Analytical modeling of silicon microring and microdisk modulators with electrical and optical dynamics

We propose an analytical time-domain model for microring and microdisk modulators, which considers both their electrical and optical properties. Theory of the dynamics of microring/microdisk is discussed, and general solutions to the transfer matrix representation are presented. Both static and dynamic predictions from the model are compared to measurement results to demonstrate the accuracy of our model. Static predictions and measurements are presented for power and phase responses, whereas dynamic predictions and measurements are presented for small-signal and large-signal operations. The model verifies that the chirping and modulation bandwidth of the modulators depend on the detuning state. Finally, the accuracy and scalability of several techniques employed in the model are discussed

Silicon photonic modulators and filters for optical interconnects

The goal of this work is to enhance the performance of and demonstrate new applications for silicon photonic modulators and filters. We demonstrate a variety of novel designs and applications of silicon photonic devices for integrated optical interconnects. First, we demonstrate a biasing scheme for travelling-wave Mach-Zehnder modulators in which the bias voltage is applied separately from the data signal. Using this biasing scheme, there is no low frequency cutoff and there is no power consumption in the termination resistor from the bias voltage, which results in an improved modulator having a lower overall power consumption. We experimentally show, as a proof-of-concept, successful high-speed modulation, at a data rate of 28 Gb/s, of a modulator which uses this biasing scheme. Next, we present a novel modulator design in which a microring modulator is placed into each arm of a Mach-Zehnder interferometer. This design uses the sharp phase response of a microring resonator near its resonance so that the light experiences a large phase change when a voltage is applied to the p-n junction phase shifters within the microring. We use temporal coupled mode theory to simulate the time-domain response of this modulator. We then demonstrate a novel modulator design which uses a quarter-wave phase-shifted Bragg grating. The modulator, which was fabricated using 193 nm optical lithography, has open eye diagrams at a data rate of 32 Gb/s. We also show that using a 2³¹-1 pseudorandom binary sequence pattern, the modulator has a bit error rate (BER) less than 10⁻¹² at a data rate of 20 Gb/s and has a BER less than 10⁻¹⁰ at a data rate of 25 Gb/s. Finally, we demonstrate a contra-directional grating coupler-based filter on silicon in an optical add-drop multiplexer configuration and show that it can successfully add and drop a 12.5 Gb/s signal at the same wavelength without substantial signal degradation.Applied Science, Faculty ofElectrical and Computer Engineering, Department ofGraduat

Optical microscope-based spectroscopy of metal nanostructures

A quantum dot is a piece of semiconductor material which has special electronic properties due to the fact that the quantum dot's electron wave function is confined in three dimensions to nanometer scale dimensions which are comparable to the wavelength of the electron's wave function. Optical experiments, which investigate quantum dots, are difficult to develop because of the small size scales encountered, causing low signal-to-noise ratio in measured data. In this project, a LabVIEW control system was developed for an existing Nanopositioner apparatus, which consists of an optical microscope that focuses light on to a sample placed on a stage moving in three dimensions. Coherent forward scattering imaging methods were used to create images of the sample while the stage was moved. The control system locates the center of a region delimited by circular metallic reference markers 100 μm in diameter, where nanoparticles to be scanned were placed using an atomic force microscope. Piezoelectric actuators are used to move the stage with sub micron accuracy in order to image nanoparticles on the order of 50 nm. This control system and apparatus will allow the sponsors to further their research, which ultimately has applications in both optics and quantum information processing. This project was sponsored by Dr. Jeff Young and Dr. Georg Rieger from UBC Physics and Astronomy in the Photonics and Nanostructures Laboratory. The control system and testing to obtain a reasonable scattered light signal from nanoparticles were completed by Lara Backer and Michael Caverley.Science, Faculty ofPhysics and Astronomy, Department ofUnreviewedUndergraduat

International Harmonization of Nomenclature and Diagnostic Criteria (INHAND): Nonproliferative and Proliferative Lesions of the Dog

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions) Project (www.toxpath.org/inhand.asp) is a joint initiative of the societies of toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying lesions observed in most tissues and organs from the dog used in nonclinical safety studies. Some of the lesions are illustrated by color photomicrographs. The standardized nomenclature presented in this document is also available electronically on the internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous lesions, lesions induced by exposure to test materials, and relevant infectious and parasitic lesions. A widely accepted and utilized international harmonization of nomenclature for lesions in laboratory animals will provide a common language among regulatory and scientific research organizations in different countries and increase and enrich international exchanges of information among toxicologists and pathologists

A visão brasileira da futura ordem global Brazil's vision of the future global order

Este artigo visa desdobrar a concepção brasileira da futura ordem global localizada entre os polos extremos de um concerto de grandes potências e de uma ordem mundial multirregional. O autor demonstra como os formuladores de política externa brasileira contribuem para um tipo de ordem global que oferece espaço de manobra para a potência emergente. As opções de política externa do Brasil são limitadas, diante do superior poder material (hard power) das grandes potências estabelecidas. A estratégia de soft balancing do Brasil envolve estratégias institucionais, como a formação de coalizões diplomáticas limitadas ou alianças para restringir o poder das grandes potências estabelecidas. O Brasil tem estado entre os mais poderosos condutores de mudança incremental na diplomacia mundial e é beneficiado em grande parte pelas conectadas mudanças de poder global. Em uma ordem global moldada por grandes potências por meio de arranjos e instituições internacionais, esses jogadores que efetivamente operam em ambos como inovadores, construtores de coalizões e porta-vozes, ao mesmo tempo em que preservam grande parcela de soberania e autonomia, têm o potencial de influenciar substancialmente os resultados da futura política global.<br>This article aims to unfold the Brazilian conception of the future global order located between the extreme poles of a concert of great powers and a multiregional world order. The author demonstrates how Brazilian foreign policy makers contribute to the kind of global order, which offers most room to manoeuvre to the rising power. The foreign policy options of Brazil are limited in view of the superior hard power of the established great powers. Brazil's soft balancing strategy involves institutional strategies such as the formation of limited diplomatic coalitions or ententes to constrain the power of the established great powers. Brazil has been amongst the most powerful drivers of incremental change in world diplomacy and it benefits most from the connected global power shifts. In a global order shaped by great powers through international groupings and institutions, those players who effectively operate within them as innovators, coalition builders and spokesmen while preserving great amounts of sovereignty and autonomy have the potential to substantially influence the outcomes of future global politics