Manipulating Electromagnetic Fields with Advanced Metamaterials

In almost any scientific experiment, we take into account some particular properties of materials, e.g. electromagnetic, mechanical, thermal, etc. These properties determine a majority of the physical phenomena that arise from the interaction with matter, and thus restrict potential applications of natural materials. The discovery and subsequent development of novel materials regularly boost the standards of living through new technological progress and cutting-edge research. One of the very recent and promising discoveries is related to the field of metamaterials - artificially structured media with subwavelength patterning. These artificial materials offer a unique platform with large flexibility and unusual properties for tailoring acoustic and electromagnetic waves, including novel ways for the manipulation of light. In this thesis, I employed the concept of metamaterials for both the study of new physical phenomena related to the emerging field of topological photonics and also develop innovative applications of specific metamaterials for the advancing the magnetic resonance imaging (MRI) machines. Chapter 1 provides an introduction to the field of metamaterials and their unusual properties, starting from the definition of meta-atoms and expanding to more complex structures, including one-dimensional meta-chains and metasurfaces. This is followed by an introduction to the fields of topological photonics and magnetic resonance imaging techniques. The experimental approaches based on a microwave platform are also described. Finally, the thesis motivation and structure are summarized. Chapter 2 presents experimental studies of topological features of zigzag arrays of dielectric particles. It includes the first experimental observation of the subwavelength photonic topological edge states, topological phase transition in the chains of dielectric particles, as well as, the study of the specific features of the photonic spin Hall effect mediated by the excitation of the subwavelength topological edge states. Chapter 3 describes the study of bianisotropic metasurfaces and metamaterials. The experimental designs of bianisotropic metallic and dielectric metasurfaces are presented, with a direct observation of topologically nontrivial edge states. Further, it is revealed how to couple topologically protected metasurfaces to form three-dimensional all-dielectric topologically nontrivial bianisotropic metamaterials and metacrystals. Chapter 4 focuses on the study metasurfaces based on resonant arrays of metallic wires used for advancing magnetic resonance imaging (MRI) characteristics. A new conceptual idea for the substantial enhancement of signal-to-noise ratio of a 1.5T MRI is presented. This approach is further developed and extended to ultra-high field MRI (7T) where a direct evaluation of the metasurface properties is examined during in-vivo human brain imaging. Chapter 5 summarizes the results and concludes the thesis

Selected problems of materials science. Vol. 2. Nano-dielectrics metals in electronics. Mеtamaterials. Multiferroics. Nano-magnetics

The textbook examines physical foundations and practical application of current electronics materials. Modern theories are presented, more important experimental data and specifications of basic materials necessary for practical application are given. Contemporary research in the field of microelectronics and nanophysics is taken into account, while special attention is paid to the influence of the internal structure on the physical properties of materials and the prospects for their use. English-language lectures and other classes on the subject of the book are held at Igor Sikorsky Kyiv Polytechnic Institute at the departments of “Applied Physics” and “Microelectronics” on the subject of materials science, which is necessary for students of higher educational institutions when performing scientific works. For master’s degree applicants in specialty 105 “Applied physics and nanomaterials”.Розглянуто фізичні основи та практичне застосування актуальних матеріалів електроніки. Подано сучасні теорії, наведено найважливіші експериментальні дані та специфікації основних матеріалів, які потрібні для практичного застосування. Враховано сучасні дослідження у галузі мікроелектроніки та нанофізики, при цьому особливу увагу приділено впливу внутрішньої структури на фізичні властивості матеріалів і на перспективи їх використання. Англомовні лекції та інші види занять за тематикою книги проводяться в КПІ ім. Ігоря Сікорського на кафедрах «Прикладна фізика» та «Мікро-електроніка» за напрямом матеріалознавство, що необхідно студентам вищих навчальних закладів при виконанні наукових робіт. Для здобувачів магістратури за спеціальністю 105 «Прикладна фізика та наноматеріали»

Enabling Real-Time Terahertz Imaging With Advanced Optics and Computational Imaging

La bande des térahertz est une région particulière du spectre électromagnétique comprenant les fréquences entre 0.1 THz à 10 THz, pour des longueurs d’onde respectives de 3 mm à 30 um. Malgré tout l’intérêt que cette région a suscité au cours de la dernière décennie, de grands obstacles demeurent pour une application plus généralisée de la radiation THz dans les applications d’imagerie. Cette thèse aborde le problème du temps d’acquisition d’une image THz. Notre objectif principal sera de développer des technologies et techniques pour permettre l’imagerie THz en temps réel. Nous débutons cette thèse avec une revue de littérature approfondie sur le sujet de l’imagerie THz en temps réel. Cette revue commence par énumérer plusieurs sources et détecteurs THz qui peuvent immédiatement être utilisés en imagerie THz. Nous détaillons par la suite plusieurs modalités d’imagerie développés au cours des dernières années : 1) Imagerie THz en transmission, en réflexion et de conductivité, 2) imagerie THz pulsée, 3) imagerie THz par tomographie computationnelle et 4) imagerie THz en champ proche. Nous discutons par la suite plus en détail à propos de technologies habilitantes pour l’imagerie THz en temps réel. Pour cela, nous couvrons trois différents axes de recherche développés en littérature : 1)Imagerie en temps réel de spectroscopie THz dans le domaine du temps, 2) caméras THz et 3) imagerie en temps réel avec détecteur à pixel unique. Nous présentons ensuite le système d’imagerie que nous avons développé pour les démonstrations expérimentales de cette thèse. Ce système est basé sur la spectroscopie THz en temps réel et permet donc d’obtenir des images hyperspectrales en amplitude et en phase. Il utilise des antennes photoconductrices pour l’émission et la détection de la radiation THz. En outre, le détecteur est fibré, ce qui permet de le déplacer spatialement pour construire des images. Nous couvrons aussi brièvement plusieurs techniques de fabrication avancées que nous avons utilisées : impression 3D par filament, stéréolithographie, machinage CNC, gravure/découpe laser et transfert de métal par toner. Nous portons ensuite notre attention à l’objectif principal de cette thèse à travers trois démonstrations distinctes. Premièrement, nous concevons des composants THz à faibles pertes en utilisant des matériaux poreux. L’absence de détecteurs THz ultra-sensibles implique que les pertes encourues dans un système d’imagerie sont hautement indésirables. En effet, un moyennage temporel est généralement fait pour extraire de faibles signaux THz sévèrement enfouis sous le bruit technique. Ceci a pour impact de diminuer le nombre d’images à la seconde. ----------Abstract The terahertz band is a region of the electromagnetic spectrum comprising frequencies between 0.1 THz to 10 THz for respective wavelengths of 3 mm to 30 um. Despite all the interest and potential generated in the past decade for applications of this spectral band, there are still major hurdles impeding a wider use of THz radiation for imaging. This thesis addresses the problem of image acquisition time. Our main objective is to develop technologies and techniques to achieve real-time THz imaging. We start this thesis with a comprehensive review of the scientific literature on the topic of realtime THz imaging. This review begins by listing some off-the-shelf THz sources and detectors that could be readily used in THz imaging. We then detail some key imaging modalities developed in the past years: 1) THz transmission, reflection and conductivity imaging, 2) THz pulsed imaging, 3) THz computed tomography, and 4) THz near-field imaging. We then discuss practical enabling technologies for real-time THz imaging: 1) Real-time THz timedomain spectroscopy imaging, 2) THz cameras, and 3) real-time THz single-pixel imaging. We then present our fiber-coupled THz time-domain spectroscopy imaging setup. This system is used throughout the thesis for experimental demonstrations. We also briefly overview many advanced fabrication techniques that we have used, namely fused deposition modeling,stereolithography, CNC machining, laser cutting/engraving and metal transfer using toner. We then turn to the main objective of this thesis with three distinct demonstrations. First, we design low-loss THz components using porous media. The losses incurred in the imaging system are highly undesirable due to the lack of sensitive THz detectors. Indeed, time averaging is generally performed in order to retrieve THz signals severely buried under noise,which in return reduce the framerate. We propose to use low-refractive index subwavelength inclusions (air holes) in a solid dielectric material to build optical components. We show that these components have smaller losses than their all-solid counterparts with otherwise identical properties. We fabricate a planar porous lens and an orbital angular momentum phase plate, and we use our imaging system to characterize their effects on the THz beam. Second, we demonstrate a spectral encoding technique to significantly reduce the required number of measurements to reconstruct a THz image in a single-pixel detection scheme

Advanced Radio Frequency Antennas for Modern Communication and Medical Systems

The main objective of this book is to present novel radio frequency (RF) antennas for 5G, IOT, and medical applications. The book is divided into four sections that present the main topics of radio frequency antennas. The rapid growth in development of cellular wireless communication systems over the last twenty years has resulted in most of world population owning smartphones, smart watches, I-pads, and other RF communication devices. Efficient compact wideband antennas are crucial in RF communication devices. This book presents information on planar antennas, cavity antennas, Vivaldi antennas, phased arrays, MIMO antennas, beamforming phased array reconfigurable Pabry-Perot cavity antennas, and time modulated linear array

A hybrid piezoelectric and electrostatic energy harvester for scavenging arterial pulsations

Implantable and wearable biomedical devices suffer from a limited lifespan of on-board batteries which results in a requirement to change the battery or the device itself causing additional physical discomfort. In order to overcome this, various energy harvesters have been developed. The human body possesses several types of energy available for scavenging through appropriately designed energy harvesting devices, while cardiovascular system in particular represents a constant reliable source of mechanical energy from vibration. Most conventional energy harvesters exploit only a single phenomenon, such piezo- or triboelectricity, thus producing reduced power density. As an improvement, hybridisation of energy harvesters intends to negate this drawback by simultaneously scavenging energy by multiple harvesters. In the present work, the reverse electrowetting on dielectric (REWOD) phenomenon is combined with the piezoelectric effect in a proof-of-concept hybrid harvester for scavenging biomechanical energy from arterial or other type pulsations. A mathematical model of the harvester was developed, and a computational investigation using CFD, and fluid-structure interaction simulations were carried out using the COMSOL Multiphysics software. The effect of the materials of piezoelectric film and geometrical features of the harvester on parameters such as the displacement, the frequency of pulsations and the energy produced were studied. An experimental setup that could imitate the displacements caused from arterial pulsations was designed and the produced electrical energy characteristics were analysed. A comparison between experimental and computational data was carried out and demonstrated a good agreement. Dependencies between geometrical parameters and electrical output were obtained, recommendation on piezoelectric materials and design solutions were provided

Proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress

Published proceedings of the 2018 Canadian Society for Mechanical Engineering (CSME) International Congress, hosted by York University, 27-30 May 2018