Active and Fast Tunable Plasmonic Metamaterials

Active and Fast Tunable Plasmonic Metamaterials is a research development that has contributed to studying the interaction between light and matter, specifically focusing on the interaction between the electromagnetic field and free electrons in metals. This interaction can be stimulated by the electric component of light, leading to collective oscillations. In the field of nanotechnology, these phenomena have garnered significant interest due to their ability to enable the transmission of both optical signals and electric currents through the same thin metal structure. This presents an opportunity to connect the combined advantages of photonics and electronics within a single platform. This innovation gives rise to a new subfield of photonics known as plasmonic metamaterials.Plasmonic metamaterials are artificial engineering materials whose optical properties can be engineered to generate the desired response to an incident electromagnetic wave. They consist of subwavelength-scale structures which can be understood as the atoms in conventional materials. The collective response of a randomly or periodically ordered ensemble of such meta-atoms defines the properties of the metamaterials, which can be described in terms of parameters such as permittivity, permeability, refractive index, and impedance. At the interface between noble metal particles and dielectric media, collective oscillations of the free electrons in the metal particles can be resonantly excited, known as plasmon resonances. This work considered two plasmon resonances: localised surface plasmon resonances (LSPRs) and propagating surface plasmon polaritons (SPPs).The investigated plasmonic metamaterials, designed with specific structures, were considered for use in various applications, including telecommunications, information processing, sensing, industry, lighting, photovoltaic, metrology, and healthcare. The sample structures are manufactured using metal and dielectric materials as artificial composite materials. It can be used in the electromagnetic spectrum's visible and near-infrared wavelength range. Results obtained proved that artificial composite material can produce a thermal coherent emission at the mid-infrared wavelength range and enable active and fast-tunable optoelectronic devices. Therefore, this work focused on the integrated thermal infrared light source platforms for various applications such as thermal analysis, imaging, security, biosensing, and medical diagnosis. Enabled by Kirchhoff's law of thermal radiation, this work combined the concepts of material absorption with material emission. Hence, the results obtained proved that this approach enhances the overall performance of the active and fast-tunable plasmonic metamaterial in terms of with effortless and fast tunability. This work further considers the narrow line width of the coherent thermal emission, tunable emission, and angular tunable emission at the mid-infrared, which are achieved through plasmonic stacked grating structure (PSGs) and plasmonic infrared absorber structure (PIRAs).Three-dimensional (3D) plasmonic stacked gratings (PSGs) was used to create a tunable plasmonic metamaterial at optical wavelengths ranging from 3 m to 6 m, and from 6m to 9 m. These PSGs are made of a metallic grating with corrugations caused by narrow air openings, followed by a Bragg grating (BG). Additionally, this work demonstrated a thermal radiation source customised for the mid-infrared wavelength range of 3 μm to 5 μm. This source exhibits intriguing characteristics such as high emissivity, narrowband spectra, and sharp angular response capabilities. The proposed thermal emitter consists of a two-dimensional (2D) metallic grating on top of a one-dimensional dielectric BG.Results obtained presented a plasmonic infrared absorber (PIRA) graphene nanostructure designed for a wavelength range of 3 to 14 μm. It was observed and concluded that this wavelength range offers excellent opportunities for detection, especially when targeting gas molecules in the infrared atmospheric windows. The design framework is based on active plasmon control for subwavelength-scale infrared absorbers within the mid-infrared range of the electromagnetic spectrum. Furthermore, this design is useful for applications such as infrared microbolometers, infrared photodetectors, and photovoltaic cells.Finally, the observation and conclusion drawn for the sample of nanostructure used in this work, which consists of an artificial composite arrangement with plasmonic material, can contribute to a highly efficient mid-infrared light source with low power consumption, fast response emissions, and is a cost-effective structure

Polymer Composites for Electrical and Electronic Engineering Application

Polymer composite materials have attracted great interest for the development of electrical and electronic engineering and technology, and have been widely applied in electrical power systems, electrical insulation equipment, electrical and electronic devices, etc. Due to the significant expansion in the use of newly developed polymer composite materials, it is necessary to understand and accurately describe the relationship between composite structure and material properties, as only based on thorough laboratory characterization is it possible to estimate the properties for their future commercial applications. This book focuses on polymer composites applied in the field of electrical and electronic equipment, including but not limited to synthesis and preparation of new polymeric materials, structure–properties relationship of polymer composites, evaluation of materials application, simulation and modelling of material performance

Radiative Heat Transfer with Nanowire/Nanohole Metamaterials for Thermal Energy Harvesting Applications

abstract: Recently, nanostructured metamaterials have attracted lots of attentions due to its tunable artificial properties. In particular, nanowire/nanohole based metamaterials which are known of the capability of large area fabrication were intensively studied. Most of the studies are only based on the electrical responses of the metamaterials; however, magnetic response, is usually neglected since magnetic material does not exist naturally within the visible or infrared range. For the past few years, artificial magnetic response from nanostructure based metamaterials has been proposed. This reveals the possibility of exciting resonance modes based on magnetic responses in nanowire/nanohole metamaterials which can potentially provide additional enhancement on radiative transport. On the other hand, beyond classical far-field radiative heat transfer, near-field radiation which is known of exceeding the Planck’s blackbody limit has also become a hot topic in the field. This PhD dissertation aims to obtain a deep fundamental understanding of nanowire/nanohole based metamaterials in both far-field and near-field in terms of both electrical and magnetic responses. The underlying mechanisms that can be excited by nanowire/nanohole metamaterials such as electrical surface plasmon polariton, magnetic hyperbolic mode, magnetic polariton, etc., will be theoretically studied in both far-field and near-field. Furthermore, other than conventional effective medium theory which only considers the electrical response of metamaterials, the artificial magnetic response of metamaterials will also be studied through parameter retrieval of far-field optical and radiative properties for studying near-field radiative transport. Moreover, a custom-made AFM tip based metrology will be employed to experimentally study near-field radiative transfer between a plate and a sphere separated by nanometer vacuum gaps in vacuum. This transformative research will break new ground in nanoscale radiative heat transfer for various applications in energy systems, thermal management, and thermal imaging and sensing.Dissertation/ThesisDoctoral Dissertation Mechanical Engineering 201

Nanoplasmonics In Two-dimensional Dirac and Three-dimensional Metallic Nanostructure Systems

Surface plasmons are collective oscillation of electrons which are coupled to the incident electric field. Excitation of surface plasmon is a route to engineer the behavior of light in nanometer length scale and amplifying the light-matter interaction. This interaction is an outcome of near-field enhancement close to the metal surface which leads to plasmon damping through radiative decay to outgoing photons and nonradiative decay inside and on the surface of the material to create an electron-hole pair via interband or intraband Landau damping. Plasmonics in Dirac systems such as graphene show novel features due to massless electrons and holes around the Dirac cones. Linear band structure of Dirac materials in the low-momentum limit gives rise to the unprecedented optical and electrical properties. Electronical tunability of the plasmon resonance frequency through applying a gate voltage, highly confined electric field, and low plasmon damping are the other special propoerties of the Dirac plasmons. In this work, I will summarize the theoretical and experimental aspects of the electrostatical tunable systems made from monolayer graphene working in mid-infrared regime. I will demonstrate how a cavity-coupled nanopatterned graphene excites Dirac plasmons and enhances the light-matter interaction. The resonance frequency of the Dirac plasmons is tunable by applying a gate voltage. I will show how different gate-dielectrics, and the external conditions like the polarization and angle of incident light affect on the optical response of the nanostructure systems. I will then show the application of these nanodevices in infrared detection at room temperature by using plasmon-assisted hot carriers generation. An asymmetric nanopatterned graphene shows a high responsivity at room temperature which is unprecedented. At the end, I will demonstrate the properties of surface plasmons on 3D noble metals and its applications in light-funneling, photodetection, and light-focusing

Metamaterial

In-depth analysis of the theory, properties and description of the most potential technological applications of metamaterials for the realization of novel devices such as subwavelength lenses, invisibility cloaks, dipole and reflector antennas, high frequency telecommunications, new designs of bandpass filters, absorbers and concentrators of EM waves etc. In order to create a new devices it is necessary to know the main electrodynamical characteristics of metamaterial structures on the basis of which the device is supposed to be created. The electromagnetic wave scattering surfaces built with metamaterials are primarily based on the ability of metamaterials to control the surrounded electromagnetic fields by varying their permeability and permittivity characteristics. The book covers some solutions for microwave wavelength scales as well as exploitation of nanoscale EM wavelength such as visible specter using recent advances of nanotechnology, for instance in the field of nanowires, nanopolymers, carbon nanotubes and graphene. Metamaterial is suitable for scholars from extremely large scientific domain and therefore given to engineers, scientists, graduates and other interested professionals from photonics to nanoscience and from material science to antenna engineering as a comprehensive reference on this artificial materials of tomorrow

Phase Shaping In The Infrared By Planar Quasi-periodic Surfaces Comprised Of Sub-wavelength Elements

Reflectarrays are passive quasi-periodic sub-wavelength antenna arrays designed for discrete reflected phase manipulation at each individual antenna element making up the array. By spatially varying the phase response of the antenna array, reflectarrays allow a planar surface to impress a non-planar phasefront upon re-radiation. Such devices have become commonplace at radio frequencies. In this dissertation, they are demonstrated in the infrared for the first time--at frequencies as high as 194 THz. Relevant aspects of computational electromagnetic modeling are explored, to yield design procedures optimized for these high frequencies. Modeling is also utilized to demonstrate the phase response of a generalized metallic patch resonator in terms of its dependence on element dimensions, surrounding materials, angle of incidence, and frequency. The impact of realistic dispersion of the real and imaginary parts of the metallic permittivity on the magnitude and bandwidth of the resonance behavior is thoroughly investigated. Several single-phase reflectarrays are fabricated and measurement techniques are developed for evaluating these surfaces. In all of these cases, there is excellent agreement between the computational model results and the measured device characteristics. With accurate modeling and measurement, it is possible to proceed to explore some specific device architectures appropriate for focusing reflectarrays, including binary-phase and phase-incremental approaches. Image quality aspects of these focusing reflectarrays are considered from geometrical and chromatic-aberration perspectives. The dissertation concludes by briefly considering two additional analogous devices--the transmitarray for tailoring transmissive phase response, and the emitarray for angular control of thermally emitted radiation

Utilizing equivalent circuits to describe the strain- and temperature-dependence of electromagnetic metamaterials

Electromagnetic metamaterials have demonstrated unique and unprecedented behaviors in a laboratory setting. They achieve these novel properties by utilizing geometry and structure, as opposed to a strict reliance on chemical composition, to dictate their interactions with electromagnetic (EM) radiation. As such, metamaterials significantly expand the toolkit from which engineers can draw when designing devices that interact with EM waves. However, the flexibility afforded by these structures also implies environmental sensitivities not seen in traditional material systems. Some recent efforts have borne this out, demonstrating significant strain- and temperature-dependence in metamaterial samples. To date, little has been done to fundamentally understand the mechanisms driving these dependencies. This understanding is crucial for developing engineering-quality predictions of the EM performance of metamaterial structures in a relevant environment, a crucial step in transitioning this technology from laboratory novelty to fielded capability. This study leverages equivalent circuit models to understand and predict the strain- and temperature-dependent EM properties of metamaterial structures. Straightforward analytic expressions for the equivalent circuit parameters (resistance, inductance, capacitance) detail the strain-induced changes in geometry as well as the temperature-dependence of the metamaterials constituent materials. These expressions are initially utilized to predict the strain-dependent shift in resonant frequency, a key descriptor of the metamaterial\u27s EM behavior. These same expressions are then utilized to describe the metamaterial\u27s strain- and temperature-dependent EM constitutive properties (permittivity, ε, and permeability, μ), which are critical for solving Maxwell\u27s equations and performing EM simulations within the material. This study focused on the Electric-LC (ELC) resonator, a design commonly used to provide a tailored response to the electric field of the EM wave. However, the author believes that the same process, and similar analytic expressions for the circuit parameters and constitutive properties, could be used to successfully predict the strain- and temperature-dependence of other metamaterial structures, to include Split-Ring-Resonators (SRRs), a design commonly used to provide a tailored magnetic response to EM waves.\u2

Micro-electro-opto-fluidic systems for biomedical drug screening and electromagnetic filtering and cloaking applications

Microfluidic is a multidisciplinary field that deals with the flow of liquid inside micro-meter size channels. In order to be considered as microfluidics, at least one dimension of the channel should be in the range of one micrometer or sub-millimeter. Microfluidic technology includes designing, manufacturing, formulating devices and processing the liquid. As numerous bio-science and engineering techniques have utilized microfluidics and highly integrated with this remarkable technology, the microfluidic platform technology has extended to several sub-techs: micro-scale analysis, soft-lithography fabrication, polymer science and processing, on-chip sensing and micro-scale fluid manipulation. Those sub-techs have been developed rapidly along with the booming microfluidics. The advance of those techniques has promoted microfluidic system diverse and widespread applications. Some examples that employ this technology include on-chip drug screening, micro-scale analysis, flexible electronics, biochemical assays. Many engineering field, such as optics, electronics, chemicals and electromagnetics, have been integrated with the microfluidic system to form a completed system for sensing, analyzing or realizing some specific applications. Through the fusion of those technologies with microfluidics, many emerging technologies are well initiated, such as optofluidics and electrofluidics. Despite of rapid advancement of each parent technology field, those intersected technologies are still in their infancy and many technological elements and even some fundamental concepts are just now being developed. Thus, it provides great opportunity to explore more about those emerging technologies. Some particular areas that mainly interest researchers including cost deduction, effective fabrication, highly integration, portability and applicability. Due to the wide and diversity nature of the microfluidic technology and numerous combinations from the integration with other fields, it is very difficult to choose a single aspect or particular subject to research. Hence, we would like to focus on the application orientated microfluidic techniques that integrated with other engineering areas, in particular optics and electronics. Correspondingly, I will present four microfluidic platforms that integrated with optics, electronics for different application purpose. First of all, fiber-optics was integrated into a microfluidic device to detect muscular force generation of microscopic nematodes. The integrated opto-fluidic device is capable of measuring the muscular force of nematode worms normal to the translational movement direction with high sensitivity, high data reliability, and simple device structure. The ability to quantify the muscular forces of small nematode worms will provide a new approach for screening mutants at single animal resolution. Secondly, electronic grids were integrated into a microfluidic chip to realize on-chip tracking of nematode locomotion. The micro-electro-fluidic approach is capable of real-time lens-less and image-sensor-less monitoring of the locomotion of microscopic nematodes. The technology showed promise for overcoming the constraint of the limited field of view of conventional optical microscopy, with relatively low cost, good spatial resolution, and high portability. Thirdly, electromagnetic spit ring resonator (SRR) structure was adopted as microfluidic channel filled with liquid metal to fabricate a tunable microfluidic microwave electronics called meta-atom. The presented meta-atom is capable of tuning its electromagnetic (EM) response characteristics over a broad frequency range via simple mechanical stretching. The meta-atom in this study presents a simple but effective building block for realizing mechanically tunable metamaterials. Finally, based on the meta-atom we previously developed, an array of electromagnetic SRR shaped microfluidic channels filled with liquid metal to form a flexible metamaterial-based microwave electronic “skin” or meta-skin. When stretched, the meta-skin performs as a tunable frequency selective surface with a wide resonance frequency tuning range. When wrapped around a curved dielectric material, the meta-skin functions as a flexible “cloaking” surface to significantly suppress scattering from the surface of the dielectric material along different directions. The microfluidic platform will find great applications when it integrates with other technologies. The development of such integration will greatly intersect different research areas and benefit all of the intersected technologies and fields, thus broadening the future applications

Terahertz Technology for Defense and Security-Related Applications

This thesis deals with chosen aspects of terahertz (THz) technology that have potential in defense and security-related applications. A novel method for simultaneous data acquisition in time-resolved THz spectroscopy experiments is developed. This technique is demonstrated by extracting the sheet conductivity of photoexcited charge carriers in semi-insulating gallium arsenide. Comparison with results obtained using a standard data acquisition scheme shows that the new method minimizes errors originating from fluctuations in the laser system out-put and timing errors in the THz pulse detection. Furthermore, a new organic material, BNA, is proved to be a strong and broadband THz emitter which enables spectroscopy with a bandwidth twice as large as conventional spectroscopy in the field. To access electric fields allowing exploration of THz nonlinear phenomena, field enhancement properties of tapered parallel plate waveguide

Artificial Magnetic Materials: Limitations, Synthesis and Possibilities

Artificial magnetic materials (AMMs) are a type of metamaterials which are engineered to exhibit desirable magnetic properties not found in nature. AMMs are realized by embedding electrically small metallic resonators aligned in parallel planes in a host dielectric medium. In the presence of a magnetic field, an electric current is induced on the inclusions leading to the emergence of an enhanced magnetic response inside the medium at the resonance frequency of the inclusions. AMMs with negative permeability are used to develop single negative, or double negative metamaterials. AMMs with enhanced positive permeability are used to provide magneto-dielectric materials at microwave or optical frequencies where the natural magnetic materials fail to work efficiently. Artificial magnetic materials have proliferating applications in microwave and optical frequency region. Such applications include inversely refracting the light beam, invisibility cloaking, ultra miniaturizing and frequency bandwidth enhancing low profile antennas, planar superlensing, super-sensitive sensing, decoupling proximal high profile antennas, and enhancing solar cells efficiency, among others. AMMs have unique enabling features that allow for these important applications. Fundamental limitations on the performance of artificial magnetic materials have been derived. The first limitation which depends on the generic model of permeability functions expresses that the frequency dispersion in an AMM is limited by the desired operational bandwidth. The other constraints are derived based on the geometrical limitations of inclusions. These limitations are calculated based on a circuit model. Therefore, a formulation for permeability and magnetic susceptibility of the media based on a circuit model is developed. The formulation is in terms of a geometrical parameter that represents the geometrical characteristics of the inclusions such as area, perimeter and curvature, and a physical parameter that represents the physical, structural and fabrication characteristics of the medium. The effect of the newly introduced parameters on the effective permeability of the medium and the magnetic loss tangent are studied. In addition, the constraints and relations are used to methodically design artificial magnetic material meeting specific operational requirements. A novel design methodology based on an introduced analytical formulation for artificial magnetic material with desired properties is implemented. The synthesis methodology is performed in an iterative four-step algorithm. In the first step, the feasibility of the design is tested to meet the fundamental constraints. In consecutive steps, the geometrical and physical factors which are attributed to the area and perimeter of the inclusion are synthesized and calculated. An updated range of the inclusion's area and perimeter is obtained through consecutive iterations. Finally, the outcome of the iterative procedure is checked for geometrical realizability. The strategy behind the design methodology is generic and can be applied to any adopted circuit based model for AMMs. Several generic geometries are introduced to realize any combination of geometrically realizable area and perimeter (s,l) pairs. A realizable geometry is referred to a contour that satisfies Dido's inequality. The generic geometries introduced here can be used to fabricate feasible AMMs. The novel generic geometries not only can be used to enhance magnetic properties, but also they can be configured to provide specific permeability with desired dispersion function over a certain frequency bandwidth with a maximum magnetic loss tangent. The proposed generic geometries are parametric contours with uncorrelated perimeter and area function. Geometries are configured by tuning parameters in order to possess specified perimeter and surface area. The produced contour is considered as the inclusion's shape. The inclusions are accordingly termed Rose curve resonators (RCRs), Corrugated rectangular resonators (CRRs) and Sine oval resonators (SORs). Moreover, the detailed characteristics of the RCR are studied. The RCRs are used as complementary resonators in design of the ground plane in a microstrip stop-band filter, and as the substrate in design of a miniaturized patch antenna. The performance of new designs is compared with the counterpart devices, and the advantages are discussed