Plasmonic nanostructures can enhance light-matter interactions in the subwavelength domain, which is useful for photodetection, light emission, optical biosensing, and spectroscopy. However, conventional plasmonic devices are optimized to operate in a single wavelength band, which is not efficient for wavelength-multiplexed operations and quantum optical applications involving multi-photon nonlinear processes at multiple wavelength bands. Overcoming the limitations of single-resonant plasmonics requires development of plasmonic devices that can enhance the optical interactions at the same locations but at different resonance wavelengths. This dissertation comprehensively studies the theory, design, and applications of such devices, called "multiresonant plasmonic systems with spatial mode overlap". We start by a literature review to elucidate the importance of this topic as well as its current and potential applications. Then, we briefly discuss the fundamentals of plasmonic resonances and mode hybridization to thoroughly explore, classify, and compare the different architectures of the multiresonant plasmonic systems with spatial mode overlap. Also, we establish the black-box coupled mode theory to quantify the coupling of optical modes and analyze the complicated dynamics of optical interactions in multiresonant plasmonic systems. Next, we introduce the nanolaminate plasmonic crystals (NPCs), wafer-scale metamaterials structures that support many (>10) highly-excitable plasmonic modes with spatial overlap across the visible and near-infrared optical bands. The enabling factors behind the NPC's superior performance as multiresonant systems are also theoretically and experimentally investigated. After that, we experimentally demonstrate the NPCs application in simultaneous second harmonic generation and anti-Stokes photoluminescence (ASPL) with controllable nonlinear emission properties. By designing specific non-linear optical experiments and developing advanced ASPL models, this work addresses some important but previously unresolved questions on the ASPL mechanism as well. Finally, we conclude the dissertation by discussing the potential applications of out-of-plane plasmonic systems with spatial mode overlap in wavelength-multiplexed devices and presenting some preliminary results. / Doctor of Philosophy / Emergence of electronic devices such as cellphones and computers has revolutionized our lifestyles over the past century. By manipulating the flow/storage of electrons at the nanometer scale, electronic components can be very compact, but their speed and energy performance is ultimately limited due to ohmic losses and finite velocity of the electrons. In parallel, photonic devices and circuits have been proposed that by molding the flow of light can overcome the mentioned limitations but are not as integrable as their electronic counterparts. Plasmonics is an emerging research field that combines electronics and photonics using nanostructures that can couple the light waves to the free electrons in metals. By confining the light at deep subwavelength scales, plasmonic devices can highly enhance the light-matter interactions, with applications in ultrafast optical communications, energy-harvesting, optical sensing, and biodetection. Conventionally, plasmonic devices are optimized to operate with a single light color, which limits their performance in wavelength-multiplexed operations and ultrafast non-linear optics. For such applications, it is far more efficient to use the more advanced "multiresonant plasmonic systems with spatial mode overlap" that can enhance the optical interactions at the same locations but for multiple light colors. This dissertation comprehensively studies these systems in terms of the fundamental concepts, design ideas, and applications. Our work advances the plasmonic field from both science and technology perspectives. In particular, we explore and classify the strategies of building multiresonant plasmonic systems with spatial mode overlap for the first time. Also, we establish the black-box coupled mode theory, a novel framework for analysis and design of complicated plasmonic structures with optimized performance. Furthermore, we introduce the "nanolaminate plasmonic crystals" (NPCs), large area and cost-effective devices that can enhance the optical processes for both visible and near-infrared lights. Finally, we demonstrate NPCs ability in simultaneous frequency-doubling and broadband emission of light and come up with advanced theoretical models that can explain the light generation and color conversion in plasmonic devices.

Made available in DSpace on 2016-12-12T17:38:37Z (GMT). No. of bitstreams: 1 CLAUDIO EDUARDO SOARES.pdf: 20046362 bytes, checksum: 135e6d7d3a6f98bef9152afe645904c4 (MD5) Previous issue date: 2011-04-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The controllers based on the internal model principle have found emphasis on control systems due to its ability to perform robust tracking of signals whose generator models are embedded in their internal structures. Controllers with integral, resonant and repetitive terms are examples of this principle. However, the control systems are subject to physical limitations that restrict their operation under certain conditions. The amplitude saturation of the control action is the most common type of restriction found in real systems. The impacts of the saturation of control action are known as windup and its consequences for systems with integral action have already been exhaustive examined. However, the impacts of saturation of control action are not restricted to this type of controller. Other controllers based on the internal model principle are also affected by the windup phenomenon due to saturation of the action control. The impacts of the windup phenomenon for resonant, multi-resonant and repetitive controllers are investigated in this dissertation and an anti-windup technique is suggested to mitigate the impacts of the control saturation on these controllers. The proposed anti-windup technique is based on the conditional integration technique, originally developed for the controllers with integral action, and it is named conditional update. Simulation results are presented to validate the proposed technique. / Os controladores baseados no princípio do modelo interno têm encontrado destaque no controle de sistemas devido a sua capacidade de realizar o rastreamento robusto dos sinais cujos modelos geradores estejam embutidos nas suas estruturas internas. Os controladores com ação integral, ressonantes e repetitivos são exemplos da aplicação deste princípio. Contudo, os sistemas de controle estão sujeitos a limitações físicas que restringem suas condições de operação. A saturação da amplitude da ação de controle é o tipo de limitação mais comum encontrada nos sistemas reais. Os impactos da saturação da ação de controle são conhecidos como windup e suas consequências para os sistemas com ação integral já foram exaustivamente analisadas. Porém, os impactos da saturação da ação de controle não se restringem a este tipo de controlador. Outros controladores baseados no princípio do modelo interno também são afetados pelo fenômeno windup decorrente da saturação da ação de controle. Os impactos do fenômeno windup sobre os controladores ressonantes, multiressonantes e repetitivos são investigados nesta dissertação e uma técnica anti-windup é sugerida para atenuar os impactos da saturação da ação de controle sobre estes controladores. A técnica anti-windup proposta é baseada na técnica da integração condicional, originalmente desenvolvida para os controladores com ação integral e, por isso, denominada de atualização condicional. Resultados de simulação são apresentados para validação da técnica proposta.

High frequency link power converters for DC – 3Φ AC applications are investigated. Low cost, reduced size, galvanic isolation and efficient large boosting of voltage level are the key motivations behind the selection of such topologies. This thesis proposes high frequency link 3Φ inverters for three wire and four wire systems. The proposed topologies have the simplest power circuit configuration and commutation requirements among all high frequency link topologies reported in the literature. A full load efficiency greater than 90% is achieved with a passive snubber. The effect of various circuit non-idealities are common and important for desirable performances of these topologies. A few such issues are highlighted. Firstly, the special commutation requirement of the power circuit causes a non-linear distortion in the output voltages and thus makes the gain of the power converter time varying. A simple compensation technique is adopted to mitigate the problem. Secondly, the high frequency transformer should operate with only switching frequency component. However, in the practical situations a significant amount of low frequency component gets injected into the transformer and results in peaky transformer magnetizing current unless it is over designed. A suitable measure is incorporated in the proposed topologies to achieve a magnetic protection. The power circuit topology is used as stand-by AC power supply. These are of interest for Uninterruptible Power Supply (UPS) and Micro-grid applications. One of the main objectives of such supplies is to provide a high quality and highly reliable power to the connected loads. A voltage regulation loop based on proportional + multiresonant controller is proposed to achieve excellent quality of the output voltage with unbalanced and nonlinear loadings. The factors influencing regulation and stability of the voltage waveform are identified and necessary modifications are carried out to improve the performance. The potential of this voltage regulation loop along with P/Q droop technique and a simple resistive virtual output impedance loop is exploited to achieve decentralized paralleling of inverters. A trade off between the output voltage power quality and the sharing accuracy is examined. The total harmonic distortion and degree of unbalance in the output voltage waveform are experimentally measured well below the specified limit for stand alone AC supplies with an excellent sharing accuracy. Some of the grid interactive modes are addressed for the completeness of the work. A shunt compensator system and a double conversion system based on the same high frequency link converter are experimentally evaluated. These systems can find their application in UPS systems. A few important observations on the power circuit performances are indicated.