Chiral Quantum Optics using Topological Photonics

Topological photonics has opened new avenues to designing photonic devices along with opening a plethora of applications. Recently, even though there have been many interesting studies in topological photonics in the classical domain, the quantum regime has remained largely unexplored. In this thesis, I will demonstrate a recently developed topological photonic crystal structure for interfacing a single quantum dot spin with a photon to realize light-matter interaction with topolog-ical photonic states. Developed on a thin slab of Gallium Arsenide(GaAs) mem- brane with electron beam lithography, such a device supports two robust counter- propagating edge states at the boundary of two distinct topological photonic crystals at near-IR wavelength. I will show the chiral coupling of circularly polarized lights emitted from a single Indium Arsenide(InAs) quantum dot under a strong magnetic field into these topological edge modes. Owing to the topological nature of these guided modes, I will demonstrate this photon routing to be robust against sharp corners along the waveguide. Additionally, taking it further into the cavity-QED regime, we will build a topological photonic crystal resonator. This new type of resonator will be based on valley-Hall topological physics and sustain two counter- propagating resonator modes. Thanks to the robustness of the topological edge modes to sharp bends, the newly formed resonators can take various shapes, the simplest one being a triangular optical resonator. We will study the chiral coupling of such resonator modes with a single quantum dot emission. Moreover, we will show an intensity enhancement of a single dot emission when it resonantly couples with a cavity mode. This new topological photonic crystal platform paves paths for fault-tolerant complex photonic circuits, secure quantum computation, and explor- ing unconventional quantum states of light and chiral spin networks

Nanofabrication

We face many challenges in the 21st century, such as sustainably meeting the world's growing demand for energy and consumer goods. I believe that new developments in science and technology will help solve many of these problems. Nanofabrication is one of the keys to the development of novel materials, devices and systems. Precise control of nanomaterials, nanostructures, nanodevices and their performances is essential for future innovations in technology. The book "Nanofabrication" provides the latest research developments in nanofabrication of organic and inorganic materials, biomaterials and hybrid materials. I hope that "Nanofabrication" will contribute to creating a brighter future for the next generation

New frequency reconfigurable antennas for wide frequency range tuning

Frequency reconfigurable antennas are becoming a compelling solution for the increasing demand of higher antenna capabilities, since they can operate at tunable narrow frequency bands while rejecting the undesirable signals from other bands. The aim of this project is to develop new designs for frequency reconfigurable antennas that can work across a wide frequency range (from 1 GHz up to 6 GHz) while maintaining stable radiation pattern and polarisation as required by the industry sponsors. A Vivaldi antenna is considered as the basis for a frequency reconfigurable design as it maintains the radiation characteristics in its operating band. Dual-band, tri-band and quad-band switched reconfigurable designs are proposed and analysed. These antennas are electronically-tuned using RF switches which adjust the impedance to reconfigure the operating band of the antenna. A prototype is tested in an anechoic chamber obtaining good performance. However, as the switches lead to several challenges, such as the effect of bias lines and the excessive insertion losses, a new approach is taken. State-of-the-art technologies are studied and fluid antennas are introduced. Current developments show that liquid antennas can have radiation efficiencies up to 90 % and conductivities close to copper, which makes them a good candidate to fulfil the requirements of this project. A hybrid Vivaldi antenna with an ionised water switch is proposed and a prototype tested. By introducing ionised water into a specific point of the feed line the operating frequency of the antenna is adjusted. The replacement of RF switches for electronically-controlled fluids brings high flexibility, suppression of the bias lines impact, dynamic adjustment and continuous frequency tuning compared to conventional antenna systems

Active Tuning of LSPR and SLR for Au Nanoring Metasurfaces and Hybrids via Flexible Plasmonics

Recent advances in nanofabrication have stimulated research efforts in the field of flexible plasmonics by integrating functional metasurfaces onto mechanically flexible substrates. In this thesis, we report on the fabrication of flexible metasurfaces composed of gold regular and elliptical nanoring arrays embedded in polydimethylsiloxane (PDMS), using state-of-the-art electron beam lithography and wet-etching transfer techniques. In-situ dark-field reflection spectra are monitored on the flexible systems by implementing a homemade micro-stretcher inside the spectroscope. The feasibility of pattern transfer and reliability of optical measurement are further confirmed by subsequent SEM characterizations on PDMS. The spectral behavior of thin-width nanoring square arrays exhibits a significant shift towards longer wavelengths due to in-situ shape changes under strain. The shape-altering ability is carefully demonstrated through optical/SEM measurements and numerical simulations, which is further understood by a purposed squeezing mechanism. On the other hand, the spectral evolution of elliptical nanorings in square and triangular arrays presents interesting polarization dependence and spectral blueshift under strain. The square array subjected to high strain values exhibits also surface lattice resonances with Fano features due to the coupling between the grating and plasmonic modes. Additionally, we demonstrate Fano resonances in ring-disc-pair hybrid systems on a rigid substrate. The ring-disc-pair system shows significantly enhanced Fano features and surface-enhanced Raman signals with a decreasing gap, predicting well an active spectral tuning once they are transferred onto flexible substrates in future work. In general, this thesis expands the possibilities of conventional gap-altering flexible plasmonics by investigating plasmonic spectral shifts corresponding to NPs shape-altering, surface lattice resonances, and Fano coupling under strain. It provides valuable insights into strain sensing, flexible color displays, and wearable electronics with high sensitivity and selectivity

Piezoelectric Materials

The science and technology in the area of piezoelectric ceramics are extremely progressing, especially the materials research, measurement technique, theory and applications, and furthermore, demanded to fit social technical requests such as environmental problems. While they had been concentrated on piezoelectric ceramics composed of lead-containing compositions, such as lead zirconate titanate (PZT) and lead titanate, at the beginning because of the high piezoelectricity, recently lead water pollution by soluble PZT of our environment must be considered. Therefore, different new compositions of lead-free ceramics in order to replace PZT are needed. Until now, there have been many studies on lead-free ceramics looking for new morphotropic phase boundaries, ceramic microstructure control to realize high ceramic density, including composites and texture developments, and applications to new evaluation techniques to search for high piezoelectricity. The purpose of this book is focused on the latest reports in piezoelectric materials such as lead-free ceramics, single crystals, and thin films from viewpoints of piezoelectric materials, piezoelectric science, and piezoelectric applications

Advanced Electromagnetic Waves

This book endeavors to give the reader a strong base in the advanced theory of electromagnetic waves and its applications, while keeping pace with research in various other disciplines that apply electrostatics/electrodynamics theory. The treatment is highly mathematical, which tends to obscure the principles involved

Functional dielectrics in-depth study

Навчальний посібник присвячено фізичним основам та практичному застосуванню в електроніці багатофункціональних діелектриків. Дається коротка історія основних стадій розвитку електроніки та фізичні основи сучасного електронного матеріалознавства. Представлені сучасні уявлення про фізичні механізми функціональності методом порівняння усталених концепцій і нових ідей: для демонстрації динаміки розвитку деяких напрямів функціональної електроніки дискусійнсіоні теорії порівнюються з класичними уявленнями. Використовуються сучасні дослідження мікроелектроніки та нанофізики, демонструється зв'язок внутрішньої структури та фізичних властивостей матеріалів. Навчальний посібник заснований на багаторічному досвіді авторів у викладанні курсу фізичного матеріалознавства, призначеного для студентів вищих навчальних закладів зі спеціалізацією 105 "Прикладна фізика та наноматерили". Книга може бути рекомендована аспірантам та дослідникам, що спеціалізуються в галузі матеріалознавства.The textbook discusses new developments, some methods for calculating parameters and practical application of functional dielectrics. Modern theoretical concepts, new experimental data main specifications of basic materials are considered. Provides basic data on the history of electronics, as well as the basic information about the materials used in electronics is given. The focus is on explaining the physical mechanisms of many effects used in modern electronics. The textbook is based on the authors' many years of experience in teaching physical materials science, intended for the students of higher educational institutions with specializations in the fields of "Applied Physics" and "Microelectronics and nanoelectronics". The book can also be used by the graduate students, engineers and researchers specializing in the materials science