This document presents the modelling and characterization of novel photonic devices based on periodic arrays of multiwalled carbon nanotubes. Multiwalled carbon nanotubes are mostly metallic in nature and interesting plasmonic effects are observed when nanotubes are grown close together, with spacing of about 400 nm. The effective electronic mass on the nanotubes changes, due to mutual coupling between them and they start displaying dielectric properties which are inherently different from the their own, forming metamaterials. We present a plasmonic high pass filtering application of carbon nanotube based metamaterials. Some promising modelling and experimental results are demonstrated showing a strong cut-off filtering effect at the plasma frequency displayed by the periodic arrays of multiwalled carbon nanotubes. The artificial negative dielectric constant displayed by the nanotube arrays was also successfully utilised for producing micron-scaled applications like optical waveguides and negative lenses for overcoming the diffraction limit. The fabrication of these optical devices using the arrays of silicon nanopillars was also considered. These arrays when fabricated at nano-scaled dimensions (of about 400 nm) present a greater degree of periodicity and require a simpler fabrication process compared to carbon nanotubes. We report the detailed computational analysis on silicon nanopillars based photonic crystals, waveguides and metamaterials which operate well within in the optical regime. However, due to the fabrication limitations, the fabricated Si nanopillars presented an inverted cone shape profile along their lengths. These inverted nanocone structures were successfully utilised for enhancing reflection from Si surfaces for applications in photovoltaic devices. Lastly we present a novel application of carbon nanotube arrays for producing micron-scale Fresnel lens arrays. Forests of carbon nanotubes were utilised as absorbing media on top of a bare silicon substrate. Optical diffraction of light across the nanotube forests produced strong focusing of light, at focal lengths of order 125 microns. Numerical simulations were in excellent agreement with the measured results.

In order to harness the enormous potential of schemes in optical quantum information processing, readily scalable photonic circuits will be required. A major obstacle for this scalability is the monolithic integration of quantum light sources with the photonic circuit on a single chip. This dissertation presents the experimental demonstration of different in-plane single photon sources that allow for this integration with planar light circuits. To this end, the spontaneous recombination of excitons in single indium arsenide quantum dots was exploited to generate single photons. The emission into on-chip waveguides was achieved by the use of advanced two-dimensional photonic crystal structures. First, slow-light effects in a unidirectional photonic crystal waveguide were exploited to achieve on-demand single photon emission with a rate of up to 18.7 MHz, corresponding to a remarkable estimated internal device efficiency of up to 47%. Waveguide-coupled L3 defect cavities with record Q-factors of up to 5150 were then studied for improved Purcell enhancement of the emission, and in-plane single photon generation from such a device was demonstrated. Finally, an electrically tunable, integrable quantum light source with a total tuning range of 1.9 nm was demonstrated by exploiting the quantum-confined Stark effect in an electrical PIN diode. These results are the first demonstrations of in-plane single photon emission at optical wavelengths and mark an important cornerstone for the realisation of fully integrated quantum photonic circuits in optical quantum information science.

No description available.

La possibilité de fabriquer des dispositifs optiques pour la détection d’interactions chimiques,sans marquage et en temps réel, présente un intérêt croissant. Notamment, les cristaux photoniques(CPh) présentent un fort potentiel pour une telle application. Contrairement au silicium, majoritairementexploité pour la réalisation de telles structures, le diamant possède l’avantage d’avoir unesurface carbonée biocompatible permettant une fonctionnalisation covalente et stable de biomoléculesspécifiques. Dans ce contexte, cette thèse vise à étudier la potentialité qu’offre ce matériau pour la réalisationde CPh 2D destinés à des applications de biodétection. Pour cela, une plateforme photoniquemonolithique compacte, intégrable sur silicium et optimisée pour un fonctionnement aux longueursd’onde proches de 1.55 μm a été développée. Une géométrie de cavité à fente a été retenue afin demaximiser la sensibilité des structures photoniques à leur environnement extérieur. Des méthodesnumériques ont permis de préciser les paramètres géométriques des CPh. Des procédés de microstructurationde films minces de diamant polycristallin sur substrat silicium 2 pouces ont été développéset optimisés, pour aboutir à la réalisation de CPh caractérisés par des facteurs de qualité pouvantatteindre 6500. Deux procédés technologiques spécifiques aux films de diamant polycristallin ont notammentété développés : un procédé de lissage et un procédé de transfert de films de diamant surisolant. La sensibilité optique des CPh en diamant à une modification chimique de surface a ensuiteété étudiée et a tout d’abord montré une forte dépendance de leurs performances optiques à de simplesvariations des terminaisons chimiques du matériau. Par la suite, une preuve de concept de détectionsurfacique de protéines en milieu liquide par les CPh en diamant a été réalisée en utilisant le systèmede bioreconnaissance biotine/streptavidine, donnant une limite de détection estimée pour le systèmeà 10 μg/mL. Enfin, des travaux préliminaires de détection dans le visible ont été engagés via la réalisationde cavités à CPh fonctionnant à 600 nm, présentant déjà des facteurs de qualité dépassant les1500. / The ability to fabricate optical devices enabling the real time detection of chemical interactions,avoiding the use of markers, has motivated a growing interest. In particular, photonic crystals (PhC)based structures are promising candidates for such applications. Unlike silicon, that has currentlybeen used for most of these demonstrations, diamond offers a high stability and a versatile carbonsurface that can be functionalized to covalently bond specific organic or bio-molecules on its surface.In this context, this thesis aims at studying the interests of diamond for the realization of novel 2DPhC dedicated to biodetection applications. A fully monolithic compact photonic platform, integratedon silicon and optimized to work at wavelength of 1.55 μm was developed. A geometry consistingin a slotted cavity was chosen in order to maximize the sensitivity of such photonic structures totheir environment. Numerical methods allowed to determine the geometrical parameters of the PhC.Diamond microstructuration processes of polycrystalline diamond films deposited on two-inch siliconwafers were developed and optimized for the realization of PhC cavities with quality factors up to6500. Two technological processes specifically dedicated to polycrystalline diamond were developed : asmoothing process and a diamond layer on insulator integration by wafer bonding technology process.The optical sensitivity of diamond PhCs to simple surface modifications was studied and showed that,depending on the chemical surface termination, these diamond PhCs exhibit a strong modification oftheir spectral features. A proof of concept for surface detection in a water environment was realizedusing the biotin/streptavidin biorecognition system. The detection limit of the system was estimatedto be 10 μg/mL. Finally, first steps to detection in the visible range were made with the realization ofPhC working at 600 nm and exhibiting Q factors exceeding 1500.

Orientador: Solange Bessa Cavalcanti / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-14T09:40:15Z (GMT). No. of bitstreams: 1 LozadaVera_JohnJairo_M.pdf: 3582168 bytes, checksum: b939d006da96c563046ce0074e25f72e (MD5) Previous issue date: 2009 / Resumo: Estuda-se a interação entre pulsos ópticos ultracurtos e materiais com band gap fotônico, considerando-se a propagação de luz através de estruturas unidimensionais, compostas de uma super-rede dielétrica periódica cuja célula unitária consiste em um par de camadas com diferentes índices de refração n1e n2, respectivamente. Em particular considera-se o caso em que n2, por exemplo, é um material com não linearidade X (3). É bem sabido que a largura e a localização dos band gaps dependem fundamentalmente do contraste entre os índices de refração d n = | n1 - n1 | e, atribuindo-se a n2 um índice de refração dependente da intensidade, conseguimos controlar dinamicamente a largura do band gap com o pulso de luz incidente. Portanto, a idéia básica é investigar a dinâmica de propagação nas vizinhanças de um band gap dependente da intensidade para aplicações importantes no projeto de dispositivos fotônicos, como por exemplo limitadores de luz e switches puramente ópticos. Dentro do formalismo de Maxwell, experimentos computacionais são feitos considerando a propagação de campos ópticos através de super-redes que possuem não linearidades do tipo Kerr, assim como saturável. Esta última é importante para a descrição da interação com pulsos muito intensos já que neste caso a mudança induzida no índice de refração depende de não linearidades de ordem mais alta e, como consequência, alcança uma saturação. Este modelo é apropriado para descrever materiais tais como vidros dopados com semicondutores (e.g. CdS 1-x Sex) polímeros orgânicos, que possuem propriedades ópticas altamente não lineares. A propagação da onda é resolvida usando uma versão modificada no domínio do tempo do método standard fast Fourier Beam Propagation Method (FFT-BPM) com um passo adaptativo, que pode manejar transmissão, difração e, especialmente, reflexões das ondas electromagnéticas causadas por descontinuidades no índice de refração, com a vantagem de não requerer a introdução de condições de contorno adicionais. / Abstract: The interaction of ultrashort optical pulses with photonic band gap materials has been studied by considering light propagation through one-dimensional photonic band gap structures, composed of a periodic multilayer stack of dielectric materials whose unitary cell consists of a pair of layers with different refractive indices n1and n2, respectively. One of these, say n2, is doped with a X (3)nonlinear material. It is well known that band gaps widths and locations depend fundamentally on the refractive index contrast d n = | n1 - n1 | and, by assigning to n2 an intensity dependent refractive index, one is bound to dinamically control the band gap width with the incident light pulse. Therefore, the basic idea here is to investigate the dynamics of propagation in the neighborhood of such an intensity-dependent band gap for important applications in the design of all-optical photonic devices such as limiters and switches. Within the framework of Maxwell's equations, a numerical investigation is made by considering the propagation of optical fields through multilayers with a Kerr, as well as a saturable, type of nonlinearity. The latter is important for the description of the interaction with high field strength pulses because in this case the field-induced change in the refractive index is influenced by higher-order nonlinearities and, as a consequence, this change becomes saturated. This model is appropriate to describe materials such as semiconductor-doped glasses (e.g. CdS 1-x Sex) and organic polymers, which have high nonlinear optical properties. The wave propagation is solved using a time-domain modified version of the standard fast Fourier Beam Propagation Method (FFT-BPM) with an adaptive step size, which can handle transmission, diÿraction and, especially, reflection of electromagnetic waves caused by discontinuities on the refractive index, with the advantange of not requiring the introduction of additional boundary conditions. / Mestrado / Ótica / Mestre em Física

[EN] Metamaterials are periodic structures whose unit cells are small compared to the wavelength at the operating frequency. Under these conditions, these artificial materials can be considered as homogeneous media whose constitutive parameters depend on the characteristics of the unit cells. The discovery of metamaterials opened a new research field that has produced many works with microwaves, optical waves and acoustic waves. In this context, the main goal of this thesis is the study of new structures based on metamaterials that allow controlling of electromagnetic energy. In particular, new solutions for localization and absorption of electromagnetic waves are proposed. The thesis has been developed in the Wave Phenomena Group of the Polytechnic University of Valencia and in collaboration with the Group of Acoustic and Electromagnetic Metamaterials at the University of Exeter. The problems studied in the first part of this thesis are energy harvesting for subsequent absorption, wireless power transfer and new systems that can be used as position sensors. To solve these problems a new type of cylindrical, multilayer and anisotropic structures known as Radial Photonic Crystals are used. The radial dependence of the constitutive parameters generates, in these structures, a behavior like a one dimensional photonic crystals. Among the results obtained with these structures, it is included the first experimental demonstration of a Radial Photonic Crystals based resonator. Absorption of electromagnetic waves by thin layers of lossy materials is the second topic of this thesis. The main target is the theoretical and experimental study of the absorption enhancement in thin layers by using two-dimensional periodic structures, also called metasurfaces. Specifically, we studied the effects of a square lattice of coaxial cavities covered by a thin layer of lossy material. As a result, an enhancement of the absorption peaks that can produce total absorption is achieved. The semi-analytical study of this structure has allowed obtaining expressions that control the position of the absorption peak and its amplitude; which have helped to develop a design methodology for total absorption systems. / [ES] Los metamateriales son estructuras periódicas cuyas celdas unidad son muy pequeñas en comparación con la longitud de onda a la frecuencia de trabajo. Bajo estas condiciones, estos materiales artificiales pueden considerarse como medios homogéneos cuyos parámetros constitutivos dependen de las características de las celdas unidad que los componen. La aparición de los metamateriales abrió un nuevo campo de investigación que ha generado multitud de trabajos en las líneas de microondas, óptica y acústica. En este contexto, el objetivo principal de esta tesis es el estudio de nuevas estructuras basadas en metamateriales que permitan el control de la energía electromagnética. En particular, plantea nuevas soluciones para problemas de localización y absorción de ondas electromagnéticas. La tesis ha sido desarrollada en el Grupo de Fenómenos Ondulatorios de la Universidad Politécnica de Valencia y en colaboración con el Grupo de Metamateriales Acústicos y Electromagnéticos de la Universidad de Exeter. Los problemas estudiados en la primera parte de esta tesis son la concentración de energía para su posterior absorción, la transferencia inalámbrica de potencia y nuevos sistemas capaces de ser empleados como sensores de posición. Para la solución de estos problemas se emplean un nuevo tipo de estructuras cilíndricas, multicapa y anisótropas conocidas como Cristales Fotónicos Radiales. La dependencia radial de los parámetros constitutivos de los materiales que componen cada una de sus capas genera, en estas estructuras, un comportamiento similar al de los cristales fotónicos unidimensionales. Entre los resultados obtenidos con estas estructuras, cabe destacar la primera demostración experimental de un resonador basado en Cristales Fotónicos Radiales. La absorción de ondas electromagnéticas por capas delgadas de materiales con pérdidas es el segundo tema tratado en esta tesis. El objetivo principal es el estudio teórico y experimental del aumento de la absorción en capas delgadas mediante el uso de estructuras periódicas bidimensionales, también llamadas metasuperficies. En concreto, se han estudiado los efectos de una red cuadrada de cavidades coaxiales sobre la que se coloca una capa delgada de un material con pérdidas. Como resultado, se consigue un aumento de la absorción que permite obtener picos de absorción total. El estudio semianalítico de esta estructura ha permitido obtener expresiones que controlan la posición del pico de absorción y su amplitud; las cuales han permitido desarrollar una metodología de diseño para sistemas de absorción total. / [CAT] Els metamateriales són estructures periòdiques en els que les cel·les unitat són molt xicotetes en comparació amb la longitud d'ona a la freqüència de treball. Tenint en consideració aquestes condicions, aquestos materials artificials poden considerar-se com a mitjans homogenis en els que els paràmetres constitutius depenen de les característiques de les cel·les unitat que els componen. A més, l'aparició dels metamateriales va obrir un nou camp d'investigació que ha generat multitud de treballs en les línies de microones, òptica i acústica. En aquest context, l'objectiu principal d'aquesta tesi és l'estudi de noves estructures basades en metamateriales que permeten el control de l'energia electromagnètica. En particular, planteja noves solucions per a problemes de localització i absorció d'ones electromagnètiques. La tesi ha sigut realitzada en el Grup de Fenòmens Ondulatoris de la Universitat Politècnica de València i en col·laboració amb el Grup de Metamateriales Acústics i Electromagnètics de la Universitat d'Exeter. Els problemes analitzats en la primera part de la tesi són la concentració d'energia per a la seua posterior absorció, la transferència inalàmbrica de potència i nous sistemes capaços de ser empleats com a sensors de posició. Per a la solució dels problemas identificats s'utilitza un nou tipus d'estructures cilíndriques, multicapa i anisòtropes conegudes com a Cristalls Fotónics Radials. La dependència radial dels paràmetres constitutius dels materials que componen cadascuna de les seues capes genera, en aquestes estructures, un comportament semblant al dels Cristalls Fotónics Unidimensionals. Entre els resultats obtinguts, cal destacar la primera demostració experimental d'un ressonador basat en Cristalls Fotónics Radials. Pel que respecta a la segon part de la tesi, l'absorció d'ones electromagnètiques per capes primes de materials amb pèrdues és tema tractat. L'objectiu principal és l'estudi teòric i experimental de l'augment de l'absorció en capes primes per mitjà de l'ús d'estructures periòdiques bidimensionals, també denominades metasuperficies. En concret, s'han examinat els efectes d'una xarxa quadrada de cavitats coaxials sobre la qual es col·loca una capa prima d'un material amb pèrdues. Com a resultat, s'aconseguix un augment de l'absorció que permet obtindre pics d'absorció total. Així mateix, l'estudi semi-analític d'aquesta estructura ha permés obtindre expressions que controlen la posició del pic d'absorció i la seua amplitud; les quals han permés desenvolupar una metodologia de disseny per a sistemes d'absorció total. / Díaz Rubio, A. (2015). Control of electromagnetic energy by metamaterials [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/54137 / TESIS

Patterning graphene with a spatially periodic potential provides a powerful means to modify its electronic properties. In particular, in twisted bilayers, coupling to the resulting moiré superlattice yields an isolated flat band that hosts correlated many-body phases. However, both the symmetry and strength of the effective moiré potential are constrained by the constituent crystals, limiting its tunability. Here, we have exploited the technique of dielectric patterning⁶ to subject graphene to a one-dimensional electrostatic superlattice (SL). We observed the emergence of multiple Dirac cones and found evidence that with increasing SL potential the main and satellite Dirac cones are sequentially flattened in the direction parallel to the SL basis vector, behavior resulting from the interaction between the one-dimensional SL electric potential and the massless Dirac fermions hosted by graphene. Our results demonstrate the ability to induce tunable anisotropy in high-mobility two-dimensional materials, a long-desired property for novel electronic and optical applications. Moreover, these findings offer a new approach to engineering flat energy bands where electron interactions can lead to emergent properties. The photon analog of electronic superlattice is photonic crystals. Efficient control of photons is enabled by hybridizing light with matter. The resulting light-matter quasi-particles can be readily programmed by manipulating either their photonic or matter constituents. Here, we hybridized infrared photons with graphene Dirac electrons to form surface plasmon polaritons (SPPs) and uncovered a previously unexplored means to control SPPs in structures with periodically modulated carrier density. In these photonic crystal structures, common SPPs with continuous dispersion are transformed into Bloch polaritons with attendant discrete bands separated by bandgaps. We explored directional Bloch polaritons and steered their propagation by dialing the proper gate voltage. Fourier analysis of the near-field images corroborates that this on-demand nano-optics functionality is rooted in the polaritonic band structure. Our programmable polaritonic platform paves the way for the much-sought benefits of on-the-chip photonic circuits.

Microphotonics has been offering a body of ideas to prospective applicationsin optics. Among those, the concept of photonic integrated circuits (PIC’s) has recently spurred a substantial excitement into the scientific community. Relisation of the PIC’s becomes feasible as the size shrinkage of the optical elements is accomplished. The elements based on photonic crystals (PCs) represent promising candidacy for manufacture of PIC’s. This thesis is devoted to tailoring of optical properties and advanced modelling of two types of photonic crystals: (Bi3Fe5O12/Sm3Ga5O12)m and (TiO2/Er2O3)m potentially applicable in the role optical isolators and optical amplifiers, respectively. Deposition conditions of titanium dioxide were first investigated to maximise refractive index and minimise absorption as well as surface roughness of titania films. It was done employing three routines: deposition at elevated substrate temperatures, regular annealing in thermodynamically equilibrium conditions and rapid thermal annealing (RTA). RTA at 500 oC was shown to provide the best optical performance giving a refractive index of 2.53, an absorption coefficient of 404 cm−1 and a root-mean-square surface roughness of 0.6 nm. Advanced modelling of transmittance and Faraday rotation for the PCs (Bi3Fe5O12/Sm3Ga5O12)5 and (TiO2/Er2O3)6 was done using the 4 × 4 matrix formalism of Višňovský. The simulations for the constituent materials in the forms of single films were performed using the Swanepoel and Višňovský formulae. This enabled generation of the dispersion relations for diagonal and off-diagonal elements of the permittivity tensors relating to the materials. These dispersion relations were utilised to produce dispersion relations for complex refractive indices of the materials. Integration of the complex refractive indices into the 4 × 4 matrix formalism allowed computation of transmittance and Faraday rotation of the PCs. The simulation results were found to be in a good agreement with the experimental ones proving such a simulation approach is an excellent means of engineering PCs.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18284号 / 工博第3876号 / 新制||工||1595(附属図書館) / 31142 / 京都大学大学院工学研究科電子工学専攻 / (主査)教授 野田 進, 教授 川上 養一, 教授 藤田 静雄 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21270号 / 工博第4498号 / 新制||工||1700(附属図書館) / 京都大学大学院工学研究科電子工学専攻 / (主査)教授 野田 進, 教授 藤田 静雄, 教授 川上 養一 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM