Presented is a radiometric sensor and associated electromagnetic propagation models, developed to facilitate non-invasive core body temperature extraction. The system has been designed as a close-proximity sensor to detect thermal emissions radiated from deep-seated tissue 1 cm – 3 cm inside the human body. The sensor is intended for close proximity health monitoring applications, with potential implications for deployment into the improved astronaut liquid cooling garment (LCG). The sensor is developed for high accuracy and resolution. Therefore, certain design issues that distort the close proximity measurement have been identified and resolved. An integrated cavity-backed slot antenna (CBSA) is designed to account for antenna performance degradation, which occurs in the near field of the human body. A mathematical Non-Contact Model (NCM) is subsequently used to correlate the observed brightness temperature to the subsurface temperature, while accounting for artifacts induced by the sensor’s remote positioning from the specimen. In addition a tissue propagation model (TPM) is derived to model incoherent propagation of thermal emissions through the human body, and accounts for dielectric mismatch and losses throughout the intervening tissue layers. The measurement test bed is comprised of layered phantoms configured to mimic the electromagnetic characteristics of a human stomach volume; hence defines the human core model (HCM). A drop in core body temperature is simulated via the HCM, as the sensor monitors the brightness temperature at an offset distance of approximately 7 mm. The data is processes through the NCM and TPM; yielding percent error values < 3%. This study demonstrates that radiometric sensors are indeed capable of subsurface tissue monitoring from the near field of the body. However, the following components are vital to achieving an accurate measurement, and are addressed in this work: 1) the antenna must be designed for optimum functionality in close proximity to biological media; 2) a multilayer phantom model is needed to accurately emulate the point of clinical diagnosis across the tissue depth; 3) certain parameters of the non-contact measurement must be known to a high degree of accuracy; and 4) a tissue propagation model is necessary to account for electromagnetic propagation effects through the stratified tissue.

Near Field Communication (NFC) är en teknik som möjliggjort utvecklingen av vardagliga betalningar med hjälp av mobiltelefonen. I Sverige är betalningar med NFC-tekniken i mobiltelefoner fortfarande i introduktionsfasen. För att denna teknik ska ha möjlighet att fungera som ett komplement till redan befintliga betallösningar, granskas därför möjligheten för NFC-teknik som betallösningsmetod med inriktning på säkerhetsaspekter. Syftet med uppsatsen är att granska säkerhetsaspekter för NFC-teknik som mobil betallösningsmetod samt analysera dessa aspekter för att få djupare kunskap för NFC-teknologins möjligheter. Kunskapen har erhållits genom en litteraturstudie samt kompletterande av en intervju för att få bredd i informationsbehandlingen. Resultatet av studien visar att NFC-teknologin som betallösningsmetod kan påverkas av ett antal säkerhetsaspekter. För att NFC-tekniken skall nå en bredd i marknaden måste flertalet aktörer samarbeta för en standardisering i användandet av tekniken. / Near Field Communication (NFC) is a technology that enables the development of payments using the mobile phone. In Sweden, payments with NFC technology in mobile phones are still in the introductory phase. To ensure that the proposed technology can be utilized as a complement to existing payment options, one must consider the safety aspects of said construct. In this thesis we will review the technology with a focus on safety aspects. The purpose of this thesis is to review the security aspects of NFC technology for mobile payment and analyze these aspects in order to gain deeper knowledge of NFC technology opportunities. The knowledge has been obtained through a literature review, complemented by an interview to get a wide knowledge about the information. The results of the study show that NFC technology as a payment option can be affected by a number of safety issues. To ensure a viable market share, operators utilizing NFC technology must cooperate to standardize the implementation.

This work presents the first demonstration of a semiconductor based plasmonic near-field superlens, utilizing highly doped GaAs to generate infrared optical images with a spatial resolution beyond the difraction limit. Being easily transferable to other semiconductor materials, the concept described in this thesis can be exploited to realize spectrally adjustable superlenses in a wide spectral range. The idea of superlensing has been introduced theoretically in 2000, followed by numerous publications including experimental studies. The effect initiated great interest in optics, since in contrast to difraction limited conventional optical microscopy it enables subwavelength resolved imaging by reconstructing the evanescent waves emerging from an object. With techniques like scanning near-field optical microscopy (SNOM) and stimulated emission depletion (STED) being already successfully established to overcome the conventional restrictions, the concept of superlensing provides a novel, different route towards high resolution. Superlensing is a resonant phenomenon, relying either on the excitation of surface plasmons in metallic systems or on phonon resonances in dielectric structures. In this respect a superlens based on doped semiconductor benefits from the potential to be controlled in its operational wavelength by shifting the plasma frequency through adjustment of the free carrier concentration. For a proof of principle demonstration, we investigate a superlens consisting of a highly n-doped GaAs layer (n = 4 x 10^18 cm-3) sandwiched between two intrinsic layers. Recording near-field images of subwavelength sized gold stripes through the trilayer structure by means of SNOM in combination with a free-electron laser, we observe both enhanced signal and improved spatial resolution at radiation wavelengths close to l = 22 µm, which is in excellent agreement with simulations based on the Drude-Lorentz model of free electrons. Here, comparative investigations of a purely intrinsic reference sample confirm that the effect is mediated by the charge carriers within the doped layer. Furthermore, slightly differently doped samples provide indications for the expected spectral shift of the resonance. According to our calculations, the wavelength range to be exploited by n-GaAs based superlenses reaches far into the terahertz region, whereas other semiconductor materials are required to explore the near infrared.

The objective of the proposed research is the design and fabrication of a novel stand-alone wireless robust system with enhanced hardware-enabled authentication and anti-counterfeiting capabilities. The system consists of two major components; the near-field certificates of authenticity (CoA), which serve as authenticity vouchers of the products they are attached to, and a microcontroller-enabled, low-power and low-cost reader. Small-sized passive physical three-dimensional structures that are composed of extremely cheap conductive and dielectric materials are shown to yield a unique and repeatable RF signature in a small portion of the frequency spectrum when brought in the reactive and radiating near-field regions of an array of miniature antennas. The multidimensional features of these CoAs, or in other words their signature or fingerprint, are cryptographically signed and digitally stored. The contactless signature validation procedure, in which an attempt to associate the near-field signature response of the physical CoA with the digitized signature, is carried out by the reader designed and fabricated. This low-cost reader operates autonomously and in an offline fashion. The feasibility and performance robustness of the system, in terms of accuracy, consistency and speed of capturing of the signatures, is rigorously assessed with a wide array of tests. Moreover, the entropy, or uncertainty, of the signatures generated by the system are empirically quantified and verified to achieve a virtually impossible false alarm. The aforementioned characteristics of the realized authentication system make it applicable to a vast array of physical objects that needs protection against counterfeiters.

Le principe de la RMN repose sur la détection de l'aimantation provenant de spin des noyaux atomiques tels que 13C, 31P et 1H. L'échantillon est placé dans un champ magnétique statique, qui polarise l'ensemble des spins. Ces derniers sont ensuite excités par les impulsions radiofréquences (environ un mètre de longueur d'onde), qui font basculer l'aimantation de ces spins dans le plan transversal. Lorsque l'aimantation retourne à sa position d'équilibre, il génère un champ électromagnétique qui est classiquement détecté par une antenne réceptrice (bobine avec un circuit d'accord/d'adaptation) à couplage inductif. Dans ce travail, nous proposons l'utilisation d'une sonde de taille micrométrique placée au voisinage de l'objet d'intérêt, à une distance bien plus courte que la longueur d'onde du signal de RMN rayonné. Notre microsonde présente des caractéristiques innovantes (i) un couplage capacitif (composante du champ électrique), (ii) une dimension réduite pour un positionnement précis, qui assure la détection du signal de RMN de l'échantillon et (iii) une détection à large bande, ce qui permet de l'utiliser pour détecter différents noyaux sans être accordée à la fréquence de Larmor. Pour vous présenter cette nouvelle alternative, les outils nécessaires à la compréhension de ce travail, en l'occurrence le principe de la RMN et de l'IRM et une introduction de la théorie du champ proche électrique sont donnés. Nous avons fait aussi un état de l'art des méthodes et techniques existant pour mesurer le signal RMN afin de recenser les avantages qu'un tel système (méthode : couplage capacitif et dispositif : microsonde de champ proche) peut apporter à la technique RMN. Ensuite, nous avons caractérisé notre microsonde pour améliorer sa détection hyper localisée, nous avons démontré que le signal RMN récupéré par notre antenne peut être décrit par l'expression du champ proche électrique :E(x, z) = A(Kz ) exp(i(z/L)) exp(−x/L) + Terme Propagatif. Enfin, nous avons appliqué notre système à des études RMN comme la spectroscopie, la relaxométrie ou encore de l'imagerie RMN. Nous avons aussi énoncé certains projets potentiels à la continuité de ce travail. / The principle of NMR is based on the detection of the magnetization originating from the spin of atomic nuclei such as 13C, 31P and 1H. The sample is placed in a static magnetic field, which polarizes the ensemble of spins and it is excited by radiofrequency pulses (wavelength about one meter), that tilt the axis of the magnetization. When the magnetization returns to equilibrium, it generates an electromagnetic field which is classically detected by a receiving antenna (coil with atuning/matching circuit) in inductive coupling.In this work, we propose the use of a micrometer-sized probe positioned in the vicinity of the object of interest, at a distance well shorter than the wavelength of the radiated NMR signal.Our microprobe presents innovative characteristics (i) a capacitive coupling (electric field component), (ii) reduced dimensions for an accurate positioning, which ensure the detection of NMR signal from the sample and (iii) it has a broadband, which allows use to detect any nuclei without being tuned to the Larmor frequency.To introduce you this new alternative, the tools necessary to the understanding of this work, in this case the principle of NMR/MRI and an introduction of the theory of the electric near field are given initially.We made also a state of the art of existing methods and techniques for measuring the NMR signal to identify the benefits that such a system (method : capacitive coupling and device : microprobe near field) can bring to the NMR technique.Then, we have characterized our microprobe to enhance its localized detection due to its small size (127 μm in diameter and 2mm in length). In this stage of characterization, we demonstrated that the NMR signal recovered by our antenna can be described by the electric near field expression :E(x, z) = A(Kz ) exp(i(z/L)) exp(−x/L) +Propagative TermFinally, we applied our system to make NMR studies such as spectroscopy, the relaxometry and NMR Imaging. We have outlined some potential projects to the continuity of this work.

Two compact planar crossed-dipole antennas loaded with near-field resonant parasitic (NFRP) elements are reported. The NFRP and crossed-dipole elements are designed for the desired circularly polarized (CP) radiation. By placing the NFRP element over the driven element at angles of 0 degrees and 45 degrees, respectively, dual-band and broadband CP antennas are realized. All radiating elements of antennas are 35 mm x 35 mm x 0.508 mm (0.187 lambda(0) x 0.187 lambda(0) x 0.0027 lambda(0) at 1.6 GHz) in size. The dual-band CP antenna has a measured vertical bar S-11 vertical bar < -10-dB bandwidth of 226 MHz (1.473-1.699 GHz) and measured 3-dB axial ratio (AR) bandwidths of 12 MHz (1.530-1.542 GHz) and 35 MHz (1.580-1.615 GHz) with minimum AR CP frequencies of 1.535 GHz (AR = 0.26 dB) and 1.595 GHz (AR = 2.08 dB), respectively. The broadband CP antenna has a measured vertical bar S-11 vertical bar< -10-dB bandwidth of 218 MHz (1.491-1.709 GHz) and a 3-dB AR bandwidth of 145 MHz (1.490-1.635 GHz). These compact antennas yield bidirectional electromagnetic fields with high radiation efficiency across their operational bandwidths.

Les nanostructures métalliques ont la capacité de supporter des résonances de plasmons de surface localisés se caractérisant par une oscillation collective des électrons libres du métal. Ce phénomène, connu pour générer localement un champ électrique intense, peut notamment être exploité afin d'exalter les processus d'optique non-linéaire à l'échelle nanométrique. Au cours de cette thèse, nous nous sommes intéressés au processus de génération de second harmonique (SHG) de nanostructures en aluminium et en or. Tout d'abord, nous avons étudié l'origine du processus non-linéaire et mis en évidence le rôle important joué, dans l'or, par la contribution non-locale, issue des gradients de champ dans le volume de la nanostructure. Ensuite, nous avons montré, en associant un phénomène de double résonance et un accord des modes plasmoniques à l'excitation et à l'émission, qu'il est possible d'exalter fortement la réponse harmonique d'une nanoantenne compacte en aluminium. Dans l'optique d'obtenir une intensité non-linéaire encore plus importante, une stratégie est de coupler ces nanostructures à un nanocristal non-linéaire afin de bénéficier à la fois de la forte exaltation du champ générée par le métal et de la non-linéarité du cristal. Afin d'optimiser l'intensité harmonique générée par ces structures hybrides, disposer de nanocristaux possédant une forte non-linéarité intrinsèque est nécessaire. C'est pourquoi, au cours de cette thèse, nous avons mesuré la réponse harmonique de nanocristaux d'iodates de lantane isolés, afin d'estimer leur potentiel pour intégrer ce type de structure. De plus, un microscope optique en champ proche a été mis en place sur le dispositif expérimental permettant la manipulation de nanocristaux à proximité de structures métalliques. Cette thèse, en apportant de nouveaux éléments pour comprendre et optimiser le processus de SHG dans les nanostructures plasmoniques, offre de nouvelles perspectives pour confectionner des composants optiques efficaces pour la conversion de fréquence à l'échelle nanométrique. / Plasmonic nanostructures have the ability to support localised surface plasmon resonances characterized by a collective oscillation of the free electrons in metal. This phenomenon, know to generate an intense local field, can be used to enhance nonlinear optical processes at the nanoscale level. In this thesis, we have investigated the second harmonic generation (SHG) process in aluminum and gold nanostructures. First, we have studied the origin of this nonlinear process and highlighted the major role played, in gold, by the bulk nonlocal contribution, originating from the field gradients inside the nanostructure volume. Then, we pointed out, by achieving a double resonance regime associated with a plasmonic mode matching at the excitation and emission, the possibility to enhance significantly the harmonic response of compact aluminum nanoantennas. In order to increase even more the nonlinear intensity, an idea is to couple these nanostructures to a nonlinear nanocrystal to benficiate both from the field enhancement provided by the metallic nanoantenna and from the nonlinearity of the nanocrystal. To optimise the harmonic intensity generated by these hybrid structures, have nanocrystals with a strong intrinsic nonlinearity is required. To this end, we have measured the harmonic response of single latanide iodate nanocrystals, in order to evaluate their ability to integrate this type of structure. Moreover, we have implemented a near-field optical microscope used to manipulate nancorystals in the vincinity of metallic nanostructures. This thesis, by bringing new elements to understand and optimise the SHG process in plasmonic nanostructures, provides new perspectives to elaborate efficient optical components to frequency conversion at the nanoscale.

Dans le domaine de la sécurisation des circuits intégrés, tel que les cartes à puce, les concepteurs de circuits sont contraints à innover, inlassablement, afin de trouver de nouvelles parades aux nouvelles attaques, notamment par canaux cachés. En effet, ces attaques, comme l'analyse des émissions électromagnétiques, permettent d'extraire des informations, contenues à l'intérieur des circuits, sensées être secrètes. Partant de ce constat, dans cette thèse, nous nous sommes focalisés sur l'étude et l'analyse électromagnétique et ce afin de quantifier les possibilités de ces attaques. Ce manuscrit est organisé de la manière qui suit. Dans un premier temps, une plateforme de mesures des émissions électromagnétiques temporelles, que nous avons développées, est présentée, ainsi que des résultats qui ont été obtenus, avec celle-ci, sur différents circuits. A partir de ces résultats, une synthèse des possibilités, relatives à la menace sécuritaire que constituent les analyses électromagnétiques est proposée ainsi que, des propositions de solutions, visant à réduire le rayonnement électromagnétique des circuits intégrés. Dans un second temps, nous nous sommes intéressés aux méthodes de simulation de ces émissions électromagnétiques. Un état de l'art, des outils de simulation existants aujourd'hui, nous a permis de mettre en évidence qu'aucun d'eux ne permet d'avoir une résolution suffisamment fine en termes d'émissions électromagnétiques. Afin de combler ce manque, un flot de simulation a été développé. Pour valider ce flot, une comparaison entre les résultats de mesure et les résultats de simulation a été effectuée. / In the area of secure integrated circuits, such as smart cards, circuit designers are always looking to innovate to find new countermeasures against attacks by the various side channels that exist today. Indeed, side channels attacks such as the analysis of electromagnetic emissions permit to extract secret information contained in circuits. Based on this observation, in this thesis, we focused on the study of electromagnetic analysis to observe the analysis possibilities. This manuscript is organized as follows. Initially, we presented a measurement system for electromagnetic emissions in time domain, and the results obtained on different circuits. From these results, a summary of opportunities, relating to the security threat, posed by electromagnetic analysis, is proposed as well as solutions proposals to reduce electromagnetic radiations of integrated circuits. In a second step, we are interested in the simulation of electromagnetic emissions. A state of the art of simulation tools which exist today, has allowed us to demonstrate that none of them allowed to have a fine enough resolution in terms of electromagnetic emissions. To fill this gap, a simulation tool has been developed and to validate this flow, a comparison between measurement results and simulation results was performed.

This thesis presents studies of novel terahertz photonic devices, including photoconductive optoelectronic devices and guided-wave components, aimed at the development of next-generation terahertz systems. In chapter 2, a scalable interdigitated THz transmitter is designed to increase the output power and compared with a conventional 50 μm coplanar transmitter. In chapter 3, we compare four different receivers with different antenna geometries in terms of bandwidth and sensitivity. Then we describe a photoconductive near-field detector with a subwavelength aperture and its system integration and characterization. In chapter 4, a parallel metal plate waveguide is designed with an integrated step inside the waveguide that can couple to higher order TM modes efficiently from the TEM mode. In this chapter, we also experimentally and numerically study a 2-dimensionally tapered parallel plate waveguide, by which a free-space THz beam can be focused into a deep subwavelength-scale volume. In chapter 5, a parallel thin dielectric film waveguide is used to explore the guiding mechanism of an antiresonant optical reflection waveguide. Cylindrical silica single capillaries and a microstructured capillary, which guide in a similar way, are characterized in terms of mode profiles and attenuation. In chapter 6, we study oblique transmission through freestanding thin nickel films, which are perforated with periodic conical hole arrays. Surface modes can be supported by both metallic surfaces with different nonlinear dispersion curves, which results in spectral interferences in a near-field region when the surface modes couple out of the waveguide into free space.

Increasingly, goods and services are purchased over the Internet without any form of physical currency. This practice, often called e-commerce, offers sellers and buyers a convenient way to trade globally as no physical currency must change hands and buyers from anywhere in the world can browse online store fronts from around the globe. Nevertheless, many transactions still require a physical presence. For these sorts of transactions, a new technology called Near Field Communication has emerged to provide buyers with some of the conveniences of e-commerce while still allowing them to purchase goods locally. Near Field Communication (NFC), an evolution of Radio-Frequency Identification (RFID), allows one electronic device to transmit short messages to another nearby device. A buyer can store his or her payment information on a tag and a cashier can retrieve that information with an appropriate reader. Advanced devices can store payment information for multiple credit and debit cards as well as gift cards and other credentials. By consolidating all of these payment forms into a single device, the buyer has fewer objects to carry with her. Further, proper implementation of such a device can offer increased security over plastic cards in the form of advanced encryption. Using a testing platform consisting of commercial, off-the-shelf components, this dissertation investigates the security of the NFC physical-layer protocols as well as the primary NFC security protocol, NFC-SEC. In addition, it analyzes a situation in which the NFC protocols appear to break, potentially compromising sensitive data. Finally, this dissertation provides a proof of security for the NFC-SEC-1 variation of NFC-SEC.