory of Electronic and Optical Properties of Nanostructures." Digital Archive @ GSU, 2008. http://digitalarchive.gsu.edu/phy_astr_diss/27.

Повний текст джерела

Анотація:

"There is plenty of room at the bottom." This bold and prophetic statement from Nobel laureate Richard Feynman back in 1950s at Cal Tech launched the Nano Age and predicted, quite accurately, the explosion in nanoscience and nanotechnology. Now this is a fast developing area in both science and technology. Many think this would bring the greatest technological revolution in the history of mankind. To understand electronic and optical properties of nanostructures, the following problems have been studied. In particular, intensity of mid-infrared light transmitted through a metallic diffraction grating has been theoretically studied. It has been shown that for s-polarized light the enhancement of the transmitted light is much stronger than for p-polarized light. By tuning the parameters of the diffraction grating enhancement can be increased by a few orders of magnitude. The spatial distribution of the transmitted light is highly nonuniform with very sharp peaks, which have the spatial widths about 10 nm. Furthermore, under the ultra fast response in nanostructures, the following two related goals have been proved: (a) the two-photon coherent control allows one to dynamically control electron emission from randomly rough surfaces, which is localized within a few nanometers. (b) the photoelectron emission from metal nanostructures in the strong-field (quasistationary) regime allows coherent control with extremely high contrast, suitable for nanoelectronics applications. To investigate the electron transport properties of two dimensional carbon called graphene, a localization of an electron in a graphene quantum dot with a sharp boundary has been considered. It has been found that if the parameters of the confinement potential satisfy a special condition then the electron can be strongly localized in such quantum dot. Also the energy spectra of an electron in a graphene quantum ring has been analyzed. Furthermore, it has been shown that in a double dot system some energy states becomes strongly localized with an infinite trapping time. Such states are achieved only at one value of the inter-dot separation. Also a periodic array of quantum dots in graphene have been considered. In this case the states with infinitely large trapping time are realized at all values of inter-dot separation smaller than some critical value.

Стилі APA, Harvard, Vancouver, ISO та ін.

29

Bai, Fan. "Investigation of optical properties of one-dimensional nanostructures with engineerable heliciity and surface modification." HKBU Institutional Repository, 2017. https://repository.hkbu.edu.hk/etd_oa/437.

Повний текст джерела

Анотація:

In this work, the optical properties of two kinds of one-dimensional (1D) nanomaterials, mesoporous silicon nanowires (mpSiNWs) and plasmonic nanospirals (NSs), were studied. These emerging nanomaterials are of great interest because of their fundamental structure-derived properties and potential practical applications. Four aspects of these materials were analyzed in this work. First, although the fabrication mechanism of mpSiNWs has been studied previously via metal-assisted chemical etching, the porosification-induced disturbance to the etching direction, which plays a vital role in controlling the surface crystallinity of mpSiNWs, has not been characterized. In Chapter 2, I discuss the porosification etching mechanism of n-Si(111), which proceeds along the intrinsic back bond etching direction of [111] at room temperature. The porosification substantially weakens the back bonds under the sinking particles, resulting in the deviation of etching from [111]. The preferred direction of etching changes to that with a small angle α, because the direction-switching barrier increases with α and intrinsic back-bond etching is thermodynamically preferential. Second, mpSiNWs typically generate red photoluminescence (PL), but the PL mechanism is still under debate. A laser was used to oxidize the surfaces of mpSiNWs and tune the PL from red to greenish-blue (GB), as described in Chapter 3. The laser oxidation was tuned as a function of laser power, and a complex model of the laser-induced surface modification was proposed to account for the laser-power and post-annealing effect. The laser-induced modification of the PL of mpSiNWs may be useful for data encryption. Third, the fabrication of plasmonic NSs and the study of their optical activities are in their infancy. In Chapter 4, I describe the use of glancing-angle deposition (GLAD) to fabricate silver NSs (AgNSs) with controllable helicity and demonstrate that AgNSs have intrinsic optical responses that originate from their structural helicity. The optical activity of an AgNSs dispersion was characterized by circular dichroism (CD), and systematic engineering of the helicity revealed that their UV and visible optical activities have two different origins. Fourth, physical limits prohibit the sensitive differentiation of enantiomers. In Chapter 5, I describe the grafting of chiral molecules onto AgNSs, which dramatically enhanced the differentiation of L- and D-glutathione (GSH). AgNSs have very strong optical activities that are weakened by GSH adsorption. The severity of the chiroptical weakening effect varies with the absolute configuration of GSH, resulting in enantiomeric differentiation with an anisotropic g-factor of approximately 0.5. This chiral nanoplasmon-induced anisotropy g-factor is superior by 2 to 4 orders of magnitude to those obtained with other methods and about one-fourth of the theoretical value. This proposed method can be adapted to differentiate chiral drugs, which is highly desirable in the pharmaceutical industry for the production of single-enantiomer drugs.

Стилі APA, Harvard, Vancouver, ISO та ін.

30

Skjonnemand, Karl. "The optical and structural characterisation of ultra-thin films." Thesis, Cranfield University, 2000. http://dspace.lib.cranfield.ac.uk/handle/1826/10739.

Повний текст джерела

Анотація:

Chloride, bromide, pyridinium and quinolinium homologues of 4-(N- hexadecylpyridinium-4-ylmethylidene-amino)-2,6-dichlorophenolate have been investigated in solution, Langmuir and Langmuir-Blodgett films. Techniques including spectroscopy, surface potential measurement, quartz crystal microbalance, surface plasmon resonance, atomic force microscopy, reectometry and X-ray diffraction have been used to characterise these molecular systems. In solution, solvatochroism was observed and Benisi-Hildebrand analysis revealed dimeric aggregation. Langmuir monolayers were compressed at the air/water interface and chromophore rotation was observed by surface potential measurement. Langmuir- Blodgett monolayers showed lm-thickness dependence on the deposition-pressure. Monolayer thicknesses between 6-24Ä were measured using SPR and molecular areas between 40-l25Ä2 were measured using a quartz crystal microbalance. Both the molecular/s/area)and monolayer thicknesses were deposition-pressure dependent. The high tilt phases were visually distinguishable from the low tilt phases using atomic force microscopy, The compounds showed phase behaviour that was predominantly alike for the bromide and chloride homologues but different for the pyridinium and quinolinum homologues. Multilayer Y-type films of the merocyanine dyes were analysed using reectometry and deposition-pressure dependent thicknesses were found. Alternate layer structures of NLO-active hemicyanine amphiphiles were used to achieve homogeneous. orientation ordering using active and inactive spacer layers. Ordering was achieved but the optical efficiency was reduced by high proportions of inactive material and interlayer dipole formation. Double chained hemicyanine molecules were used to form Z-type structures and subsequent layers were found to significantly interdigitate. Different chain lengths were found to interdigitate by the length of the shortest chain. Gas detection experiments were undertaken on the quinolinium, dichloro merocyanine using three optical geometries. The absorption method showed slow switching and poor sensitivity. The Kretschmann SPR geometry showed high sensitivity and rapid switching. The grating SPR geometry showed rapid switching but was less sensitive than the ATR method. Protonation of the monolayers was investigated using hydrochloric acid gas, acetic acid vapour and stearic acid immobilised within the lm.

Стилі APA, Harvard, Vancouver, ISO та ін.

31

Yeatman, Eric Morgan. "Surface plasmon applications : microscopy and spatial light modulation." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47722.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

32

Karar, Ayman A. "Surface plasmons for enhanced metal-semiconductor-metal photodetectors." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2013. https://ro.ecu.edu.au/theses/593.

Повний текст джерела

Анотація:

Surface Plasmon Polaritons (SPPs) are quantized charge density oscillations that occur when a photon couples to the free electron gas of the metal at the interface between a metal and a dielectric. The extraordinary properties of SPP allow for sub-diffraction limit waveguiding and localized field enhancement. The emerging field of surface plasmonics has applied SPP coupling to a number of new and interesting applications, such as: Surface Enhanced Raman Spectroscopy (SERS), super lenses, nano-scale optical circuits, optical filters and SPP enhanced photodetectors. In the past decade, there have been several experimental and theoretical research and development activities which reported on the extraordinary optical transmission through subwavelength metallic apertures as well as through periodic metal grating structures. The use of SPP for light absorption enhancement using sub-wavelength metal gratings promises an increased enhancement in light collection efficiency of photovoltaic devices. A subwavelength plasmonic nanostructure grating interacts strongly with the incident light and potentially traps it inside the subsurface region of semiconductor substrates. Among all photodetectors, the Metal-Semiconductor-Metal photodetector (MSM-PD) is the simplest structure. Moreover, due to the lateral geometry of the MSM-PDs, the capacitance of an MSM-PD is much lower than capacitances of p-i-n PDs and Avalanche PDs, making its response time in the range of a few tens of picoseconds for nano-scale spacing between the electrode fingers. These features of simple fabrication and high speed make MSM-PDs attractive and essential devices for high-speed optical interconnects, highsensitivity optical samplers and ultra-wide bandwidth optoelectronic integrated circuits (OEIC) receivers for fibre optic communication systems. However, while MSM-PDs offer faster response than their p-i-n PD and avalanche PD counterparts, their most significant drawbacks are the high reflectivity of the metal fingers and the very-low light transmission through the spacing between the fingers, leading to very low photodetector sensitivity. This thesis proposes, designs and demonstrates the concept of a novel plasmonicbased MSM-PD employing metal nano-gratings and sub-wavelength slits. Various metal nano-gratings are designed on top of the gold fingers of an MSM-PD based on gallium arsenide (GaAs) for an operating wavelength of 830 nm to create SPP-enhanced MSM-PDs. Both the geometry and light absorption near the designed wavelength are theoretically and experimentally investigated. Finite Difference Time Domain (FDTD) simulation is used to simulate and design plasmonic MSM-PDs devices for maximal field enhancement. The simulation results show more than 10 times enhancement for the plasmonic nano-grating MSM-PD compared with the device without the metal nano-gratings, for 100 nm slit difference, due to the improved optical signal propagation through the nano-gratings. A dual beam FIB/ SEM is employed for the fabrication of metal nano-gratings and the sub-wavelength slit of the MSM-PD. Experimentally, we demonstrate the principle of plasmonics-based MSM-PDs and attain a measured photodetector responsivity that is 4 times better than that of conventional single-slit MSM-PDs. We observe reduction in the responsivity as the bias voltage increases and the input light polarization varies. Our experimental results demonstrate the feasibility of developing high-responsivity, low bias-voltage high-speed MSM-PDs. A novel multi-finger plasmonics-based GaAs MSM-PD structure is optimized geometrically using the 2-D FDTD method and developed, leading to more than 7 times enhancement in photocurrent in comparison with the conventional MSM-PD of similar dimensions at a bias voltage as low as 0.3V. This enhancement is attributed to the coupling of SPPs with the incident light through the nano-structured metal fingers. Moreover, the plasmonic-based MSM-PD shows high sensitivity to the incident light polarization states. Combining the polarization sensitivity and the wavelength selective guiding nature of the nano-gratings, the plasmonic MSM-PD can be used to design high-sensitivity polarization diversity receivers, integrating polarization splitters and polarization CMOS imaging sensors. We also propose and demonstrate a plasmonic-based GaAs balanced metalsemiconductor- metal photodetector (B-MSM-PD) structure and we measure a common mode rejection ratio (CMRR) value less than 25 dB at 830nm wavelength. This efficient CMRR value makes our B-MSM-PD structure suitable for ultra-high-speed optical telecommunication systems. In addition, this work paves the way for the monolithic integration of B-MSM-PDs into large scale semiconductor circuits. This thesis demonstrates several new opportunities for resonant plasmonic nanostructures able to enhance the responsivity of the MSM-PD. The presented concepts and insights hold great promise for new applications in integrated optics, photovoltaics, solidstate lighting and imaging below the diffraction limit. In Chapter 10 we conclude this thesis by summarizing and discussing some possible applications and future research directions based on SPP field concentration.

Стилі APA, Harvard, Vancouver, ISO та ін.

33

Torrance, David. "Influence of the Local Dielectric Environment and its Spatial Symmetry on Metal Nanoparticle Surface Plasmon Resonances." Honors in the Major Thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1195.

Повний текст джерела

Анотація:

This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.
Bachelors
Sciences
Physics

Стилі APA, Harvard, Vancouver, ISO та ін.

34

Nguyen, Thi Tuyet Mai. "Elaboration and optical properties of thermosensitive plasmonic hybrid nanostructures." Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCC285.

Повний текст джерела

Анотація:

La conception de nanomateriaux hybrides multifonctionnels est un champ de recherche en plein essor. Notamment, la combinaison de polymères thermosensibles et de nanoparticules d'or (GNPs) offre des perspectives prometteuses pour l'élaboration de matériaux à grande valeur ajoutée pour des applications dans le domaine des capteurs, du biomédical et de la catalyse. Dans ce travail de thèse, nous avons élaboré des nanostructures hybrides combinant nanoparticules d'or et poly(N-isopropylacrylamide) (PNIPAM), en s'appuyant sur des techniques de lithographies et de polymérisation radicalaire contrôlée. Grâce à ces deux techniques, il a été possible de faire varier à la fois le degré d'anisotropie des nanoparticules d'or et l'épaisseur des chaînes de PNIPAM, de façon parfaitement contrôlée. L'influence de ces deux paramètres sur la sensibilité des nanostructures plasmoniques à leur environnement local et plus particulièrement à des changements de température a ainsi pu être étudiée. De plus, en utilisant les nanoparticules d'or comme nanosources de chaleur, nous avons pu induire localement des élévations de température très rapides et déterminer les échelles de temps du processus de transition de phase des brosses de PNIPAM greffées. Dans un deuxième temps, nous avons cherché à exploiter ces structures hybrides stimulables pour la détection de molécules par SERS ou pour sonder l'isomerisation de molécules photochromes d'azobenzene, par spectroscopie UV-visible. Dans un dernier temps, nous avons proposé une nouvelle stratégie de greffage de couches organiques sur les nanostructures d'or, spatialement sélective, induite par plasmon. Le greffage de groupes aryles dérivant de sels de diazonium se produit spécifiquement dans les régions d'exaltation maximale du champ électromagnétique autour des GNPs. Cette nouvelle approche ouvre de nombreuses perspectives pour le confinement à l'échelle nanométrique de couches de polymères greffées sur des nanostructures plasmoniques
Driven by the search for hybrid multifunctional nanomaterials with interesting and unique properties, we have considered the association of thermoresponsive pNIPAM with gold nanoparticles (GNPs), which ideally combine the responsiveness of pNIPAM with the optical, catalytic or photothermal properties of GNPs. In this PhD dissertation, we addressed strong synergies between GNPs and PNIPAM in hybrid GNP@PNIPAM nanostructures, obtained from the grafting of PNIPAM brushes on lithographie GNPs arrays. Firstly, the hybrid nanostructures including gold nanorod (GNRs) arrays coated by pNIPAM allowed us to investigate properly the influence of the GNPs anisotropy and the polymer thickness on the sensitivity to the local environment. The optimization of the GNR's aspect ratio r and the pNIPAM thickness, to provide a maximum of LSP shift upon a change in temperature,is obtained for r'-2. 4-2. 6 and hPNIPAM —25 nm, respectively. Secondly, such hybrid nanostructures allowed us to measure the phase transition time of pNIPAM brushes, 160±20 Ils for a 30 nm pNIPAM layer. Particularly, we used the pNIPAM brushes as a dynamic linker in order to control the coupling of plasmonic nanoparticles and the sensitive detection of Nile blue A molecules by SERS. Such hybrid nanostructures were also applied to probe the isomerization of azobenzene derived molecules by UV-visible spectroscopy. Interestingly, we developed a new strategy for the selective plasmon-mediated chemical grafting of aryl layers derived from diazonium salts on gold nanostripe arrays. This grafting occurs specifically in the regions of maximum field enhancement of GNPs. In perspective, this strategy is expected to allow us controlling the grafting of pNIPAM brushes, and thus the binding of analyte molecules to selected locations on the GNP surface with well-defined near-field enhancement factor for quantitative SERS measurements

Стилі APA, Harvard, Vancouver, ISO та ін.

35

Jorgenson, Ralph Corleissen. "Surface plasmon resonance based bulk optic and fiber optic sensors /." Thesis, Connect to this title online; UW restricted, 1993. http://hdl.handle.net/1773/5996.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

36

Hernández–Martínez, Pedro Ludwig. "Optical Properties of Nanoparticles and Nanowires: Exciton–Plasmon Interaction and Photo–Thermal Effects." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1282315341.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

37

Maximino, Fabio Lombardi. "Caracterização de plasmons de superfície em filmes de metais nobres através de tunelamento ótico." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-15052012-154158/.

Повний текст джерела

Анотація:

Os metais nobres são admirados desde as culturas mais antigas por sua capacidade de refletir a luz. Com os desenvolvimentos na área da nanotecnologia se pode entender um pouco mais sobre a interação entre a luz e estes metais. Devido a esta interação foi criada a Plasmônica e a partir dela começaram os estudos acerca dos plasmons de superfície (SP). Estes estudos vêm gerando inúmeros desenvolvimentos nas pesquisas de gravação magneto-ótica, microscopia, detectores moleculares biológicos entre outras. Como os SPs são ondas evanescentes, eles precisam ser observados em campo próximo. Com o intuito de observar e compreender a propagação destes SPs foi utilizado um microscópio ótico de varredura em campo próximo (SNOM). Para isto, o SNOM foi adaptado para operar em modo de transmissão. A sonda do SNOM serviu de coletora de luz para que a partir de imagens óticas em amostras de Ag e Au pudéssemos caracterizar a propagação destes SPs na superfície do material e também a sua dependência com a distância de detecção. Os resultados mostraram que a propagação do SP é maior que 70m e a intensidade do SP na superfície do metal depende fortemente da rugosidade da amostra e de possíveis defeitos. Foi possível ainda estimar a que distância a partir da superfície da amostra, em que o SP decai para 1/e. Este resultado está de acordo com o esperado teoricamente, que prevê para a distância de propagação do SP, o valor de 420nm. Através do SP ainda foi possível analisar defeitos existentes na amostra. E pelas imagens topográficas do SNOM também foi possível observar os grãos de Ag e Au da amostra. Em posse destes resultados pudemos concluir que o SNOM é uma ótima ferramenta para a análise dos plasmons de superfície.
The noble metals are largely admired since ancient cultures because of its capability to reflect light. With the development of nanotechnology it is possible now to understand the interaction between these metals and light. Due to this strong interaction, the Plasmonic area was created and the studies on Surface Plasmons(SP) started. These studies are responsible for important new developments in magneto-optical recording, new optical microscopy apparatus, molecular biological sensors, among others. As SPs are evanescent waves, they need to be observed in near-field optics. For the observation and study of the propagation of these SPs a scanning near-field optical microscope (SNOM) was used. The SNOMs probe was used in collection mode so that we could characterize the propagation of SPs in the material surface and the dependence with the distance of detection in air, for thin films of Ag and Au. The results showed that the propagation of the SP inside the metallic film is beyon 70m. And the SPs intensity in the metal surface is strongly dependent on the roughness of the sample. It was also possible to estimate the distance from the samples surface the SP decay to 1/e. Our measurements agree to the theoretical calculation of 420nm for this distance. The SP made it possible to analyze existing defects on the sample. Furthermore, with the SNOM topographical images it was also possible to observe the grains of the policrystalline Ag and Au samples. From these results we could conclude that the SNOM is a very useful tool for the analysis of surface plasmons in thin films.

Стилі APA, Harvard, Vancouver, ISO та ін.

38

Rodriguez, Kenneth Ralph. "The extraordinary infrared transmission of metal microarrays for enhanced absorption spectroscopy of monolayers, nanocoatings, and catalytic surface reactions." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1189549712.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

39

Al-Aridhee, Tahseen. "Numerical study of optical properties of single and periodic nanostructures : from nanoantennas to enhanced transmission metamaterials." Thesis, Besançon, 2016. http://www.theses.fr/2016BESA2004/document.

Повний текст джерела

Анотація:

L ’intérêt des nano-particules pour le domaine de l ’optique visible a été suscité lors du premier rapport rédigé par Faraday en 1857 et qui a initié les bases de la production de nanoparticules métalliques en vue de leur propriété optiques inattendues (coloration des solutions). Plus récemment, le contrôle et le guidage de la lumière basés sur l’excitation de résonance plasmon dans les nanostructures a permis beaucoup d’applications liées à la vie quotidienne et impliquant la lumière. La résonance plasmonique de structures métalliques estun phénomène essentiel qui conduit à des propriétés optiques uniques à travers l’interaction de la lumière avecles électrons libres du métal. L’excitation de la résonance plasmon localisé (LSPR) permet d’exalter localement l’énergie électromagnétique comme dans le cas des nano-antennes mais aussi d’acheminer la lumière à travers des canaux de dimensions sub-l sur de grandes distances distances grâce à l’excitation du Plasmonde Surface Propagatif (PSP). Au cours de cette thèse, nous avons étendu un algorithme existant afin de calculer la réponse optique (sections efficaces de diffusion et d’absorption) de NPs ayant une forme géométrie quelconque. Ce type de NP anisotrope (vis-à-vis de la polarisation incidente) peut présenter à la résonance plasmonique une section efficace de diffusion 25 fois supérieure à celle géométrique. De plus, une étude systématique importante a été effectuée afin d’optimiser la géométrie de tels Nps.En ce qui concerne la PSP qui est impliqué dans la transmission exaltée à travers les matrices d’ouvertures annulaires AAA, nous avons entrepris une étude systématique des propriétés de l’excitation du mode particul particulier sans coupure de ces nano - guides. Il s’agit du mode Transverse Electrique et Magnétique (TEM). Une étude numérique complète est alors effectuée pour correctement concevoir la structure avant qu’elle ne soit expérimentalement fabriquée et caractérisée. Pour palier certaines contraintes expérimentale, une structure inclinée est proposée et étudiée dans le cas d’un métal parfaitement conducteur. Nous avons démontrée numériquement et analytiquement certaines propriétés intrinsèques de la structure montrant un coefficient de d’au moins 50% d’un faisceau incident non polarisé indépendamment des conditions d’éclairage (polarisation,angle et plan d’incidence). Lorsque le mode TEM est excité, le flux laminaire de l’énergie à travers la structure présente une déviation géante sur de très petites distances inférieures à la longueur d’onde. Les résultats présentés dans cette thèse pourraient être considérés comme une contribution importante à la compréhension du phénomène de transmission exaltée basé sur l’excitation de ce type de mode guidé
The release of the rst report by Faraday in 1857 set the foundation of the production of metal nanoparticlesand their unexpected optical properties (coloring). More recently, controlling and guiding light via plasmonicresonance in nanostructures enable a lot of applications affecting everyday life that involves light. Plasmonresonance of metallic structures is a key phenomenon that allows unique optical properties through the interactionof light with the free electrons of the metal. The excitation of Localized Surface Plasmon Resonance(LSPR) leads to turn-on large local enhancements of electromagnetic energy as within antennas or to routelight as waveguide to desired region with high transmission through the excitation of Propagating SurfacePlasmon (PSP). During this thesis, we have developed an existing algorithm in order to calculate the opticalresponse of NPs of any shape. We have especially determined the localized energy enhancement factor interm of optical response of nano-antenna. This anisotropic (polarization dependent) NPs type can feature, atplasmon resonance, scattering efciency factor higher than 25. Moreover, an important systematic study hasbeen performed in order to optimize design of such NPs.Concerning the PSP that are involved in the enhanced transmission through Annular Aperture Arrays (AAAs),we systematically study the properties of the excitation of the peculiar Transverse ElectroMagnetic (TEM) guidedmode inside such nano-apertures. A complete numerical study is performed to correctly design the structurebefore it is experimentally characterized. For reasons associated to fabrication constraints and efciency,a slanted AAA made in perfectly conducting metal is proposed and studied. We numerically and analyticallydemonstrate some intrinsic properties of the structure showing a transmission coefcient of at least 50%ofan un-polarized incident beam independently of the illumination configuration (polarization, angle, and planeof incidence). At the TEM peak transmission, the laminar flow of the energy through the structure can exhibitgiant deviation over very small distances ( ). The results presented in this thesis could be considered as animportant contribution to the understanding of the enhanced transmission phenomenon based on the excitationof guided modes

Стилі APA, Harvard, Vancouver, ISO та ін.

40

Wang, Feng. "Modes, Excitation and Applications of Plasmonic Nano-apertures and Nano-cavities." Kent State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=kent1348588159.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

41

Rusina, Anastasia. "Optical and Terahertz Energy Concentration on the Nanoscale in Plasmonics." Digital Archive @ GSU, 2009. http://digitalarchive.gsu.edu/phy_astr_diss/36.

Повний текст джерела

Анотація:

We introduce an approach to implement full coherent control on nanometer length scales. It is based on spatiotemporal modulation of the surface plasmon polariton (SPP) fields at the thick edge of a nanowedge. The SPP wavepackets propagating toward the sharp edge of this nanowedge are compressed and adiabatically concentrated at a nanofocus, forming an ultrashort pulse of local fields. The profile of the focused waveform as a function of time and one spatial dimension is completely coherently controlled. We establish the principal limits for the nanoconcentration of the terahertz (THz) radiation in metal/dielectric waveguides and determine their optimum shapes required for this nanoconcentration. We predict that the adiabatic compression of THz radiation from the initial spot size of vacuum wavelength R λ 300 μm 0 0 ≈ ≈ to the unprecedented final size of R = 100 − 250 nm can be achieved, while the THz radiation intensity is increased by a factor of 10 to 250. This THz energy nanoconcentration will not only improve the spatial resolution and increase the signal/noise ratio for THz imaging and spectroscopy, but in combination with the recently developed sources of powerful THz pulses, will allow the observation of nonlinear THz effects and a variety of nonlinear spectroscopies (such as two-dimensional spectroscopy), which are highly informative. This should find a wide spectrum of applications in science, engineering, biomedical research and environmental monitoring. We also develop a theory of the spoof plasmons propagating at the interface between a dielectric and a real conductor. The deviation from a perfect conductor is introduced through a finite skin depth. The possibilities of guiding and focusing of spoof plasmons are considered. Geometrical parameters of the structure are found which provide a good guiding of such modes. Moreover, the limit on the concentration by means of planar spoof plasmons in case of non-ideal metal is established. These properties of spoof plasmons are of great interest for THz technology.

Стилі APA, Harvard, Vancouver, ISO та ін.

42

Moreaud, Laureen. "Synthèse, auto-assemblage et caractérisation d'architectures colloïdales hybrides plasmons-émetteurs." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30193.

Повний текст джерела

Анотація:

Cette thèse propose plusieurs approches visant à contrôler la structure d'assemblages hybrides depuis la synthèse des éléments jusqu'à l'auto-organisation et en étudie les propriétés optiques émergentes. Dans une première partie, nous montrons que ce couplage plasmon-émetteur peut être dirigé de deux manières : soit en fonctionnalisant des nanoparticules d'or avec un ligand ayant une fonction permettant de reconnaitre et immobiliser les émetteurs, soit par la création d'un échafaudage de biomolécules portant des sites de greffage des particules fluorescentes et plasmoniques. Dans le premier cas, une synthèse de prismes d'or en présence de protéines artificielles, éventuellement biotinylées, recouvrant leur surface est réalisée. La taille et la forme des prismes déterminent les propriétés spectrales souhaitées des résonances plasmons. Leur sensitivité élevée à une variation de leur environnement diélectrique (300 nm/RIU) a permis la détection de streptavidine sur prisme individuel. Alternativement, l'ingénierie d'une paire de protéines artificielles dont la forte interaction mutuelle déclenche une précipitation spontanée. Une caractérisation par cryo-microscopie électronique à transmission (cryo-TEM) et par diffusion des rayons X montre la formation précise de superhélices tubulaires de 5,8 nm de diamètre et plusieurs microns de long. Les amino-acides de ces protéines pourront être modifiés pour greffer des particules différentes. La deuxième partie de ce manuscrit porte sur une nouvelle synthèse, la caractérisation structurale et les propriétés photo-physiques de clusters d'or Aun avec 4 = n = 25. Ceux-ci sont rendus stables, en solutions aqueuses, par fonctionnalisation avec des thiols pegylés à fonction terminale, dont la biotine. La fluorescence blanche sous excitation large bande et un rendement quantique élevé (jusqu'à 27 %) font de ce mélange Aun des émetteurs prometteurs pour les structures hybrides. Ces Aun-biotine, mais aussi des nanodiamants biotinylés, ont été fixés sur les prismes d'or protéinés ci-dessus. Les protéines en surface des prismes permettent de maîtriser localement et spécifiquement le greffage des émetteurs à 5 nm de la surface d'or. La dernière partie de cette thèse est consacrée à l'étude des propriétés optiques des structures plasmoniques seules puis couplées à des émetteurs. Une comparaison des images hyperspectrales de diffusion en champ sombre et de cathodoluminescence en TEM, adossée à une étude numérique combinant la méthode dyadique de Green et celle des éléments finis, permet d'identifier les modes plasmons brillants et sombres auxquels se couplent les photons émis par les fluorophores, en fonction de leur position
This thesis proposes several approaches to control the structure of hybrid assemblies from element synthesis to self-organization and studies their emerging optical properties. In the first part we show that we can control the coupling in two ways. Either by functionalizing gold nanoparticles with a ligand able to recognize and immobilize the emitters or by creating a scaffolding biomolecule carrying fluorescent and plasmonic particle grafting sites. In the first case, a synthesis of gold prisms in the presence of artificial proteins, possibly biotinylated, covering their surface is carried out. The size and shape of the prisms determine the desired spectral properties of the plasmon resonances. Their high sensitivity to a variation of their dielectric environment (300 nm / RIU) allowed the detection of streptavidin on an individual prism. Alternatively, the engineering of a pair of artificial proteins whose strong mutual interaction triggers spontaneous precipitation. Transmission electron cryo-microscopy (cryo-TEM) and X-ray scattering characterization show the precise formation of tubular supercoils 5.8 nm in diameter and several microns in length. The amino acids of these proteins can be modified to graft different particles. The second part of this manuscript deals with a new synthesis, structural characterization, and photo-physical properties of Aun gold clusters with 4 = n = 25. These are made stable, in aqueous solutions, by functionalization with thiols. terminal function pegylates, including biotin. White fluorescence under broadband excitation and high quantum efficiency (up to 27%) make this mixture a promising emitter for hybrid structures. These Aun-biotin, but also biotinylated nanodiamonds, were attached to the protein gold prisms above. The proteins on the surface of the prisms make it possible to control locally and specifically the grafting of emitters at 5 nm from the gold surface. The last part of this thesis is devoted to the study of the optical properties of plasmonic structures alone then coupled to emitters. A comparison of hyperspectral images of dark-field scattering and cathodoluminescence in TEM, backed by a digital study combining Green's dyadic method and that of the finite elements, makes it possible to identify the bright and dark plasmons modes to which the photons emitted by fluorophores, depending on their position

Стилі APA, Harvard, Vancouver, ISO та ін.

43

Bender, William John Havercamp. "A chemical sensor based on surface plasmon resonance on surface modified optical fibers." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40097.

Повний текст джерела

Анотація:

A sensor is described which utilizes the phenomenon of surface plasmon resonance to detect changes in refractive index of chemical or biochemical samples applied to a surface modified optical fiber. The sensor is constructed by polishing a short section of the lateral surface of an optical fiber to its evanescent field surrounding the fiber core. One or more thin films are applied to the polished section of the fiber to produce the sensing element. One of the films is the metal silver, which acts as the support for the surface plasmon. Under the proper conditions, TM polarized energy propagating in the fiber can be coupled to a surface plasmon electromagnetic mode on the metal film. This coupling depends on the wavelength, the nature of the fiber, the refractive index and thickness of the thin films applied to the fiber, and the refractive index of a chemical sample in contact with the modified surface. The fiber to plasmon coupling is seen as a large attenuation of the light reaching the distal terminus of the fiber.
Ph. D.

Стилі APA, Harvard, Vancouver, ISO та ін.

44

Tang, Feng. "Micro SERS sensors based on photonic-plasmonic circuits and metallic nanoparticles." Thesis, Troyes, 2017. http://www.theses.fr/2017TROY0020/document.

Повний текст джерела

Анотація:

La spectroscopie Raman exaltée de surface (SERS) est largement utilisée comme un outil non-intrusif et sans marquage pour identifier les empreintes spectrales moléculaires dans des applications comme la pharmacologie, la salubrité des aliments, etc. Cette thèse présente un micro-capteur SERS basé sur un guide d'ondes hybride constitué de fentes métalliques (Au/Al) et de rubans diélectriques (Si3N4) et sur une méthode pour promouvoir la capacité de détection SERS en plaçant des nanoparticules métalliques dans la fente du capteur. L'étude théorique du capteur est principalement menée par la méthode des différences finies dans le domaine temps en trois dimensions (3D-FDTD) qui fournit la réponse électromagnétique à large bande des nanostructures métalliques. Les facteurs d'exaltation du capteur sont estimés par l’approximation |E|4. Les expériences sont basées principalement sur la fabrication de fentes métalliques, qui est réalisée par la lithographie à faisceau d'électrons (EBL), et sur la caractérisation de la capacité de détection SERS des capteurs. Les résultats montrent que les signaux Raman donnés par les capteurs SERS sont détectables. Les nanoparticules métalliques, qui sont situées dans le capteur, peuvent améliorer considérablement la capacité de détection SERS. En combinant le capteur SERS avec les éléments photoniques et électroniques, un système de détection SERS entièrement intégré sur une puce peut être développé dans un proche avenir pour des détections SERS portables et stables
Surface-enhanced Raman spectroscopy (SERS) is widely used as a non-intrusive and label-free tool to identify the molecular spectral fingerprints in pharmacology, biology, etc. This thesis presents a SERS sensor based on the hybrid waveguide made of metallic (Au/Al) slots and dielectric (Si3N4) strips and a method to improve the SERS-detection capacity by placing metallic nanoparticles into the sensor’s slot. The theoretical investigation of the sensor is mainly conducted by the 3D finite-difference time-domain method (3D-FDTD) which provides the broadband electromagnetic response of metallic nanostructures. The enhancement factors in the sensor’s slot are estimated based on the |E|4-approximation. The experiments are mainly the fabrication of metallic slots, which is conducted by the electron beam lithography (EBL), and the characterization of the SERS-detection capacity of the sensors. The results show that the Raman signals given out by the SERS sensors are detectable. Metallic nanoparticles, which are located in the sensor’s slot, can improve dramatically the SERS-detection capacity. By combining the SERS sensor with the extended photonic and electronic elements, a fully integrated-on-chip SERS detection system on a chip can be developed in the near future for portable and stable SERS detections

Стилі APA, Harvard, Vancouver, ISO та ін.

45

Deeb, Claire. "Optical properties of metal nanostructures as probed by photosenitive molecules." Troyes, 2010. http://www.theses.fr/2010TROY0011.

Повний текст джерела

Анотація:

Les premières études dans ce domaine ont examiné l'interaction entre les structures métalliques et les molécules photosensibles et ont prouvé la possibilité de déclencher une photo-polymérisation à l'échelle nanométrique, par le biais des plasmons de surface de ces nanoparticules. Il a été également montré que la nanophotopolymérisation constitue une technique puissante pour l'imagerie du champ proche des nanostructures, évitant ainsi la perturbation de la physique de l'échantillon en apportant une sonde à proximité. Au cours de cette thèse, nous avons été beaucoup plus quantitatifs que nos prédécesseurs dans ce domaine. En irradiant les nanoparticules de métal à leur résonance, nous avons moulé le profil dipolaire du champ électromagnétique par un polymère photo-actif, avec une résolution inédite de 5 nm. Ensuite et par une caractérisation précise des moules polymères, des valeurs précises du facteur d'exaltation et de la profondeur du champ proche de colloïdes d'argent ont été extraites. En outre, nous avons montré notre capacité à avoir une signature spectrale de la résonance plasmon d'une nanoparticule métallique unique directement en champ proche. De plus, nous présentons des cartes de résolution nanométrique de la distribution spatiale de la densité surfacique de charge créée par la discontinuité du champ électrique au niveau d’une interface métal non-résonant/diélectrique. Enfin, ce travail a prouvé que l'approche de nanophotopolymérisation constitue, d’un point de vue fondamental, une opportunité pour étudier la nanophotochimie
While past research has considered the interaction between metal nanoparticles and photo-sensitive molecules, especially the possibility of initiating nanoscale photopolymerization based on the localized surface plasmons of such particles, this PhD dissertation describes the in-depth characterization and optimization of such interactions that result in nanoscale photopolymerization. The present work demonstrates our ability to use the nanophotopolymerization process to quantitatively map with unprecedented resolution, better than 5 nm, both, the near-field of metallic nanoparticles associated with their localized surface plasmons, and the local electric fields resulting from surface charges density at metal/dielectric interfaces. We will emphasize that a precise characterization of the nanoscale molecular mold of the confined electromagnetic field of metal colloids enabled us to quantify the near-field depth and its enhancement factor. Moreover, a near-field spectrum corresponding to the response of localized surface plasmons of a single metal nanoparticle will be assessed. Additionally, we present nanoscale resolution maps of the spatial distribution of the surface charge density created by the electric field dis-continuity at a non-resonant metal/dielectric interface. Furthermore, this work will prove that the nanoscale photopolymerization approach does not only map the near-field of metal nanoparticles, yet it constitutes, from a more fundamental point of view, a unique opportunity to investigate nanophotochemistry

Стилі APA, Harvard, Vancouver, ISO та ін.

46

Tanyeli, Irem. "Effect Of Substrate Type On Structural And Optical Properties Of Metal Nanoparticles For Plasmonic Applications." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613563/index.pdf.

Повний текст джерела

Анотація:

In this work, the structural and optical properties of metal nanoparticles fabricated on various substrates have been investigated. The particles were fabricated by electron beam lithography (EBL) and dewetting of a thin metal film. The advantages and disadvantages of these two fabrication techniques are discussed by considering the properties of the nanoparticles and the applicability to large area substrates. Being a practical fabrication method, dewetting can be applied to any substrate with either small or large surfaces. For comparison between different sample types, some process parameters such as film thickness, annealing temperature and duration were fixed during the whole study. Gold (Au) and silver (Ag) were preferred for nanoparticle formation because of their superior optical properties for solar cell applications. We used silicon (Si), silicon nitride (Si3N4), silicon dioxide (SiO2) and indium tin oxide (ITO) on glass, and textured Si as the substrate for the particle formation. These substrates are commonly used in solar cell technology for different purposes. The formation of the metal nanoparticles, their size and size distribution were monitored by Scanning Electron Microscope (SEM). We performed a dimension analysis on the SEM images using a program called Gwyddion. We observed that the substrate type greatly affects particle mean size, suggesting a dependence of the dewetting process on the interface properties. Moreover, the effect of the annealing temperature was found to be a function of the substrate type. Scattering measurements have been carried out in order to observe the localized surface plasmon resonance (LSPR) conditions. The effect of the particle size and the dielectric environment was observed as a shift in the plasmon resonance peak position along the wavelength axis. As expected from the theory, the resonance peaks shift to longer wavelengths with increasing particle size and dielectric constant. In order to compare the experimental results with the theory, Mie theory was applied to calculate the plasmon resonance peaks. We obtained fairly well agreement between the experimental and theoretical results. In this study, nanoparticles were assumed to be in contact with more than one medium, namely air and the underlying substrate. Finally, we have reached a successful methodology and knowledge accumulation for the metal particle formation on variety of substrates by the dewetting technique. It is clear that this knowledge can form basis for the photovoltaic applications.

Стилі APA, Harvard, Vancouver, ISO та ін.

47

De, Silva Vashista C. "Core-Shell Based Metamaterials: Fabrication Protocol and Optical Properties." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1062904/.

Повний текст джерела

Анотація:

The objective of this study is to examine core-shell type plasmonic metamaterials aimed at the development of materials with unique electromagnetic properties. The building blocks of metamaterials under study consist of gold as a metal component, and silica and precipitated calcium carbonate (PCC) as the dielectric media. The results of this study demonstrate important applications of the core-shells including scattering suppression, airborne obscurants made of fractal gold shells, photomodification of the fractal structure providing windows of transparency, and plasmonics core-shell with a gain shell as an active device. Plasmonic resonances of the metallic shells depend on their nanostructure and geometry of the core, which can be optimized for the broadband extinction. Significant extinction from the visible to mid-infrared makes fractal shells very attractive as bandpass filters and aerosolized obscurants. In contrast to the planar fractal films, where the absorption and reflection equally contribute to the extinction, the shells' extinction is caused mainly by the absorption. This work shows that the Mie scattering resonance of a silica core with 780 nm diameter at 560 nm is suppressed by 75% and only partially substituted by the absorption in the shell so that the total transmission is noticeably increased. Effective medium theory supports our experiments and indicates that light goes mostly through the epsilon-near-zero shell with approximately wavelength independent absorption rate. Broadband extinction in fractal shells allows as well for a laser photoburning of holes in the extinction spectra and consequently windows of transparency in a controlled manner. Au fractal nanostructures grown on PCC flakes provide the highest mass normalized extinction, up to 3 m^2/g, which has been demonstrated in the broad spectral range. In the nanoplasmonic field active devices consist of a Au nanoparticle that acts as a cavity and the dye molecules attached to it via thin silica shell as the active medium. Such kind of devices is considered as a nano-laser or nano-amplifier. The fabricated nanolasers were studied for their photoluminescence kinetic properties. It is shown that the cooperative effects due to the coupling of dye molecules via Au nanoparticle plasmons result in bi-exponential emission decay characteristics in accord with theory predictions. These bi-exponential decays involve a fast superradiant decay, which is followed by a slow subradiant decay. To summarize, this work shows new attractive properties of core-shell nanoparticles. Fractal Au shells on silica cores prove to be a good scattering suppressor and a band pass filter in a broadband spectral range. They can also be used as an obscurant when PCC is used as the core material. Finally, gold nanoparticles coated with silica with dye results in bi-exponential decays.

Стилі APA, Harvard, Vancouver, ISO та ін.

48

Vindas, Yassine Karim. "Résonance plasmon et développements instrumentaux vers la conception de biopuces et biocapteurs innovants." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY091/document.

Повний текст джерела

Анотація:

Ce travail de thèse porte sur la conception d’un « laboratoire-sur-fibre » original dédié à l’analyse moléculaire à distance, sans marquage et in vivo compatible dans l’avenir avec les examens endoscopiques et dédié à l’assistance aux diagnostiques. Notre approche est basée sur l’utilisation de faisceaux de fibres microstructurés. Lorsqu’ils sont correctement conçus et recouverts d’une couche d’or, ces assemblages de fibres présentent des propriétés plasmoniques intéressantes. Dans un premier temps, le modèle numérique utilisé pour atteindre une meilleure compréhension des phénomènes physiques impliqués dans l’optimisation de la sensibilité des capteurs est expliqué. Les simulations, basées sur l’optique géométrique, ont été utilisées pour optimiser la géométrie des pointes et l’épaisseur de la couche d’or dans le but d’améliorer les performances analytiques et permettre ainsi des détections d’interactions biochimiques. Le processus de fabrication des capteurs est ensuite expliqué depuis leur structuration par gravure chimique effectuée à l’ISM (Bordeaux) jusqu’à leur métallisation réalisée au CEA Grenoble. Une comparaison entre les comportements théoriques et expérimentaux et alors menée pour comprendre l’influence de l’hétérogénéité du dépôt d’or et des surfaces gravées sur la sensibilité optique. Ces propriétés optiques sont ensuite exploitées jusqu’à la preuve de concept d’analyses biochimiques déportées. Cette étape a été réalisée en deux temps : d’abord la sensibilité à l’indice local a été démontrée en détectant l’adsorption d’une couche organique auto-assemblée et ensuite un suivi de l’interaction spécifique entre deux brins d’ADN complémentaires a été effectué. Le manuscrit s’achève par une analyse des aspects plus complexes liés à la nature peu multimodale des fibres présentes dans le faisceau. La théorie des guides d’ondes est alors utilisée pour expliquer l’influence du caractère modal de la propagation de la lumière sur les réponses des fibres optiques
This Ph.D. thesis focuses on the design of an original “lab-on-fiber” tool for remote, label-free in vivo molecular analysis that could be dedicated in the future to endoscopic diagnosis. Our approach is based on functionalized microstructured optical fiber bundles. When appropriately designed and covered by a gold layer, those fibers exhibit interesting plasmonic properties. First, the numerical model used to reach a better understanding of the physical phenomena involved in the optimization of the sensor’s sensitivity is explained. The simulations based on ray optics were then used to optimize the fiber tip geometry and gold coating thickness to enhance the analytical performances and ultimately allow biochemical detections. The fabrication process of the sensor is then explained going from the chemical etching done by the ISM team (Bordeaux) to the metallization of the tips performed at the CEA Grenoble. A comparison between theoretical and experimental behaviors is then conducted to assess the influence of the heterogeneity of both the gold deposit and the etched surfaces on the optical sensitivity. Afterwards, we take advantage of those optical properties to perform remote biochemical analysis. This was achieved in two steps: we first proved that our sensor was sensitive to local optical index variations by detecting the adsorption of a thin self-assembled organic layer and ultimately a specific interaction between two complementary DNA strands was monitored. The last part of this work tackles the more difficult aspects of the few-modes fibers composing the bundle. Waveguide theory is then used to explain the influence of the modal characteristics of light propagation on the optical fibers responses

Стилі APA, Harvard, Vancouver, ISO та ін.

49

Ching, Suet Ying. "Plasmonic properties of silver-based alloy thin films." HKBU Institutional Repository, 2015. https://repository.hkbu.edu.hk/etd_oa/194.

Повний текст джерела

Анотація:

The plasmonic properties of silver-based alloy thin films were studied. Silver-ytterbium (Ag-Yb) and silver-magnesium (Ag-Mg) prepared by thermal co-evaporation were investigated extensively for various thin film properties. The optical properties were intensively analyzed and discussed because the dielectric response of a material is particularly significant in terms of its plasmonic properties. The study of silver-based alloy thin films has been mostly about Ag alloying with other transition metals, but the results of Ag-Yb and Ag-Mg in this work showed that the intensity of plasma resonance is tunable, in which the idea may also apply to other silver-rich binary alloy thin films regardless of the kind of second metal components. In our research, the Ag plasma resonance was weakened with respect to the concentration of Yb and Mg in the alloy thin films. The change in the optical characteristics around Ag plasma resonance frequency was attributed to an increase in “resonance damping. This is confirmed from modeling using classical free-electron theory. The increase in the damping was experimentally corroborated by the concentration dependence of electrical conductivity and estimated average crystallite size of Ag-Yb and Ag-Mg thin films. The reduction in electrical conductivity was not only caused by introducing less conductive Yb or Mg but also through disturbing the Ag lattice structure to promote additional electron scattering at grain boundaries. The Ag-Yb and Ag-Mg alloys carried intermediate properties between their pure components despite the presence of Yb or Mg oxides. Besides optical and electrical properties, changes in the electronic work function were also assessed since it is also important in applications. Plasmonic nanostructures and transparent organic light-emitting diodes (OLEDs) were fabricated to demonstrate their potential applications. Two-dimensional disc-arrays nanostructures composed of pure Ag and Ag-Yb were implemented to evaluate the plasmonic properties. The damping loss in Ag-Yb caused weakened coupling of incident photons and surface plasmons when compared to pure Ag without altering the coupling wavelengths, suggesting potential plasmonic materials for tuning the coupling strength of surface plasmons by controlling the concentration of Yb which may also apply to Ag-Mg. Ultrathin Ag-Yb and Ag-Mg films were used as cathodes in transparent OLEDs for demonstration, which was beneficial by virtue of overall device transmittance though sacrificing electrical conduction leading to poor light emission unless inserting additional ultrathin lithium fluoride to modify the ultrathin cathodes.

Стилі APA, Harvard, Vancouver, ISO та ін.

50

Vernoux, Christian. "Fabrication and optical characterization of long-range plasmonic waveguide interconnects for Tb/s datacom links." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCK001/document.

Повний текст джерела

Анотація:

Depuis les années 1980, les chercheurs essayent de concevoir des ordinateurs dits « optiques », au sein desquels les signaux électriques seraient remplacés par des signaux photoniques. Pour cela, il est nécessaire de s’intéresser aux problèmes d’interconnexions entre les composants. Cette thèse porte sur la problématique de l’interconnexion optique entre composants électroniques. Afin de proposer une solution à cette problématique, nous étudierons deux types de structures plasmoniques, une première structure d’un seul bloc solide où l’onde d’information est réfléchie sur un prisme d’air, cette structure est composée d’un guide d’onde métallique recouverte d’une couche de photoresist et elle est nommée « guide plasmonique à ultra longue distance » (ULR-SPP). La seconde structure est basée sur une interconnexion flexible où l’information circule le longue d’un guide souple, ce type d’onde est qualifié de « PlasArc ». Au travers d’un chapitre de simulation numérique, nous déterminerons les caractéristiques dimensionnelles afin de minimiser les pertes d’énergies par propagations de nos guides d’ondes dans chacune des structures. Toutes nos simulations sont effectuées dans la gamme d’ondes des signaux télécoms. Puis, nous présentons la fabrication de nos deux types de guides d'ondes ainsi que leurs spécificités de réalisation à savoir une gravure profonde sèche de 60 µm pour les structures ULRSPP et le retrait d’un substrat solide pour les guides « PlasArc ». La caractérisation de nos structures seront réalisées par des méthodes distinctes (réduction successive de la longueur des échantillons, mesures de la perte par propagation le long du guide, taille du mode obtenu en bout de guide, …) sur des tailles d’échantillons pouvant aller de 5 mm à plusieurs centimètres de longueurs. Une étude de la perte selon le rayon de courbure est établie sur les guides d’ondes plasmoniques de type « PlasArc »
Since the 1980s, researchers have been trying to design so-called "optical" computers, in which electrical signals would be replaced by photonic signals. For this, it is necessary to look at interconnection problems between components. This thesis deals with the problem of optical interconnection between electronic components. In order to propose a solution to this problem, we will study two types of plasmonic structures, a first structure of a single solid block where the information wave is reflected on an air prism, this structure is composed of a guide of metal wave covered with a layer of photoresist and it is named "ultra-long-distance plasmonic guide" (ULR-SPP). The second structure is based on a flexible interconnection where the information flows along a flexible guide, this type of wave is called "PlasArc". Through a numerical simulation chapter, we will determine the dimensional characteristics in order to minimize the energy losses by propagation of our waveguides in each of the structures. All our simulations are performed in the waveband of telecom signals. Then, we present the fabrication of two types of plasmonic waveguides as well as their specificities of realization namely a deep etching of 60 μm for ULRSPP structures and the removal of a solid substrate for waveguide named "PlasArc". The characterization of structures will be realized by distinct methods (cut-back, measurements of the loss by propagation along the guide, size of the mode obtained at the end of the guide, ...) on sizes of samples that can go from 5 mm to several centimeters in length. A study of the loss according to the radius of curvature is established on plasmonic waveguides of "PlasArc" type

Стилі APA, Harvard, Vancouver, ISO та ін.

Дисертації з теми "Optical Plasmons"

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями