Artificiels structurés, présentent des propriétés inédites et des aptitudes uniques pour la manipulation d’ondes en général. L’avènement de ces nouveaux matériaux a permis de dépasser les limites classiques dans tout le domaine de l’acoustique-physique, et d’élargir l’horizon des recherches fondamentales. Plus récemment, une nouvelle classe de structures artificielles, les métasurfaces acoustiques, présentant une valeur ajoutée par rapport aux métamatériaux, avec des avantages en termes de flexibilité, de finesse et de légèreté de structures, a émergé. Inspirés par ces propriétés et fonctionnalités sans précédent, des concepts innovants pour la collecte d’énergie acoustique avec ces deux types de structures artificielles ont été réalisés dans le cadre de cette thèse. Tout d’abord, nous avons développé un concept à base d’un métamatériau en plaque en se basant sur le de l’approche de bande interdite et des modes de défaut permis par le mécanisme de Bragg. Dans la deuxième partie de cette thèse, des métasurfaces d’épaisseur sublongueur d’onde et ultra-minces composées d’unités labyrinthiques ou de résonateurs de Helmholtz ont été conçues et étudiées pour s’atteler à la focalisation et au confinement de l’énergie acoustique. Cette thèse propose un nouveau paradigme de collecte d’énergie des ondes acoustiques à base des métamatériaux et métasurfaces. La collecte de cette énergie acoustique renouvelable, très abondante et actuellement perdue, pourrait particulièrement être utile pour l’industrie de l’aéronautique, de l’automobile, du spatial, de l’urbanisme / Phononic crystals (PCs) and acoustic metamaterials (AMMs), well-known as artificially engineered materials, demonstrate anomalous properties and fascinating capabilities in various kinds of wave manipulations, which have breached the classical barriers and significantly broaden the horizon of the whole acoustics field. As a novel category of AMMs, acoustic metasurfaces share the functionalities of AMMs in exotic yet compelling wave tailoring. Inspired by these extraordinary capabilities, innovative concepts of scavenging acoustic energy with AMMs are primarily conceived and sufficiently explored in this thesis. Generally, a planar AMM acoustic energy harvesting (AEH) system and acoustic metasurfaces AEH systems are theoretically and numerically proposed and analyzed in this dissertation. At first, taking advantage of the properties of band gap and wave localization of defect mode, the AEH system based on planar AMM composed of a defected AMM and a structured piezoelectric material has been proposed and sufficiently analyzed. Secondly, subwavelength (λ/8) and ultrathin (λ/15) metasurfaces with various lateral configurations, composed of labyrinthine and Helmholtz-like elements, respectively, are designed and analyzed to effectively realize the acoustic focusing and AEH. This thesis provides new paradigms of AEH with AMMs and acoustic metasurfaces, which would contribute to the industries of micro electronic devices and noise abatement as well

Ces travaux sont consacrés à la synthèse d'un nouveau type de métamatériaux acoustiques dans le domaine ultrasonore. L'étude porte sur les résonances de cavité, elles peuvent influer sur les différentes grandeurs physiques impliquées dans la propagation des ondes acoustiques. Pour amplifier les résonances, la stratégie a été de mettre en place un contraste de vitesse de phase entre la matrice et les inclusions résonantes. Pour travailler dans le domaine ultrasonore, les techniques de mise en oeuvre sont issues de la microfluidique. Les premiers échantillons sont élaborés par émulsification micrométrique assistée par robotique. Cela permet d'obtenir des polydispersités de l'ordre de 1%. Différents modes de résonances acoustiques ont ainsi été observés. Les recherches ont été poussées jusqu'à l'étude de la polydispersité (1 à 12 %) et l'analyse de systèmes comprenant deux populations de gouttes. Le reste du travail s'est fait en millifluidique avec la mise en forme de dispersions de billes de xérogel de silice avec de plus importants contrastes de vitesse. La synthèse utilisée est une réaction de type sol-gel en milieu basique salin. Le montage millifluidique a été mis en place et calibré pour cette synthèse. La réaction chimique et les particules obtenues ont été caractérisées de nombreuses manières (Raman, rhéologie, mesure de compression, de densité, BET, MEB...). Les mesures acoustiques sur de tels systèmes ont permis de mettre en évidence des gammes de fréquence pour lesquelles l'indice de réfraction acoustique était négatif les plus fortes fractions volumiques (≈ 20%). / This work is dedicated to the synthesis of a new kind of acoustic metamaterials working in the ultrasonic range. The study is based on cavity resonance which can influence physical quantities involved in acoustic wave propagation. For amplifying these resonances, a large phase velocity contrast is required between the matrix and the inclusions.For the ultrasonic range and because of size requirements, the implementation is achieved using microfluidics. First, samples are generated using robotic-assisted emulsification which leads to a very small size polydispersity, around 1%. For these calibrated emulsions, different modes of acoustic resonance are clearly identified. We then generated polydisperse samples on purpose (up to 12%) and correlated the quality factor of the resonances to the size dispersity. Then, in order to enhance the resonance magnitude, silica-based xerogels are synthesized and templated using digital millifluidics. The chemical reaction along with the final xerogel micro-beads (≈ 100 μm radius) are characterized with a large variety of techniques (Raman, rheology, compression and density measurement, BET, SEM...). Acoustic measurements on these systems show that there is a frequency range with a negative acoustic refractive index for a at high enough volume fraction of xerogel particles (20%).

Several microwave devices and antennas that are based on negative-refractive-index transmission-line (NRI-TL) metamaterials are presented in this thesis, which exhibit superior performance features compared to their conventional counterparts. These are a Wilkinson balun, a 1:4 series power divider, a four-element printed dipole array, a leaky-wave antenna, and an electrically small folded-monopole antenna. The Wilkinson balun employs +90° and −90° NRI-TL metamaterial lines at the output branches of a Wilkinson divider, to achieve a six-fold increase in the measured differential output phase bandwidth compared to that of an analogous balun employing transmission lines, while occupying only 55% of the area. The 1:4 series power divider comprises four non-radiating 0° NRI-TL metamaterial lines, each with a compact length of λ0/8, to provide equal power split to all four output ports. Compared to a conventional series power divider employing one-wavelength long transmission lines, the metamaterial divider provides a 154% increase in the measured through-power bandwidth, while occupying only 54% of the area. The metamaterial series power dividing concept is also applied to a four-element fully-printed dipole array that is designed to radiate at broadside, in order to demonstrate that the array exhibits reduced beam squinting characteristics. It is shown that the metamaterial-fed array has a measured scan-angle bandwidth that is 173% greater than an array that is fed using a conventional low-pass loaded line. The reduced-beam squinting property that NRI-TL metamaterial lines offer is subsequently exploited to create a leaky-wave antenna that radiates a near-fixed beam in the forward +45° direction, with an average measured beam squint of only 0.031°/MHz. This is achieved by operating the antenna in the upper right-handed band where the phase and group velocities are the closest to the speed of light. Finally, an electrically small antenna comprising four 0° NRI-TL metamaterial unit cells is presented which supports a predominantly even-mode current, thus enabling it to be modeled as a multi-arm folded monopole. This significantly increases its radiation resistance, which allows it to be matched to 50 Ω, while maintaining a high measured efficiency of 70%.

Several microwave devices and antennas that are based on negative-refractive-index transmission-line (NRI-TL) metamaterials are presented in this thesis, which exhibit superior performance features compared to their conventional counterparts. These are a Wilkinson balun, a 1:4 series power divider, a four-element printed dipole array, a leaky-wave antenna, and an electrically small folded-monopole antenna. The Wilkinson balun employs +90° and −90° NRI-TL metamaterial lines at the output branches of a Wilkinson divider, to achieve a six-fold increase in the measured differential output phase bandwidth compared to that of an analogous balun employing transmission lines, while occupying only 55% of the area. The 1:4 series power divider comprises four non-radiating 0° NRI-TL metamaterial lines, each with a compact length of λ0/8, to provide equal power split to all four output ports. Compared to a conventional series power divider employing one-wavelength long transmission lines, the metamaterial divider provides a 154% increase in the measured through-power bandwidth, while occupying only 54% of the area. The metamaterial series power dividing concept is also applied to a four-element fully-printed dipole array that is designed to radiate at broadside, in order to demonstrate that the array exhibits reduced beam squinting characteristics. It is shown that the metamaterial-fed array has a measured scan-angle bandwidth that is 173% greater than an array that is fed using a conventional low-pass loaded line. The reduced-beam squinting property that NRI-TL metamaterial lines offer is subsequently exploited to create a leaky-wave antenna that radiates a near-fixed beam in the forward +45° direction, with an average measured beam squint of only 0.031°/MHz. This is achieved by operating the antenna in the upper right-handed band where the phase and group velocities are the closest to the speed of light. Finally, an electrically small antenna comprising four 0° NRI-TL metamaterial unit cells is presented which supports a predominantly even-mode current, thus enabling it to be modeled as a multi-arm folded monopole. This significantly increases its radiation resistance, which allows it to be matched to 50 Ω, while maintaining a high measured efficiency of 70%.

Metamaterials attracted significant attention in recent years due to their potential to create novel devices that exhibit specific electromagnetic properties. In this thesis, we investigated transmission and propagation properties of novel metamaterial structures. Electromagnetic properties of metamaterials are characterized and the resonance mechanism of Split Ring Resonator (SRR) structure is investigated. Furthermore, a recent lefthanded metamaterial structure for microwave regime called Fishnet-type metamaterial is studied. We demonstrated the left-handed transmission and negative phase velocity in Fishnet Structures. Finally, we proposed and successfully demonstrated novel approaches that utilize the resonant behavior of SRR structures to enhance the transmission of electromagnetic waves through sub-wavelength apertures at microwave frequency regime. We investigated the transmission enhancement of electromagnetic waves through a sub-wavelength aperture by placing SRR structures in front of the aperture and also by changing the aperture shape as SRR-shaped apertures. The incident electromagnetic wave is effectively coupled to the sub-wavelength aperture causing a strong localization of electromagnetic field in the sub-wavelength aperture. Localized electromagnetic wave gives rise to enhanced transmission from a single sub-wavelength aperture. The proposed structures are designed, simulated, fabricated and measured. The simulations and experimental results are in good agreement and shows significant enhancement of electromagnetic wave transmission through sub-wavelength apertures by utilizing proposed novel structures. Radius (r) of the sub-wavelength aperture is approximately twenty times smaller than the incident wavelength (r/&amp / #955 / ~0.05). This is the smallest aperture size to wavelength ratio in the contemporary literature according to our knowledge.

This dissertation is focused on the design, fabrication, and characterization of novel metamaterials in microwave and terahertz regions with the following outcomes: A planar &micro / -negative metamaterial structure, called double-sided SRR (DSRR), is proposed in the first part of this study. DSRR combines the features of a conventional split ring resonator (SRR) and a broadside-coupled SRR (BC-SRR) to obtain much better miniaturization at microwave frequencies for a given physical cell size. In addition to DSRR, double-sided multiple SRR (DMSRR), double-sided spiral resonator (DSR), and double-sided U-spiral resonator (DUSR) have been shown to provide smaller electrical sizes than their single-sided versions under magnetic excitation. In the second part of this dissertation, a novel multi-band tunable metamaterial topology, called micro-split SRR (MSSRR), is proposed. In addition to that, a novel magnetic resonator structure named single loop resonator (SLR) is suggested to provide two separate magnetic resonance frequencies in addition to an electric resonance in microwave region. In the third part, two different frequency tunable metamaterial topologies called BC-SRR and gap-to-gap SRR are designed, fabricated and characterized at terahertz frequencies with electrical excitation for the first time. In those designs, frequency tuning based on variations in near field coupling is obtained by in-plane horizontal or vertical displacements of the two SRR layers. The values of frequency shifts obtained for these tunable metamaterial structures are reported to be the highest values obtained in literature so far. Finally, in the last part of this dissertation, novel double-sided metamaterial based sensor topologies are suggested and their feasibility studies are presented.

This thesis focuses mostly on investigating different potential applications of meta-transmission line (TL), particularly composite right/left handed (CRLH) TL, and analyzing some new phenomena and applications of meta-TL, mostly left-handed (LH) TL. Realization principle will also be studied.   First, the fundamental electromagnetic properties of propagation in the presence of left-handed material (LHM) are illustrated. The transmission line approach for LHM design is described together with a brief review of the transmission line theory. As a generalized model for LHM TL, CRLH TL provides very unique phase response, such as dual-band operation, bandwidth enhancement, nonlinear dispersion, and the existence of critical frequency with zero phase velocity. Based on these properties, some novel applications of the existing CRLH transmission lines are then given, including a notch filter, a diplexer, a broadband phase shifter, a broadband balun, and a dual band rat-ring coupler. In the design of notch filters and diplexers, CRLH TL shunt stub is utilized to provide high frequency selectivity due to the existence of critical frequency with zero phase velocity. The proposed wideband Wilkinson balun, which comprises of one section of conventional transmission lines and one section of CRLH-TL, is shown to have a 180°±10° bandwidth of 2.12 GHz centered at 1.5 GHz. In the analysis of the dual band rat-ring couplers, a generalized formulation of the requirements about impedances and electrical length of the branches are derived, and as an example, a compact dual-band rat-race coupler is designed utilizing the balanced CRLH TL. Furthermore, a low pass filter is also proposed and designed based on a single (epsilon) negative coplanar waveguide (CPW).Various principles to realize meta-transmission lines are investigated. The main conclusions are listed below:Ÿ         Dual composite right/left handed (D-CRLH) transmission line, which is the dual structure of conventional CRLH TL, shows opposite handedness in the high frequencies and low frequencies with CRLH TL. Meanwhile, in the practical implementation, D-CRLH TL always shows a sharp stopband. A notch filter and a dual-band balun are designed based on D-CRLH TL. Ÿ         The lattice type transmission line (LT-TL) shows the same magnitude response with the conventional right-handed (RH) TL, but a constant phase difference in the phase response over a wide frequency band. A wideband rat-race coupler is proposed as an application of the LT-TL. Ÿ         Finger-shorted interdigital capacitors (FSIDCs) are analyzed and it is shown that FSIDC alone can act as a left-handed transmission line. The value of the reactive elements (inductors and capacitors) in the equivalent circuit model is determined by the dimensions of FSIDC. The relationship between them is analyzed.Later, transmission line loaded with negative-impedance-converted inductors and capacitors is illustrated as the first non-dispersive LH transmission line. The design of a negative series impedance converter is given in detail and a wideband power divider is designed as a potential application of the newly proposed meta-transmission lines in is also given. The final part of the thesis focuses on the study of microstrip lines loaded with complementary split ring resonators (SRRs). An equivalent circuit is made for this structure. The circuit model is verified by the experimental results of cases with different periodic lengths. Thereafter, a meander line split ring resonator (MLSRR) is presented. It shows dual band property and the miniature prototypes of complementary MLSRR loaded transmission lines are fabricated. By comparing the resonance frequencies of complementary MLSRR and multiple SRR, it is shown that the complementary MLSRR is very compact. C-MLSRR is applied in rejecting unnecessary frequencies in the ultra wideband antennas. / QC 20100720

This thesis introduces efficient numerical techniques for the analysis of novel electromagnetic metamaterials. The modelling is based on a Method of Moments modal analysis in conjunction with an interpolation scheme, which significantly accelerates the computations. Triangular basis functions are used that allow for modelling of arbitrary shaped metallic elements. Unlike the conventional methods, impedance interpolation is applied to derive the dispersion characteristics of planar periodic structures. With these techniques, the plane wave and the surface wave responses of fractal structures have been studied by means of transmission coefficients and dispersion diagrams. The multiband properties and the compactness of the proposed structures are presented. Based on this method, novel planar left-handed metamaterials are also proposed. Verifications of the left-handedness are presented by means of full wave simulation of finite planar arrays using commercial software and lab measurement. The structures are simple, readily scalable to higher frequencies and compatible with low-cost fabrication techniques.

Les métamatériaux forment une nouvelle classe de matériaux composites artificiels aux propriétésélectromagnétiques extraordinaires. Ces propriétés inédites reposent sur l’inclusion, dans le métamatériau,de résonateurs plasmoniques dont la fabrication et l’assemblage posent un défi auquel se heurtent lestechniques de gravure habituellement utilisées. Cette thèse est consacrée à la de ces nano-résonateurs demorphologie framboise, constitués d’un coeur diélectrique et de nanoparticules plasmoniques, sphériquesou triangulaires. Ces objets ont été élaborés en grande quantité tout en respectant la contrainte du milieueffectif qui impose des tailles très inférieures à la longueur d’onde. La réponse optique des nanorésonateursindividuels a été mesurée et comparée aux modélisations. Des résonances électriques etmagnétiques intenses ont été mises en évidence. Ces objets sont prometteurs pour la première réalisationde matériau massif à perméabilité magnétique artificielle. / Metamaterials are artificial composites materials exhibiting extraordinary electromagnetic properties.These original properties are based on the inclusion in the metamaterial of plasmonic resonators for whichthe fabrication and the assembly remain challenging. This thesis is dedicated to the synthesis throughcolloidal approach and the structural and optical characterization of these “raspberry-like nanoresonators”constituted of a dielectric core and spherical or triangular plasmonic nanoparticles.These objects are elaborated in large amount while respecting the constraint of effective medium whichrequires sizes much smaller than the wavelength. The optical response of individual nanoresonators wasmeasured and compared with theoretical simulations. Intense electric and magnetic resonances arehighlighted. These objects are promising for the first elaboration of a bulk material with artificial magneticpermeability.

This report examines the cross sections of silver microresonators subjected to an incident light with different polarization. The microresonators had different geometries with and without broken symmetries. Cross section profiles for different microresonator configurations are interesting for the division of Material Physics, Uppsala University, when designing metamaterials to tune the optical response of the material. The goal is to form an insight of how the optical response can be tuned by choosing different geometries, varying the size and polarization of the incident light. In this project computer simulations in COMSOL were made to simulate the optical response of different microresonators. When the incident light interact with the silver microresonators plasmonic excitations is generated which in turn interacts with the light changing the phase and therefore the optical response. By increasing the radius of the disk silver microresonantors the resonance was found to shift to lower energies. For a geometry with a disk microresonator inside a ring microresonator the Fano resonances were dependent of the radius of the disk microresonator.