Dissertations / Theses on the topic 'Plasmonic modulators'
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Abadía, Calvo Nicolás Mario. "Ultra-compact plasmonic modulator for optical inteconnects." Thesis, Paris 11, 2014. http://www.theses.fr/2014PA112353/document.
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Ce travail vise à concevoir un modulateur optique assisté par plamsons, compatible CMOS et à faible consommation électrique. L’électro-absorption, basée sur l’effet Franz-Keldysh dans le germanium, a été choisie comme principe de modulation pour réduire la taille du dispositif et la consommation d'énergie électrique associée. L’effet Franz-Keldysh se traduit par un changement du coefficient d'absorption du matériau près du bord de bande sous l'application d'un champ électrique statique, d'où la production d'une modulation directe de l'intensité lumineuse. L'utilisation de plasmons permet en principe d’augmenter l'effet électro-optique en raison du fort confinement du mode optique. Un outil de simulation électro-optique intégré a été développé pour concevoir et optimiser le modulateur. Le modulateur plasmonique proposé a un taux d'extinction de 3.3 dB avec des pertes d'insertion de 11.2 dB et une consommation électrique de seulement 20 fJ/bit, soit la plus faible consommation électrique décrite pour les modulateurs photoniques sur silicium. Le couplage du modulateur à un guide silicium standard en entrée et en sortie a également été optimisé par l’introduction d'un adaptateur de mode Si-Ge optimisé, réduisant les pertes de couplage à seulement 1 dB par coupleur. Par ailleurs, un travail expérimental a été effectué pour tenter de déplacer l'effet Franz-Keldysh, maximum à 1650 nm, à de plus faibles longueurs d'onde proches de 1.55 μm pour des applications aux télécommunications optiquesThis work aims to design a CMOS compatible, low-electrical power consumption modulator assisted by plasmons. For compactness and reduction of the electrical power consumption, electro-absorption based on the Franz-Keldysh effect in Germanium was chosen for modulation. It consists in the change of the absorption coefficient of the material near the band edge under the application of a static electric field, hence producing a direct modulation of the light intensity. The use of plasmons allows enhancing the electro-optical effect due to the high field confinement. An integrated electro-optical simulation tool was developed to design and optimize the modulator. The designed plasmonic modulator has an extinction ratio of 3.3 dB with insertion losses of 13.2 dB and electrical power consumption as low as 20 fJ/bit, i.e. the lowest electrical power consumption reported for silicon photonic modulators. In- and out-coupling to a standard silicon waveguide was also engineered by the means of an optimized Si-Ge taper, reducing the coupling losses to only 1 dB per coupler. Besides, an experimental work was carried out to try to shift the Franz-Keldysh effect, which is maximum at 1650 nm, to lower wavelength close to 1.55 μm for telecommunication applications
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Demir, Veysi. "Nanocomposites for High-Speed Optical Modulators and Plasmonic Thermal Mid-Infrared Emitters." Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/581130.
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Demand for high-speed optical modulators and narrow-bandwidth infrared thermal emitters for numerous applications continues to rise and new optical devices are needed to deal with massive data flows, processing powers, and fabrication costs. Conventional techniques are usually hindered by material limitations or electronic interconnects and advances in organic nanocomposite materials and their integration into photonic integrated circuits (PICs) have been acknowledged as a promising alternative to single crystal techniques. The work presented in this thesis uses plasmonic and magneto-optic effects towards the development of novel optical devices for harnessing light and generating high bandwidth signals (> 40GHz) at room and cryogenic temperatures (4.2°K). Several publications have resulted from these efforts and are listed at the end of the abstract. In our first published research we developed a narrow-bandwidth mid-infrared thermal emitter using an Ag/dielectric/Ag thin film structure arranged in hexagonal planar lattice structures. PECVD produced nanoamorphous carbon (NAC) is used as a dielectric layer. Spectrally tunable (>2 μm) and narrow bandwidth (<0.5 μm) emission peaks in the range of 4-7μm were demonstrated by decreasing the resistivity of NAC from 10¹² and 10⁹ Ω.cm with an MoSi₂ dopant and increasing the emitter lattice constant from 4 to 7 μm. This technique offers excellent flexibility for developing cost-effective mid-IR sources as compared to costly fiber and quantum cascade lasers (QCLs). Next, the effect of temperature on the Verdet constant for cobalt-ferrite polymer nanocomposites was measured for a series of temperatures ranging from 40 to 200°K with a Faraday rotation polarimeter. No visual change was observed in the films during thermal cycling, and ~4x improvement was achieved at 40°K. The results are promising and further analysis is merited at 4.2°K to assess the performance of this material for cryogenic magneto-optic modulators for supercomputers. Finally, the dielectric constant and loss tangent of MAPTMS sol-gel films were measured over a wide range of microwave frequencies. The test structures were prepared by spin-coating sol-gel films onto metallized glass substrates. The dielectric properties of the sol-gel were probed with several different sets of coplanar waveguides (CPWs) electroplated onto sol-gel films. The dielectric constant and loss-tangent of these films were determined to be ~3.1 and 3 x 10⁻³ at 35GHz. These results are very promising indicating that sol-gels are viable cladding materials for high-speed electro-optic polymer modulators (>40GHz).
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Ummethala, Sandeep [Verfasser], and C. [Akademischer Betreuer] Koos. "Plasmonic-Organic and Silicon-Organic Hybrid Modulators for High-Speed Signal Processing / Sandeep Ummethala ; Betreuer: C. Koos." Karlsruhe : KIT-Bibliothek, 2021. http://d-nb.info/1239180586/34.
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Sharma, Sumeet. "All Plasmonic Noble Metal Modulator." Thesis, California State University, Long Beach, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10978327.
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At present modulators in communications industry utilize non-linear materials like indium tin oxide (ITO) and DLD-164 as a dielectric, which makes the fabrication process cumbersome and expensive. This thesis discusses the possibility of using only gold and air as conductor and dielectric to characterize a signal modulating device. Both electro-absorption modulation (EAM) and phase change driven modulation is possible with the design. For the change in phase a length of 2.992 µm for the modulating arm of a Mach-Zehnder modulator (MZM) was achieved for operation at 525 nm. High absorptions of electromagnetic (EM) waves was seen at the 480 nm mark allowing a length of just 4.95 µm for EAM. The results suggest that an all plasmonic noble metal modulator utilizing air as a dielectric is possible for operation in the visible 400 nm to 700 nm range. The concept is supported by proof-of-principle based simulations.
This thesis proposes a novel idea of an all plasmonic modulator driven by changes in free carrier concentration in gold and surface plasmon polariton (SPP) excitations under an applied potential. The prototype model is simulated using a commercial finite difference time domain solver. The simulation enviro nment allows Maxwell’s equations to be solved in the time domain to investigate light propagation and absorption characteristics under an externally applied electric potential. The free carrier concentration dependent permittivity of gold is exploited to investigate possible applications in nano-photonics and optical communications.
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Ansell, Daniel. "Graphene for enhanced metal plasmonics." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/graphene-for-enhanced-metal-plasmonics(7bb0ffb1-f46f-498e-bb88-9626021f6f58).html.
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The experimental work undertook in this thesis looks to integrate technologies developed by the graphene and plasmonics communities, respectively, for the purpose of producing devices of enhanced qualities to those of similar utility that have previously been produced. Furthermore, where possible, we look to offer disruptive innovation, by utilising coupled properties that may offer unique possibilities for applications. A hybrid graphene-plasmonic waveguide modulator is fabricated and shown to operate successfully at a standard telecommunications frequency. Different plasmonic-waveguide designs — the basis for the modulator — were produced to probe the coupling between graphene and the surface plasmon-polariton modes. A mode excitable at the edge of the waveguide was found to offer the best modulation, with a modulation depth of over 0.03 dB μm^−1, induced by a moderate gating voltage of about 10 V. Topologically-protected darkness (zero reflection) was produced by particular engineering of a plasmonic metamaterial. This allowed generation of a singularity in the ellipsometric phase (a particular parameter of light), allowing for measurements of mass sensitivity of ∼10 fg mm^−2, with the possibility of improving this to ∼100 ag mm^−2. Graphene was employed in a novel metrology tool to measure the sensitivity of this device. With respect to fundamental losses in plasmonics, one could find either a new plasmonic material or look to improve an existing one. Work was undertook with respect to this latter option by attempting to preserve the otherwise excellent plasmonic properties of copper and silver through a protective barrier of graphene. This was achieved and illustrated through ellipsometric measurements taken over various timescales. Fabrication of a dielectric loaded waveguide on graphene-protected copper was then carried out, with operation of the waveguide proving successful, possibly opening the field of active graphene-protected metal plasmonics.
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Ning, Ding. "Analytical and Numerical Models of Multilayered Photonic Devices." University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1207712683.
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Thomas, Philip. "Narrow plasmon resonances in hybrid systems." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/narrow-plasmon-resonances-in-hybrid-systems(a2e3a6e8-1055-4e7e-8b35-a597163aacc8).html.
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Surface plasmons are collective oscillations of free electrons excited at a metal-dielectric interface by incident light. They possess a broad set of interesting properties including a high degree of tunability, the generation of strong field enhancements close to the metal's surface and high sensitivity to their adjacent dielectric environment. It is possible to enhance the sensitivity of plasmonic systems by using narrow plasmon resonances. In this thesis two approaches to narrowing surface plasmon resonances have been studied: diffraction coupling of localised surface plasmon resonances in gold nanoarrays and the use of graphene-protected copper thin films. Applications of these approaches in hybrid systems have been considered for modulation, waveguiding, biosensing and field enhancements. Arrays of gold nanostripes fabricated on a gold sublayer have been used to create extremely narrow plasmon resonances using diffraction coupling of localised plasmon resonances with quality factors up to a value of $Q \sim 300$, among the highest reported in the literature. The nanostructures were designed to give the narrowest resonance at the telecommunication wavelength of 1.5 µm, allowing for this array geometry to be used in hybrid systems for proof-of-concept optoelectronic devices. The gold nanostripe array was used in a hybrid nanomechanical electro-optical modulator along with hexagonal boron nitride (hBN) and graphene. The modulator was fabricated with an air gap between the nanoarray and the hexagonal boron nitride/graphene. Applying a gate voltage across the device moves the hBN towards the nanoarray, resulting in broadband modulation effects from the ultraviolet through to the mid-infrared dependant on the motion of the hBN instead of graphene gating. The deposition of a 400 nm hafnium(IV) oxide film on top of the gold nanoarray created a structure capable of guiding modes at 1.5 µm. The hybrid air-dielectric-stripe waveguide is capable of guiding modes over a distance of 250 µm. Copper thin films have stronger plasmon resonances and higher phase sensitivity than gold thin films. Transferring a graphene sheet on the copper prevents oxidation of the copper. A feasibility study of this hybrid system has shown that phase-sensitive graphene-protected copper biosensing can detect HT-2 mycotoxin with over four orders of magnitude greater sensitivity than commercially-available gold-based surface plasmon resonance biosensing systems. In summary, two methods of attaining narrow plasmon resonances have been demonstrated and their promise in modulation, waveguiding and biosensing have been demonstrated.
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Hassan, Sa'ad. "Microfabrication of Plasmonic Device: PPBG BIosensor in Cytop, Reflection Itensity Modulator and Atomically Flat Nanohole Array." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32324.
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This thesis details the fabrication of three different plasmon-polariton based devices: a plasmon-polariton Bragg grating (PPBG) biosensor, an intensity modulator incorporating grating couplers, and optically separated electrical contact, and finally an array of nanoholes in an ultrasmooth Au film. The biosensor involves a 35 nm Au stripe, lithographically stepped in width to produce a Bragg reflector. The waveguide is embedded in symmetric, Cytop claddings 8 µm thick. Channels are etched into the top cladding, exposing the waveguides and allowing for the integration of fluidics. The modulator involves a 20 nm Au pad, overlaid with 80 nm Au diffraction gratings, supported by an ultrathin (~3 nm) SiO2 insulator, on a p-doped Silicon wafer backed by an Al Ohmic contact. Electrical contact pads are separated from the waveguide by a thick dielectric (700 nm PMMA), and 2.5 µm vias in-filled with Au allow for electrical connection between the contact pads and waveguides. The nanohole array is machined by focused ion beam into an ultrasmooth Au film revealed by template stripping. The Au film is stacked on a thick film of Cytop between ~5 µm thick.
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Mota, F. "The discovery of small molecule modulators of soluble guanylate cyclase aided by surface plasmon resonance." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1434127/.
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Soluble guanylate cyclase is a multidimeric enzyme that regulates cardiovascular homeostasis and is the receptor for nitric oxide in the brain. The enzyme is the known target for a new agonist drug used for the treatment of pulmonary hypertension. Whilst drug discovery has been successful for the finding of small molecules that activate the enzyme, the currently available inhibitors lack selectivity as they act through oxidation of a heme prosthetic group in the enzyme, which is conserved amongst other hemeproteins. Nonetheless, it has been suggested that inhibition of soluble guanylate cyclase by small molecules could be useful in the treatment of neurological conditions such as Parkinson’s Disease. In this thesis, new activators of soluble guanylate cyclase have been identified by virtual screening, and a new class of inhibitors has been designed and synthesised. The synthetic routes developed are efficient and take advantage of microwave-assisted organic synthesis. The drug-target interaction was characterised using a biophysical technique based on surface plasmon resonance, which allows the detection of label-free binding between small molecules and biological macromolecules. The biophysical assay has been developed using different constructs of soluble guanylate cyclase and validated through binding of the natural ligands ATP and GTP. The instrument and assay design were validated using the well-defined interaction between natriuretic peptides and the extracellular domain of natriuretic peptide type-C. Additional biochemical characterisation of the ligands allowed discrimination between activators and inhibitors. This combination of biophysical and biochemical techniques allowed the identification of the catalytic domain of soluble guanylate cyclase as the target for binding of the new class of synthesised inhibitors and has given insight into the functional groups necessary for activity and binding to the enzyme.
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Hon, Kam Yan. "Surface plasmon resonance-assisted coupling to whispering-gallery modes in micropillar resonators and silicon microdisk-based depletion-type modulators using integrated schottky diodes /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?ECED%202007%20HON.
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Emboras, Alexandros. "Intégration en technologie CMOS d'un modulateur plasmonique à effet de champ CMOS Integration of a field effect plasmonic modulator." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00848107.
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Dans la réalisation de circuits intégrés hybrides électroniques - photoniques pour les réseaux télécom, les modulateurs intégrés plasmoniques pourront jouer un role essentiel de codage de l'information en signaux optiques. Cette thése montre la réalisation d'une approche modulateur plasmonique a effet de champ, intégrée en silicium en utilisant les technologies CMOS standards. Ce modulateur MOS plasmonique présente diverses propriétés intéressantes, a savoir un confinement optique fort, permettant une augmentation de l'interaction lumiére matiére. Ces modulateurs plasmoniques permettent aussi de réduire l'inadéquation entre la taille des dispositifs en photonique Si et celle de l' électronique, ce qui permet d'envisager une convergence de leur fabrication en technologie VLSI sur une meme puce. Le modulateur étudié dans ce mémoire repose sur l'accumulation de porteurs dans un condensateur MOS a grille cuivre integer dans un guide d'onde en silicium, nécessitant aux technologies front end et back end Cu d etre combinés de quelques nanométres l'une de l'autre. Nous présentons aussi de nouveaux designs pour injecter de la lumiére a partir de guide d'onde SOI dans un guide a nanostructure plasmonique et les mesures d'une modulation électro-optique dans les structures MOS plasmoniques
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Plumereau, Christine. "Utilisation de plasmons de surface à faibles pertes pour la modulation de la lumière par effet électro-optique." Saint-Etienne, 1990. http://www.theses.fr/1990STET4007.
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L'étude proposée s'insère dans le cadre de travaux concernant la réalisation de guides plans et l'analyse du fonctionnement de dispositifs utilisant des ondes optiques de surface de type plasmons. L'excitation de plasmons de surface se matérialisant par des pics de résonance étroits dans les courbes de réflexion totale atténuée, il est possible d'utiliser de telles ondes dans des dispositifs de type modulateur électro-optique. Une étude des guides plans comportant une interface métallique permet de mettre en évidence le comportement de modes guides particuliers faisant intervenir une oscillation collective des électrons du métal (plasmons). L'équation de dispersion d'une structure guidante est alors traitée de façon généralisée pour montrer les couplages qui peuvent intervenir entre deux plasmons identiques dans des structures de type métal /diélectrique / métal : ces résultats permettent de caractériser les plasmons de surface à faibles pertes. La modélisation des courbes de réflectivité permet ensuite de voir quelles sont les modifications apportées aux caractéristiques des plasmons quand on utilise un coupleur à prisme. L'aspect modélisation de dispositifs de modulation du faisceau réfléchi par effet électro-optique est abordé : ces modèles permettent de prévoir les performances de tels modulateurs et montrent que l'utilisation des plasmons de surface à faibles pertes peut conduire à des résultats comparables à ceux obtenus avec des modes guides dans des diélectriques. Enfin, on montre qu'il est possible grâce au dispositif de mesure mis en oeuvre de comparer facilement les résultats théoriques provenant d'une modélisation et les courbes expérimentales résultant de mesure du coefficient de réflexion
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Badhwar, Shruti. "Laterally confined THz sources and graphene based THz optics." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/246259.
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The region between the infrared and microwave region in the electromagnetic spectrum, the Terahertz (THz) gap, provides an exciting opportunity for future wireless communications as this band has been under utilised. This doctoral work takes a two-pronged approach into closing the THz gap with low-dimensional materials. The first attempt addresses the need for a compact THz source that can operate at room temperature. The second approach addresses the need to build optical elements such as filters and modulators in the THz spectrum. Terahertz quantum cascade lasers (THz QCLs) are one of the most compact, powerful sources of coherent radiation that bridge the terahertz gap. However, their cryogenic requirements for operation limit the scope of the applications. This is because of the electron-electron scattering and heating of the 2-dimensional free electron gas which leads to significant optical phonon scattering of the hot electrons. Theoretical studies in laterally confined QCL structures have predicted enhanced lifetime of the upper state through suppression of the non-radiative intersubband relaxation of carriers, which leads to lower threshold, and higher temperature performance. Lithographically defined vertical nanopillar arrays with electrostatic radius less than tens of nm offer a possible route to achieve lateral confinement, which can be integrated into QCL structures. A typical gain medium in a QCL consists of at least 100 repeat periods, with a thickness of 6-14 micron. For practical implementation of the top-down approach, restrictions are imposed by aspect ratios that can be achieved in present dry-etching systems. Typically, for sub-200 nm radius pillars, the thickness ranges from 1-3.5 micron. It is therefore necessary to work with THz QCLs based on 3-4 quantum well active regions, so as to maximise the number of repeat periods (hence gain) within an ultra-thin active region. After an introductory chapter, Chapter 2 presents a theoretical treatise on the realistic electrostatic potential in a lithographically defined nanopillar by scaling from a single quantum well (resonant tunnelling diode) to a THz QCL. Chapter 2 also discusses, the effect of lateral confinement on the intersubband states and the plasmonic mode in a THz QCL. One of the key experimental challenges in scaling down from QCLs to quantum-dot cascade lasers is the electrical injection into the nanopillars. This involves insulation and planarisation of the high aspect-ratio nanopillar arrays. Furthermore, the choice of the planarising layer is critical since it determines the loss of any optical mode. This experimental challenge is solved in Chapter 3. Chapter 4 presents the electro-optic performance of low-repeat period QCLs with an active region thickness that is less than 3.5 micron. Another topic of recent interest in the THz optics community is plasmonics in graphene. This is because the bound electromagnetic modes (plasmons) are tightly confined to the surface and can also be tuned with carrier concentration. Plasmonic resonance at terahertz frequencies can be achieved by gating graphene grown via chemical vapour deposition (CVD) to a high carrier concentration. THz time domain spectroscopy of such gated monolayer graphene shows resonance features around 1.6 THz superimposed on the Drude-like frequency response of graphene which may be related to the inherent poly-crystallinity of CVD graphene. Chapter 5 discusses these results, as an understanding of these features is necessary for the development of future THz optical elements based on CVD graphene. Chapter 5 finally describes how the gate tunability of THz transmission through graphene can be exploited to indirectly modulate a THz QCL. Chapter 6 presents ideas from this doctoral work, which can be developed in future to address the issues of enhanced temperature performance of THz QCLs and to realise realistic THz devices based on graphene.
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Haron, Zainal Alam Bin. "A study of the surface plasmon resonance effect in three-phase and four-phase systems and its viability in optical modulator or switching applications." Thesis, University of Newcastle Upon Tyne, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386715.
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Trouillet, Alain. "Réalisation de guides optiques plans en polymères non linéaires : application à la modulation électrooptique de plasmons de surface à faibles pertes." Saint-Etienne, 1994. http://www.theses.fr/1994STET4003.
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Ce mémoire présente l'étude des propriétés optiques non linéaires de matériaux polymères et met en évidence l'intérêt d'un plasmon de surface à faibles pertes pour réaliser un modulateur électrooptique en optique intégrée. Après une présentation générale des propriétés optiques non linéaires dans les polymères, nous décrivons la caractérisation de composés nouveaux obtenus par copolymérisation du styrène avec des comonomères non linéaires dérivés du CMS (chlorométhylstyrène) ou bien du HEMA (hydroxyéthylméthacrylate). Des coefficients non linéaires d33 compris entre 1 et 13 pm/v ont été déterminés en réalisant des expériences de doublement de fréquence, à 1064 nm, en transmission au travers de guides plans déposés sur verre et orientés par corona-poling. Nous avons étudié l'évolution temporelle de ces propriétés. Dans une seconde partie, nous présentons l'étude de modulateurs électrooptiques dont le matériau actif est un polymère et dans lesquels un film métallique sert à la fois d'électrode et de support pour l'onde optique qui est un plasmon de surface. Nous avons utilisé ce mode particulier, dont l'origine est associée à l'excitation d'oscillations de plasma du milieu métallique, pour mesurer le coefficient électrooptique r33 a 632. 8 nm. Un modulateur dans lequel une électrode mince d'argent est encadrée par deux polymères d'indices voisins est susceptible de fonctionner avec des tensions de commande de quelques volts en excitant un plasmon de surface à faibles pertes. Des simulations numériques et une étude expérimentale sont présentées
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Mebarki, Lamia. "Recherche ou développement, et caractérisation fonctionnelle et structurale d'effecteurs peptidiques de deux récepteurs membranaires à incidences physiopathologiques." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0217.
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Les récepteurs à la vasopressine V1bR et à la sérotonine 5HT3R jouent des rôles physiologiques importants dans la détection des signaux extracellulaires, les mécanismes de transmission nerveuse et diverses pathologies dont le cancer, le diabète et des maladies des SNC et SNP. Mes études avaient pour but de générer ou trouver des modulateurs peptidiques de ces deux récepteurs. Pour le V1bR, j’ai développé plusieurs anticorps de type VHH et les ai caractérisés aux plans biochimique et fonctionnel. L’un de ces VHHs agit comme un agoniste allostérique complet et spécifique du V1bR humain (hV1bR). In vitro ce VHH est capable d’activer les voies de signalisation de l’inositol phosphate et des MAP kinases et d’induire l'internalisation du hV1bR. Dans des îlots pancréatiques surexprimant le hV1bR, il induit une augmentation du Ca2+ intracellulaire et une sécrétion d'insuline. Pour le 5HT3R, j’ai criblé par SPR 31 venins de serpents sur des récepteurs recombinants immobilisés et mis en évidence une interaction à partir d’un de ces venins. Suite à purification par chromatographie liquide et identification par spectrométrie de masse, j’ai identifié une toxine préalablement caractérisée comme une enzyme à activité Ca2+-dépendante. Cette toxine interagit avec les 5HT3R A et AB indépendamment du Ca2+ et avec des valeurs de Kd ≤ 10 nM. L’analyse fonctionnelle par électrophysiologie suggère qu’elle agit comme un PAM de l’activité canal du 5HT3R. Des images de ME en coloration négative montrent la toxine fixée sur le domaine extracellulaire du 5HT3R, à distance du site pour la 5HT. Le VHH et la toxine pourraient être utilisés comme outils pharmacologiques et/ou agents thérapeutiquesThe vasopressin V1bR and serotonin 5HT3R receptors play important physiological roles in the detection of extracellular signals, in the mechanisms for neuronal transmission, and in various pathologies including cancer, diabetes, and CNS and PNS diseases. My studies were aimed at generating or finding peptidic modulators of these two receptors. For the V1bR, I developed several antibodies of the VHH type and characterized them biochemically and functionally. One of these VHHs acts as a complete allosteric agonist specific for the human V1bR (hV1bR). In vitro this VHH is able to activate the signaling pathways of inositol phosphate and MAP kinases and to induce the internalization of hV1bR. In pancreatic islets overexpressing hV1bR, it induces an increase in intracellular Ca2+ and a secretion of insulin. For the 5HT3R, using SPR I screened 31 snake venoms on immobilized recombinant receptors and for one of these venoms, evidenced an interaction. Following purification by liquid chromatography and identification by mass spectrometry, I identified a toxin previously characterized as an enzyme with Ca2+-dependent activity. This toxin interacts with the 5HT3R A and AB independently of Ca2+ and with Kd values ≤ 10 nM. Functional analysis by electrophysiology suggests that it acts as a PAM of the 5HT3R channel activity. Images recorded by negative staining EM show that the toxin binds to the 5HT3R extracellular domain, at a distance from the 5HT binding site. Both this VHH and this toxin could be used as pharmacological tools and / or therapeutic agents
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Stolz, Arnaud. "Conception, fabrication et caractérisation d'un modulateur optique à commande plasmonique sur nitrure de gallium à une longueur d'onde de 1,55 micron." Phd thesis, Université de Valenciennes et du Hainaut-Cambresis, 2011. http://tel.archives-ouvertes.fr/tel-00677475.
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Les futurs modulateurs optiques doivent satisfaire à des exigences auxquelles les modulateurs électro-optiques actuels ne peuvent plus répondre (tension de commande et dimensionnement faible, fonctionnement dans la gamme 0-40GHz à faibles pertes). Il devient alors nécessaire d'envisager de nouveaux moyens de réaliser une modulation rapide à faible consommation. Ce travail s'inscrit au sein d'un projet amont de la DGA, afin d'évaluer le gain potentiel de la plasmonique sur semiconducteurs pour la modulation optique. Nous avons d'abord sélectionné des couches de GaN sur saphir avec d'excellentes propriétés optiques et des pertes de propagation de l'ordre de 0,6dB/cm. Ensuite, nous avons montré la génération d'une résonance plasmonique à l'interface Au/GaN. Un travail d'optimisation a été réalisé en vue de rendre sa modulation efficace par variation de l'indice du GaN. Plusieurs dispositifs de démonstration ont été fabriqués en salle blanche puis caractérisés. Si les résultats optiques obtenus ont montré un effet de variation d'indice nouveau jusqu'à Δn=10-2 pour plusieurs dizaines de volt, les pertes RF de propagation se sont révélées élevées, proches de 16dB/cm à 20GHz. En parallèle, une structure à effet d'électro-absorption utilisant un multipuits quantique sur InP a été conçue et caractérisée par couplage par prisme et a montré des variations d'indice de l'ordre de 2×10-3 à 2,5V. Ces travaux de thèse, précurseurs dans ce domaine au sein du laboratoire, vont permettre d'orienter les recherches futures vers de nouveaux matériaux pour l'optoélectronique, mais aussi de mettre en exergue les points durs de la plasmonique pour la modulation optique sur semiconducteurs.
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Chang, Cheng Wei, and 張正偉. "Synthesis and applications of visible plasmonic Silver: Far surface plasmon polariton (SPP) propagation, excellent photodegradation, and SPP amplitude modulations." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/64973h.
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博士國立清華大學
材料科學工程學系
105
Since surface plasmon polarition (SPP) waves propagate in the definite dielectric/metal region, the propagation loss is an important issue and related to the optical responses like on-resonance states or coupling frequencies. In visible region, plasmonic material Ag has attracted great attentions because of low absorption loss. However, the losses in Ag are not only attributed to the interband or intraband transitions but also to the surface defects and the impurities. We herein develop a fabrication method called HNO3-assisted polyol reduction method that possesses mass production single-crystalline Ag microplates with the largest lateral size up to 50 μm. The growth mechanism and the improved SPP propagation length are investigated, showing that the concentrations of ethylene glycol (EG), HNO3 dominate the growth of Ag microplates and the SPP propagation length is 2 folded longer than the typical E-gun deposited Ag thin film. Such the ultralarge Ag microplates can serve as the low defected, versatile used, buffer layer free plasmonic platform Furthermore, using HNO3-assisted polyol reduction method can control the lateral size of Ag microplates. The use of relatively small size Ag microplates with 3-5 μm is carried out for sinking the photogenerated electrons in the ZnO/Ag heterostrcuture. The growth of ZnO nanowires on Ag microplates shows that the directly contact and the charge transfer effect are confirmed by TEM and XPS observation. The ZnO/Ag contacts can effectively enhance the photocatalytic activity in photoinduced degradation processes, showing that the kinetic constant for our ZnO/Ag heterostructure possesses 1.35 folds than the pure ZnO nanowires. The figure of merit (FOM) value is used for fairly comparing the ability of photodegradation among other ZnO/Ag heterostructure, revealing that our ZnO/Ag heterostructure has a better performance than others (1.02 × 10-2). In the final part, we use metallic Ag and plasmonic Fishbone (FB) structures to develop two kinds of SPP amplitude modulation (SPPAM). One is the use of angular frequency difference to serve as a modulation signal and beats on 1.66 MHz, showing that beat frequency SPPAM works beyond SPP subwavelength region and can be readout by the oscilloscope construction. The other is the use of changing polarization states frequencies and polarization states that can act as the modulation signals in the ranges of 1-10k Hz, showing that the intensity difference between the left/right-sided FB structures with the modulation signals. Taking the advantages of reducing the power consumption and the channel length, we believe that the compact SPPAMs can be used for miniaturizing the modulators and upgrade the 8/16 coding bits to multi-bits.
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Chen, Tai-Yu, and 陳泰佑. "Development of Soft X-ray Frequency Modulator with Surface Plasmonic Device." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/16420176822471574499.
Full textAbstract:
碩士國立中正大學
物理學系暨研究所
103
In optical frequency modulations, acousto-optical modulator (AOM) is one of the important applications to demonstrate such nonlinear effect. Based on the momentum and energy conservation, frequency mixing in AOM is achieved by the interaction of photons and phonons. In the development of x-ray wave-mixing techniques, x-ray sum frequency generation (SFG) has been demonstrated by the interaction of x-ray photons and spatial charges induced by infrared photons in recent researches. The x-ray photons scattered by the oscillating charges at a specific frequency obtain the extra energy in the medium and make x-ray SFG possible. The purpose of this thesis is to develop an innovative soft x-ray frequency modulator based on the interaction of soft x-ray photons and surface plasmons. In this experiment, we propose to utilize an infrared laser to excite surface plasma wave on the surface of a tailor-made aluminum grating and irradiate the grating with a high harmonic generation (HHG) beam. The transmitted HHG is detected by a new design flat field spectrometer (FFS) to resolve the phenomenon of frequency modulation. In this experiment, we can not find any experimental signal from frequency modulations of soft x-rays due the instability of HHG source. However, we have successfully fabricated the free-standing grating for surface plasmon generations, measured the coupling efficiency of the grating and estimated the energy conversion efficiency of soft x-ray SFG. These results will be beneficial to achieve soft x-ray frequency modulation in the following experiment. Key Words: Surface Plasmon, Soft X-ray, Frequency Modulator
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Liao, Xinqing. "Surface Plasmon Polariton Based Polarization Modulators Using Metal-polymer Waveguides." Thesis, 2012. http://hdl.handle.net/1807/32256.
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A tunable polarization modulator based on the periodic metal strips embedded in a polymer waveguide is presented. The periodic metallic structure is analyzed by Finite Element simulation (COMSOL). The calculation results show that the giant birefringence is formed by the selective cut-off of TE polarization over TM polarization, which makes it possible to design an efficient polarization modulator with a short conversion length. The metallic strips are made by using four-layer lift-off fabrication technology. The transmission and group indices of TE and TM modes are measured. However, it is observed that TE and TM modes cut off at same time, which does not agree with our predictions. The reason for failure is that the change in refractive indices is different from what we expected, which makes the device perform in opposite way. Finally, further suggestions are provided to modify the design so that the device can achieve its expected function.
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Chu, Chih-Sheng, and 朱志昇. "Electro-Optic Light Modulators Based on Waveguide-Coupled Surface Plasmon Resonance." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/51196311676706254257.
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碩士國立中央大學
機械工程研究所
91
Due to the increasing demand for the development of light modulator with larger bandwidth and higher efficiency in the optical communication, in this thesis we present a novel ultrahigh efficiency and high dynamic response light modulator based on an external applied voltage to modulate the excitation degree of incident waveguide light in surface plasmons (SPs), known as the attenuation total reflection method (ATR method). This waveguide-coupled surface plasmon light modulator is fabricated by spin coating an organic electro-optic (E-O) polymer film onto the metal layer with suitable thickness of 30~40 nm, and then deposited a bottom metal electrode under the polymer. The molecular orientation of E-O polymer is aligned into noncentro-symmetry structure by applying contact poling process. When an external applied electric field created a linear variation of refractive index of poled E-O polymer according to the Pockels effect, the excitation degree of incident waveguide light in surface plasmons is changed and then the reflected light is modulated. Besides, we present in the thesis an optimizing design principle for efficient light modulator through the concentration of engery by waveguide coupled, surface plasmons, electro-optic effect, simulation, and theory analysis. To accurately determine the reflective index, attenuation coefficient, and the thickness of the metal layer, we analyzed the ATR spectra by techniques including Lorentzian equation analysis, Fresnel’s equation data-fitting and optimal linear data analysis. Alternatively, by using least square data-fitting techniques which employ two waveguide mode, we could calculate the refractive index and thickness of electro-optic polymer. We also estimated the attenuation coefficient of the polymer by anaylzing the reflection minimum of ATR spectrum. Finally, we calculated its actual electro-optic coefficient of this modulator by analyzing both E-O pockels effect and ATR spectrum. However, because the modulator fabricated in our experiment is not on optimum condition, the results so far show only 1% modulation in the intensity of the reflected light with driving voltage 30V. Finally, we present a novel and high efficiency electro-optic light modulators based on long range surface plasmon wave coupled with classical surface plasmon wave. Due to the excitation of surface plasmon wave, the energy is concentrated in the waveguide, so the efficiency could be improved. By simulation, it could effectively reduce driving voltage and increase the modulation index of 70 % with driving voltage 10 V.
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Chyou, Jin-Jung, and 邱進忠. "Electro-optic polymer light modulators based on multiple surface plasmon resonance effects." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/79118417966322255293.
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博士國立中央大學
機械工程研究所
94
The improvement on the efficiency of electro-optic (EO) light modulator can be achieved by the optimal design of EO modulating mechanism and the proper selection of EO materials. In this dissertation, two novel high efficiency EO modulators based on multiple surface plasmon resonance (SPR) effects are presented. One of the proposed EO polymeric modulators is based on a novel design in which the degree of coupling of the collimating monochromatic beam into the coupled waveguide-surface plasmon resonance (CWSPR) is electrically varied in order to enhance the modulation efficiency of the device. The other is so called double surface plasmon resonance (DSPR) and based on increasing coupling effect between two surface plasmon resonances via the optimization of the waveguide layer thickness. Both of EO modulators employed the Pockels effect possessed by the poled nonlinear optical organic polymer (NLOP) and the optimization of the thickness of EO thin film. By applying voltage across EO polymer film to vary the refractive index of the EO polymer, the degree of coupling of CWSPR and DSPR is altered and the reflectivity is modulated. The CWSPR EO modulator consists of a high refractive index prism, a thin metal film, a poled polymer layer, and metal electrode. By optimizing the thickness of the EO polymer, the coupling effect of the SPR and the waveguide coupled resonance (WCR) which induced by the Fabry-Perot (F-P) interference within EO polymer can be enhanced. As a result, the CWSPR EO modulator is able to operate with less modulation voltage and achieves better modulation efficiency. The DSPR EO modulator consists of a high refractive index prism, a thin metal film, a poled polymer layer, thin metal electrode, and EO film. In the same way, by optimizing the EO polymer thickness, the coupling effect of the short-range surface plasmon resonance induced at top metal interface and the long-range surface plasmon resonance induced at bottom metal interface will be enhanced and the modulator then yields a better efficiency. The EO polymer light modulator based on SPR-related principles offer the advantage of less insertion loss due to its shorter interaction length. This dissertation sequentially introduce the principles of SPR, the dispersion relation of multilayer system, the fundamentals of the modulator, the theoretical study and simulation concerning the relationship between the efficiency of modulator and the thickness of EO film. The determination of the refractive indexes and thicknesses for the various films, which is required for the fabrication of EO polymer modulator possessed with multilayer structure, can be achieved by employing the home-made SPR sensing technique and an improved data analysis method. In the similar approach, the SPR sensing technique is also capable of measuring the EO properties of the poled polymer film. This will greatly simplify experimental procedure. Since the NLOPs offer the advantages of having large EO constants, low dielectric constants, the simplicity to be fabricated, low cost, the diversity of synthesis and being compatible with integrated circuits, they are considered to be the most promising materials for the development of EO light modulator. Due to the aforementioned strengths offered by EO polymer, the EO polymers used in this project include two NLOP materials, one nonlinear optical organic polymer is a polymethyl methacrylate polymer (PMMA) side-chained with DANS (4, 4’-aminnonitroazobenzene) chromophore (DANS-PMMA) which synthesized and fabricated by our lab and the other is a side-chained EO polyimide with 2-(N-ethyl-4-(tricyanovinyl)anilino)ethanol chromophore. Based on using the foregoing principles, we have implemented two CWSPR EO modulators with these two NLOP materials. The modulators are characterized, and their performance is tested, in terms of the optical properties of the polymer thin film, the EO coefficient, the insertion loss, and the modulation index. Additionally, the dynamic response of the EO light modulator is also investigated and discussed.
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Chen, Meng-Ting, and 陳孟廷. "Study on surface plasmon resonance light modulator using a grating coupler." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/ss86zt.
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碩士國立虎尾科技大學
光電與材料科技研究所
98
In this study, we used two commercialized optical simulation software programs, EM Explorer and GSolver, to conduct simulation. Calculations in the simulation were based in a finite difference time domain (FDTD) and using the rigorous coupled wave analysis (RCWA) algorithm. To confirm whether if the calculations performed by the software consisted with the theory, the Kretschmann configuration and metal grating structure were simulated, respectively. The results were then compared with the theoretical calculations of the Fresnel equation. The results showed that the calculated results by the two software programs met with the theory. Further on we simulated and designed two types of grating coupler electro-optic modulators. The first type was an inverse grating structure, where simulation results showed the resonance angle was 22.98°, full width at half maximum (FWHM) was approximately 0.07°. When the refractive index of the EO polymer layer changed to 0.0015, the resonance angular shift was 0.06°. The incident angle was fixed at 22.98°, with an applied 9.09 V to enable the reflectivity change from 4 % to 69 %, which a voltage around 4.5 V can achieve 50% of modulation index; the second was a grating coupler with a long-range surface plasmon structure. Simulation results showed the resonance angle was 35.81°, FWHM approximately 0.05°. When the refractive index of the EO polymer layer changed to 0.0007 the resonance angular shift was 0.06°. The incident angle was fixed at 35.81°, with an applied 10.61 V to enable the reflectivity change from 1% to 60 %, which a voltage around 5 V can achieve 50 % of modulation index.
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TENG-HAN, YANG, and 楊登翰. "surface plasmon resonance with liquid crystal to resonate the modulator design characteristic research." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/07555418172243775626.
Full textAbstract:
碩士國防大學中正理工學院
電子工程研究所
94
The main purpose of this dissertation is to study the characteristic of the surface The main purpose of this dissertation is to study the design and application of optic-electro (O-E) modulator applied on the characteristic of the surface plasmon resonance. Through liquid crystal inspiration on surface plasmon resonance configuration, we investigate luminous intensity modulation of He-Ne Lasers. The research including: (1)Discuss the working voltage of the modulator. (2)Performance evaluations on the modulation of electrical signals. (3)Search the application in optic-electro (O-E) modulator. The simulation results funded that after incident light reflective through LC O-E modulator, which inspirited by the surface plasmon resonance, we could modulate luminous intensity in the way of inputting an electrical signal. Under this situation we used external voltage to modulate intensity variation of reflective light. The higher voltage is, the stronger reflective light was. On the other side, the lower of voltage, the weaker of reflective light. The results are applied on the O-E modulator and the modulated index of the LC SPR O-E modulator increases with higher voltage. When the voltage is increased to 10V, the modulated index of red laser (wavelength = 632.8nm) can be up to about 66%. In this research, the LC SPR O-E modulator with a broadband operating is around 1~10MHz. The LC O-E modulator under our design can transmits different broadband signal at the same time. In the thesis, the modulator can modulate voltage by DC Offset to improve the characteristic of output optical signal. Output optical signal comes out various distortions upon various applied working frequencies; even comes out the effect of harmonic generation. This phenomenon can be improved effetely by DC Offset modulation. Furthermore, it can apply on signal transmittal application practically. As a result, the SPR O-E device is in highly possibility. The application on other field is also our focus direction in the future. Thus, we respect further study could make optic-electro (O-E) in highly performance with high frequency, low voltage, high stability and practicability.