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<p>Wavelength division multiplexing (WDM) is the key technology of the current generation fiber-optics network. To build agile and intelligent next generation optical networks, optical wavelength conversion and signal regeneration are crucial new functions under intense research and development. These new functions call for innovative, low cost and high performance optoelectronic devices. One of such enabling devices is quantum-well electroabsorption modulators (EAM) that are appealing in terms of structural simplicity and low noise and are potentially advantageous on high-speed operation and low power consumption. The goal of this thesis is to systematically study EAM for optical signal functions in optical networks from various perspectives, including fundamental device physics, comprehensive models, innovative design, and experimental prototyping.</p> <p>After the first chapter of introduction, Chapter 2 and 3 are devoted to device models. In Chapter 2, a self-consistent and physics-based model has been developed for two key nonlinear optical mechanisms in quantum-well EAM: exciton saturation and electric field screening. Presented in Chapter 3 is a simplified but efficient model for EAM with a feature of handling strong electric field.</p> <p>Next, the fundamental physics relevant to nonlinear EAM are studied in Chapter 4 and 5. Exciton state mixing effects on intersubband transitions in quantum well have been investigated in Chapter 4 and a drastic different picture from that of the previous studies has been revealed. Studies have also been done in Chapter 5 on valence band mixing effects in exciton capture and escape in quantum well structures. And it is found that much faster capture and escape processes can be resulted from the band mixing effects.</p> <p>Then, the two key design issues of nonlinear EAM have been addressed. In Chapter 6, different saturation dynamics of electrons and holes in quantum wells have been thoroughly analyzed and utilized to achieve the best compromise between high-speed and low power consumption of EAM in optical wavelength conversion and signal regeneration. In Chapter 7, the polarization issue of transverse electric (TE) mode and transverse magnetic (TM) mode is addressed from two different perspectives: design for the most effective optical saturation by using TM mode absorption and design for TE and TM polarization insensitive operation.</p> <p>Finally, Chapter 8 presents the results of experimental proto typing on the design concept to enhance exciton absorption saturation using light-hole excitation through TM optical mode.</p> / Doctor of Philosophy (PhD)

The demand for bandwidth is increasing vigorously. Thus wired network is using fiber optic telephone line instead of coaxial cable. The concept of Fiber to the Home (FTTH) is really coming into picture. Few countries like Japan, Korea etc are leading in this technology. But now the major challenge is how to provide the high speed internet connection wirelessly. Thus the change is to integrate the wireless and optical fiber communication. / Wireless Optical Communication

Los moduladores son elementos claves para la transmisión de la señal y el procesamiento de la información. Las técnicas de fabricación avanzadas "complementary metal-oxide semiconductor" (CMOS) permiten reducir drásticamente las dimensiones de estos dispositivos de interés para la implementación a gran escala en un chip de silicito a bajo coste. El trabajo realizado en esta tesis se centra en el diseño, la fabricación y la caracterización de estructuras de onda lenta con el objetivo de realizar moduladores compactos y eficientes integrados en un chip de silicio. El trabajo se divide en cuatro capítulos y un capítulo de conclusión y perspectivas. El capítulo uno introduce los fundamentos de física del estado sólido y de los mecanismos básicos de propagación guiada de la luz por reflexión total interna. El capítulo dos presenta los parámetros importantes de los moduladroes electro-ópticos así como un trabajo de recopilación de todos los mecanismos físicos que pueden ser empleados para modular la luz en silicio. Además, se presenta el estado del arte de los moduladores basados en silicio. El capítulo tres presenta el diseño , fabricación y caracterización de un modulador electro-óptico en silicio compacto y eficiente basado en el efecto de onda lenta en una estructura periódica unidimensional integrada, cuya geometría, similar a la de una red de Bragg, permite reducir la velocidad de grupo de un paquetes de ondas. Dicho efecto, se emplea para incrementar la interacción luz-materia y por lo tanto la eficiencia del modulador electro-óptico. El capítulo cuatro demuestra experimentalmente que dicha guía unidimensional periódica puede ser mejorada a fin de conseguir que el efecto de baja velocidad de grupo suceda en un rango mayor de longitudes de onda para posibles aplicaciones como la multiplexación por división de longitudinal de onda. En el capítulo cinco, se proporcionan conclusiones y perspectivas sobre el trabajo realizado. / Brimont ., ACJ. (2011). Towards Compact and High Speed Silicon Modulators [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/14345

Silicon photonics is one of the most exciting and fastest growing photonic technologies in recent years. The salient feature of this technology is its compatibility with the mature silicon IC manufacturing based on complementary metal-oxide semiconductor (CMOS) processes widely used in microelectronic industry. Another motivation is the availability of high-quality silicon-on-insulator (SOI) planar waveguide circuits that offer strong optical confinement due to the high index contrast between silicon (n=3.45) and SiO2 (n=1.45). This opens up miniaturization and very large scale integration of photonic devices allowing photonic integrated circuits for a wide range of applications and markets, from optical telecommunications to bio-photonic devices or precise fibre sensors. Optical modulators are key building-blocks for high speed signal transmission and information processing in any photonic interconnection solution. The work developed in this thesis, as part of the objectives of the European project HELIOS in which it is framed, is essentially focused on realizing compact and efficient modulators integrated on silicon chips. The thesis consists of three main chapters as well as the concluding section on the work accomplished. Chapter one is aimed at giving a general description of the benefits of using silicon photonics, showing its challenges and opportunities as well as at giving a deeply overview of all issues related to the electro-optic modulation. Chapter two is devoted to develop silicon modulators with high features for digital applications. Specifically, new optical structures different to the conventional ones are presented with the aim of enhancing the modulation performance or at least several critical parameters in the modulation. Chapter three is dedicated to the analog applications. The concept of microwave photonics is described as well as different researches carried out in the analog scope for application in the field of integrated microwave photonics, all of them using CMOS-compatible electro-optic silicon modulators which validate the potential of silicon photonics as a promising approach for enabling the development of integrated microwave photonics applications. Finally, conclusions on the work realized are provided in Chapter 4. / La fotónica de silicio es una de las tecnologías fotónicas que está experimentando un crecimiento más excitante y rápido en los últimos años. La característica más destacada de esta tecnología es su compatibilidad con las maduras técnicas de fabricación de circuitos integrados de silicio basadas en los procesos ¿complementary metal-oxide semiconductor¿ (CMOS) ampliamente utilizados en la industria microelectrónica. Otra motivación es la disponibilidad de circuitos de guía de ondas planas de silicio sobre aislante (SOI) de alta calidad que ofrecen un fuerte confinamiento óptico debido al alto contraste índices entre el silicio (n=3,45) y el SiO2 (n = 1,45). Esto abre las puertas a la miniaturización y a la integración a gran escala de dispositivos fotónicos lo que resulta en circuitos fotónicos integrados para una amplia gama de aplicaciones y mercados, desde telecomunicaciones ópticas a dispositivos bio-fotónicos o sensores de fibra precisos. Los moduladores ópticos son elementos básicos fundamentales para la transmisión de señales a alta velocidad y el procesado de información en cualquier solución de interconexión fotónica. El trabajo desarrollado en esta tesis, como parte del los objetivos del proyecto Europeo HELIOS en el que está enmarcada, se centra fundamentalmente en realizar moduladores compactos y eficientes, integrados en chips de silicio. La tesis consiste en 3 capítulos principales así como una sección de conclusiones del trabajo conseguido. El capítulo uno está destinado a dar una descripción general de los beneficios del uso de la fotónica de silicio, mostrando sus retos y oportunidades, así como a dar una visión profunda de todos los aspectos relacionados con la modulación electro-óptica. El capítulo dos está dedicado a desarrollar moduladores de silicio de altas prestaciones para aplicaciones digitales. Específicamente, se presentan nuevas estructuras ópticas diferentes a las convencionales con el objetivo de mejorar el rendimiento de la modulación o al menos algunos parámetros críticos en la modulación. El tercer capítulo se dedica a las aplicaciones analógicas. Se describe el concepto de la fotónica de microondas, así como diferentes investigaciones llevadas a cabo en el ámbito analógico para su aplicación en el campo de la fotónica integrada de microondas, todas ellas usando moduladores electro-ópticos de silicio compatibles con los procesos de fabricación CMOS, lo que valida el potencial de la fotónica de silicio como un prometedor enfoque para permitir el desarrollo de aplicaciones de la fotónica integrada de microondas. Por último, las conclusiones sobre el trabajo realizado se proporcionan en el Capítulo 4. / Gutiérrez Campo, AM. (2013). Development of integrated silicon photonics modulation devices for digital and analog applications [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/33330

Robust ion-exchanged glass waveguides exhibit low optical losses in a broad spectral range and they allow integration of several devices on the same chip due to their planar structure. Consequently, they can be a low cost alternative to semiconductors for fabricating various integrated optical devices. Two high performance photonic devices were designed and realized, demonstrating the potential of glass waveguides. The well-controlled silver-film ion-exchange process allowed the fabrication of: i) a highly sensitive biosensor based on optical absorption and, ii) a low loss hybrid electro-optic (EO) polymer modulator with a narrow coplanar electrode gap. The single-mode, channel integrated optical ion-exchange waveguide on borosilicate glass (Corning 0211) is described for broad spectral band (400-650 nm) detection and analysis of heme-containing protein films at a glass/water interface. The evanescent wave interaction is improved significantly by fabricating ion-exchange waveguides with a step-like index profile. Silver nano-particle formation is reduced in order to achieve low loss in the Soret-band (~400 nm). Unlike other surface-specific techniques (e.g. SPR, interferometry) that probe local refractive-index changes and therefore are susceptible to temperature fluctuations, the integrated optical waveguide absorption technique probes molecular-specific transition bands and is expected to be less vulnerable to environmental perturbations. The hybrid integration of phosphate glass (IOG-1) and EO polymer is realized for the first time. The critical alignment steps which are typically required for hybrid optoelectronic devices are eliminated with a simple alignment-free fabrication technique. The low loss adiabatic transition from glass to EO polymer waveguide is enabled by gray scale patterning of the novel EO polymer, AJLY. Total insertion loss of 5 dB and electrode gap of 8 μm is obtained for an optimized device design. EO polymer poling at 135 ºC and 75 V/μm is enabled by the sol-gel buffer layer.

Schizophrenia is a chronic psychotic illness affecting ~21 million people globally. Currently available antipsychotic agents act through a dopamine D2 receptor mechanism, and produce extrapyramidal or metabolic side effects. Hence, there is a need for novel targets and agents. The mGlu2/5-HT2A receptor heteromer has been implicated in the action of antipsychotic agents, and represents a novel and attractive therapeutic target for the treatment of schizophrenia. A long-term goal of this project is to synthesize bivalent ligands where a 5-HT2A receptor antagonist is tethered to an mGlu2 PAM via a linker. The goals of the investigation were to study the SAR of risperidone (an atypical antipsychotic agent) at 5-HT2A receptors using a “deconstruction-reconstruction-elaboration” approach to determine the minimal structural features of risperidone that contribute to its 5-HT2A receptor affinity and antagonism, and to determine where on the “minimized risperidone” structure an mGlu2 PAM can be introduced. Additional goals included studying the binding modes of various mGlu2 PAMs and identifying where on an mGlu2 PAM a risperidone “partial” structure could be introduced. Biological studies of deconstructed/elaborated analogs of risperidone suggest that the entire structure of risperidone is not necessary for 5-HT2A receptor affinity and antagonism, and that a fluoro group contributes to 5-HT2A binding. 6-Fluoro-3-(4-piperidinyl)-1,2-benz[d]isoxazole that has only half the structural features of risperidone retains 5-HT2A receptor affinity and antagonist activity, and represents the “minimized risperidone” structure with the piperidine nitrogen atom representing a potential linker site for eventual construction of bivalent ligands. Molecular modeling studies at 5-HT2A receptors suggest that risperidone and its analogs have more than one binding mode. Modeling studies to evaluate binding modes of various PAMs at mGlu2 receptors, coupled with known SAR information, were used to identify a PAM (JNJ-40411813), and the pyridone nitrogen atom of JNJ-40411813 as a potential linker site. Additionally, potential synthetic routes for JNJ-40411813 were explored that might be of value in the synthesis of bivalent ligands. Based on the structural features of 6-fluoro-3-(4-piperidinyl)-1,2-benz[d]isoxazole, a new pharmacophore for 5-HT2A receptor antagonists, consisting of one aromatic region, a basic protonated amine and hydrogen bond acceptors, has been proposed.

The increasing integration of digital information with our daily lives has led to the rise of big data, cloud computing, and the internet of things. The growth in these categories will lead to an exponential increase in the required capacity for data centers and high performance computation. Meanwhile, due to bottlenecks in data access caused by the limited energy and bandwidth scalability of electrical interconnects, computational speedup can no longer scale with demand. A better solution is necessary in order to increase computational performance and reduce the carbon footprint of our digital future. People have long thought of photonic interconnects, which can offer higher bandwidth, greater energy efficiency, and orders-of-magnitude distance scalability compared to electrical interconnects, as a solution to the data access bottleneck in chip, board, and datacenter scale networks. Over the past three decades we have seen impressive growth of photonic technology from theoretical predictions to high-performance commercially available devices. However, the dream of an all-optical interconnection network for use in CPU, Memory, and rack-to-rack datacenter interconnects is not yet realized. Many challenges and obstacles still have to be addressed. This work investigates these challenges and describe some of the ways to overcome them. First we will first examine the pattern sensitivity of microring modulators, which are likely to be found as the first element in an optical interconnect. My work will illustrate the advantage of using depletion mode modulators compared to injection mode modulators as the number of consecutive symbols in the data pattern increases. Next we will look at the problem of thermal initialization for microring demultiplexers near the output of the optical interconnect. My work demonstrates the fastest achieved initialization speed to-date for a microring based demultiplexer. I will also explore an thermal initialization and control method for microrings based on temperature measurement using a pn-junction. Finally, we will look at how to control and initialize microring and MZI based optical switch fabrics, which is the second element found in a optical interconnect. Work here will show the possibility of switching high-speed WDM datastreams through microring based switches, as well as methods to deal with the complexities inherent in control and initialization of high-radix switch topologies. Through these demonstrations I hope to show that the challenges facing optical interconnects, although very real, are surmountable using reasonable engineering efforts.

Les cancers représentent un problème majeur de santé public d'où la nécessité de rechercher de nouvelles classes de médicaments. Parmi les pistes pour développer de nouveaux traitements, deux ont retenu notre attention et celle de nos collaborateurs : la modulation de l’épissage par des composés comme le NVS-SM2, et l’inhibition de l’oncogène KRAS par des dérivés de produits naturels, les flavaglines. Dans ce contexte, nous avons développé la première synthèse robuste du NVS-SM2, qui peut satisfaire la demande globale de cet agent pour examiner en détail son potentiel thérapeutique dans différents types d’affection. En outre, la stratégie de synthèse rapportée ici pourrait être étendue à de nouveaux analogues de ce composé. D’autre part, nous avons synthétisé de nouvelles flavaglines qui sont en cours d'étude pour leurs effets sur l’inhibition de KRAS. Au cours de cette étude, nous avons découvert de nouvelles réactions, notamment une inversion de configuration d’amines induite par du chlorure de diméthylcarbamoyle. / Cancers represent a major public health problem hence the need to use new classes of medicines. Among the opportunities for developing new treatments, two have caught our attention and that of our collaborators: the modulation of splicing by compounds such as NVS-SM2, and the inhibition of the oncogene KRAS by derivatives of natural products, the flavaglines.In this context, we have developed the first robust synthesis of NVS-SM2, which can satisfy the global demand of this agent to examine in detail its therapeutic potential in different types of disorders. In addition, the synthetic strategy reported here could be extended to new analogues of this compound. Furthermore, we have synthesized new flavaglines that have been examined for their effects on KRAS inhibition. During this study, we discovered new reactions, including a dimethylcarbamoyl chloride-induced amine inversion of configuration.

Ko, Chi Tung. / On t.p. "delta" and "sigma" appear as the Greek letters. / Thesis submitted in: December 2007. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references. / Abstracts in English and Chinese. / Abstract --- p.1 / 摘要 --- p.3 / Acknowledgements --- p.4 / Table of Contents --- p.5 / List of Figures --- p.8 / List of Tables --- p.13 / Chapter Chapter 1 --- Introduction --- p.14 / Chapter 1.1 --- Motivation --- p.14 / Chapter 1.2 --- Objectives --- p.17 / Chapter 1.3 --- Organization of the Thesis --- p.17 / References --- p.18 / Chapter Chapter 2 --- Fundamentals of Delta-sigma Modulators --- p.20 / Chapter 2.1 --- Delta-sigma Modulator as a Feedback System --- p.20 / Chapter 2.2 --- Quantization Noise --- p.22 / Chapter 2.3 --- Oversampling --- p.23 / Chapter 2.4 --- Noise Shaping --- p.25 / Chapter 2.5 --- Performance Parameters --- p.27 / Chapter 2.6 --- Baseband Modulators vs Bandpass Modulators --- p.27 / Chapter 2.7 --- Discrete-time Modulators vs Continuous-time Modulators --- p.28 / Chapter 2.8 --- Single-bit Modulators vs Multi-bit Modulators --- p.29 / Chapter 2.9 --- Non-linearity and Image Problems in Multi-bit Delta-sigma Modulators --- p.29 / Chapter 2.9.1 --- Non-linearity Problem --- p.29 / Chapter 2.9.2 --- Image Problem --- p.31 / Reference --- p.36 / Chapter Chapter 3 --- Image Rejection and Non-linearity Suppression Techniques for Quadrature Multi-bit Δ¡♭ Modulators --- p.38 / Chapter 3.1 --- Quadrature DEM Technique --- p.38 / Chapter 3.1.1 --- Introduction and Working Principle --- p.38 / Chapter 3.1.2 --- Behavioral Simulation Results --- p.42 / Chapter 3.2 --- IQ DWA Technique --- p.44 / Chapter 3.2.1 --- Introduction and Working Principle --- p.44 / Chapter 3.2.2 --- Behavioral Simulation Results --- p.49 / Chapter 3.3 --- DWA and Bit-wise Data-Dependent DEM --- p.52 / Chapter 3.3.1 --- Introduction and Working Principle --- p.52 / Chapter 3.3.2 --- Behavioral Simulation Results --- p.54 / Chapter 3.4 --- Image Rejection Technique for Quadrature Mixer --- p.61 / Chapter 3.5 --- Conclusion --- p.63 / Reference --- p.64 / Chapter Chapter 4 --- System Design of a Multi-Bit CT Modulator for GSM/WCDMA Application --- p.65 / Chapter 4.1 --- Objective of Design and Design Specification --- p.65 / Chapter 4.2 --- Topology Selection --- p.65 / Chapter 4.3 --- Discrete-time Noise Transfer Function Generation --- p.66 / Chapter 4.4 --- Continuous-time Loop Filter Transfer Function Generation --- p.69 / Chapter 4.5 --- Behavioral Model of Modulator --- p.69 / Chapter 4.6 --- Dynamic Range Scaling --- p.75 / Chapter 4.7 --- Behavioral Modeling of Operational Amplifiers --- p.77 / Chapter 4.8 --- Impact of RC Variation on Performance --- p.85 / Chapter 4.9 --- Loop Filter Component Values --- p.88 / Chapter 4.10 --- Summary --- p.90 / Reference --- p.90 / Chapter Chapter 5 --- Transistor-level Implementation of Modulators --- p.92 / Chapter 5.1 --- Overview of Design --- p.92 / Chapter 5.2 --- Design of Operational Transconductance Amplifiers (OTAs) --- p.94 / Chapter 5.2.1 --- First Stage --- p.94 / Chapter 5.2.2 --- Second and Third Stages --- p.98 / Chapter 5.3 --- Design of Feed-forward Transconductance (Gm) Cells --- p.101 / Chapter 5.4 --- Design of Quantizer --- p.102 / Chapter 5.4.1 --- Reference Ladder Design --- p.102 / Chapter 5.4.2 --- Comparator Design --- p.104 / Chapter 5.5 --- Design of Feedback Digital-to-Analog Converter (DAC) --- p.106 / Chapter 5.5.1 --- DWA and DEM Logic --- p.107 / Chapter 5.5.2 --- DAC Circuit --- p.109 / Chapter 5.6 --- Design of Integrated Mixers --- p.111 / Chapter 5.7 --- Design of Clock Generators --- p.112 / Chapter 5.7.1 --- Master Clock Generator --- p.112 / Chapter 5.7.2 --- LO Clock Generator --- p.114 / Chapter 5.7.3 --- Simulation Results --- p.116 / Reference --- p.125 / Chapter Chapter 6 --- Physical Design of Modulators --- p.127 / Chapter 6.1 --- Floor Planning of Modulator --- p.127 / Chapter 6.2 --- Shielding of Sensitive Signals --- p.130 / Chapter 6.3 --- Common Centroid Layout --- p.130 / Chapter 6.4 --- Amplifier Layout --- p.132 / Reference --- p.137 / Chapter Chapter 7 --- Conclusions --- p.138 / Chapter 7.1 --- Conclusions --- p.138 / Chapter 7.2 --- Future Works --- p.138 / Appendix A Schematics of Building Blocks --- p.140 / First Stage Operational Amplifier --- p.140 / First Stage Amplifier Local Bias Circuit --- p.140 / Second and Third Stage Operational Amplifier --- p.141 / Second and Third Stage Local Bias Circuit --- p.141 / CMFB Circuit (First Stage) --- p.142 / CMFB Circuit (Second Stage) --- p.142 / Gm-Feed-forward Cells --- p.143 / Gm Feed-forward Cell Bias Circuit --- p.143 / Reference Ladder Circuit --- p.144 / Pre-amplifier Circuit --- p.145 / Latch Circuit --- p.145 / DAC Circuit (Unit Cell) --- p.146 / Author's Publications --- p.147