abstract: This thesis summarizes the research work carried out on design, modeling and simulation of semiconductor nanophotonic devices. The research includes design of nanowire (NW) lasers, modeling of active plasmonic waveguides, design of plasmonic nano-lasers, and design of all-semiconductor plasmonic systems. For the NW part, a comparative study of electrical injection in the longitudinal p-i-n and coaxial p-n core-shell NWs was performed. It is found that high density carriers can be efficiently injected into and confined in the core-shell structure. The required bias voltage and doping concentrations in the core-shell structure are smaller than those in the longitudinal p-i-n structure. A new device structure with core-shell configuration at the p and n contact regions for electrically driven single NW laser was proposed. Through a comprehensive design trade-off between threshold gain and threshold voltage, room temperature lasing has been proved in the laser with low threshold current and large output efficiency. For the plasmonic part, the propagation of surface plasmon polariton (SPP) in a metal-semiconductor-metal structure where semiconductor is highly excited to have an optical gain was investigated. It is shown that near the resonance the SPP mode experiences an unexpected giant modal gain that is 1000 times of the material gain in the semiconductor and the corresponding confinement factor is as high as 105. The physical origin of the giant modal gain is the slowing down of the average energy propagation in the structure. Secondly, SPP modes lasing in a metal-insulator-semiconductor multi-layer structure was investigated. It is shown that the lasing threshold can be reduced by structural optimization. A specific design example was optimized using AlGaAs/GaAs/AlGaAs single quantum well sandwiched between silver layers. This cavity has a physical volume of 1.5×10-4 λ03 which is the smallest nanolaser reported so far. Finally, the all-semiconductor based plasmonics was studied. It is found that InAs is superior to other common semiconductors for plasmonic application in mid-infrared range. A plasmonic system made of InAs, GaSb and AlSb layers, consisting of a plasmonic source, waveguide and detector was proposed. This on-chip integrated system is realizable in a single epitaxial growth process. / Dissertation/Thesis / Ph.D. Electrical Engineering 2012

Afin de répondre aux besoins croissants d’équipements de communication pour les applications spatiales, il est important de réduire, le plus possible, la taille et la masse de l’équipement des satellites. Cela conduit à une réduction des coûts de lancement des satellites sur leur orbite ou laisse la possibilité d’ajouter des équipements dans la fusée. Ceci compte aussi pour les composants radioélectriques. L’objectif étant de réduire les dimensions sans pour autant détériorer les performances en rayonnement (directivité, polarisation croisée, bande monomode, etc.). Il est possible de contrôler la propagation des ondes électromagnétiques dans les antennes cornets et les guides d’onde à l’aide de surfaces anisotropes (corrugations, métamatériaux). Ainsi, contrairement à ce que prédisent les lois physiques sur la propagation et le rayonnement d’ondes électromagnétiques dans des structures classiques, les performances des structures à parois anisotropes peuvent être radicalement améliorées : pour le guide d’onde, réduction de la fréquence de coupure ; pour l’antenne cornet, amélioration de la directivité ou réduction du niveau des lobes secondaires. D’après l’état de l’art, même si les résultats de simulations et de mesures obtenus sont très prometteurs, le dimensionnement de la structure des métamatériaux est sujet à optimisation, donc gourmand en ressources informatiques. L’apport principal de cette thèse a été de développer une nouvelle méthodologie de conception s’appuyant sur une Théorie Modale Elargie (TME) analytique pour des guides d’onde à parois anisotropes. Elle permet de dimensionner très rapidement des surfaces à métamatériaux les plus adaptées aux applications requises. Un prototype de guide d’onde et un prototype d’antenne ont été conçus, fabriqués et mesurés grâce à cette méthodologie. Les résultats obtenus démontrent l’intérêt, l'efficacité et le caractère général de la méthode proposée pour la conception de dispositifs hyperfréquences guidés à parois anisotropes. / In space applications, one of the biggest challenges is to reduce the size and mass of equipment, in order to reduce the costs of the rocket launch. For RF components, this has to be done without lowering RF performance (directivity, crosspolarization, single-mode bandwidth, etc.). The challenge is all the more problematic in the case of used horn antennas and waveguides because of their relatively large size. It has been shown that the use of anisotropic surfaces (i.e. corrugations and metamaterials) on the inside walls of guided RF structure makes it possible to influence and control the way electromagnetic waves travel, enabling new devices with radically different and improved performances : for waveguides, reduction of the cuto&# 64256; frequency ; for horn antennas, improvement of the directivity or a reduction of the side lobes. A state of the art of previous work done on metamaterial horn antennas pointed out that, even if the obtained and presented results seem very promising, the procedure to obtain the optimized RF structure is very time-consuming and requires considerable computer resources. The main contribution of this PhD work was to develop a new methodology based on the analytical Modal Expansion Theory (MET) for waveguides with anisotropic walls. This methodology makes it possible to optimize very rapidly the dimensions of the metamaterial surfaces adjusted to the required application. A metamaterial waveguide and antenna prototype have been designed, realized and measured thanks to this methodology. The results obtained demonstrate the usefulness, effectiveness and general applicability of the method developed for the design of RF structures with anisotropic walls.

Abstract In this thesis, we study quantum waveguides and their spectral properties. A quantum waveguide is a system of narrow strips or tubes. That is, the waveguide has large longitudinal but small transverse sizes. The study of quantum waveguides is essential in the semi-conductor industry, and the waveguides are used to model the electron behavior in these devices. We consider two- and three-dimensional waveguides with sharp bends and question whether the quantum particle can propagate in the waveguide. It is well known that a certain type of bends and bulges cause the resonance phenomena, that is, at some energy levels the electron motion is localized in a finite area, and the propagation is disturbed. The study of waveguides leads to the interesting field of mathematics - the spectral analysis of differential operators. For a waveguide having high purity and a crystalline structure, the electron motion can be considered as a free particle motion with effective mass. This gives rise to the spectral problem, that is, the eigenvalue problem of the Laplace operator. On the boundary we set the Dirichlet conditions. This thesis consists of three parts and in each part we study waveguides which form sharp bends in the junctions where two or three outlets are joined together. To be precise, we consider waveguides which resemble the letters Y, Z, and C. We study the discrete spectrum corresponding to these waveguides and the behavior of the bound modes when the geometry is slightly changed. For this, we apply the variational, numerical, and asymptotic methods. For the Y-shaped waveguide, we let one outlet become wider than the others and found that a critical width exists, so that for smaller width values, exactly one bound state exists, but for larger values, no bound modes exist. We also let the angle between the strips to vary and found that the number of the bound modes highly depends on the opening angle of the outlets in the Y-shaped waveguide. For the Z- and C-shaped waveguides, we let the height of the waveguide change. We saw that there may appear two bound states at most. Moreover, for the C-shaped waveguide, the first is monotone increasing as a function of height and the second eigenvalue is monotone decreasing. For the Z-shaped waveguide, we show that the lowest eigenvalue as a function of the height is not monotone. / Tiivistelmä Tässä väitöskirjassa tutkitaan kvanttiaaltojohteisiin liittyvää ominaisarvo-ongelmaa. Kvanttiaaltojohteessa aallon eteneminen on rajoitettu tiettyyn suuntaan, ja johde on poikittaissuunnassa nanokokoluokkaa. Kvanttiaaltojohteiden tutkimus on tärkeä osa nykyistä puolijohdeteknologiaa. Tutkimuksessamme olemme keskittyneet kaksi- ja kolmiulotteisiin aaltojohteisiin, jotka geometrialtaan muistuttavat Y-, Z- tai C-kirjainta. Haluamme tietää millaisissa tilanteissa elektronin liike aaltojohteessa estyy. Yleisesti tiedetään, että aaltojohteessa olevat pullistumat ja mutkat johtavat niin sanottuun sidottuun tilaan, ts. tilanteeseen että tietyllä taajuudella tai energiatasolla oleva partikkeli jää lokalisoituun tilaan. Aaltojohde rakentuu puhtaasta kiderakennemateriaalista, joka on kokoluokaltaan pieni poikittaissuunnassa, niin että elektronin liikettä voidaan kuvata vapaan elektronin mallilla Schrödingerin yhtälössä, jossa elektronilla on effektiivinen massa. Tämä johtaa Laplace-operaattorin ominaisarvo-ongelmaan, reunaehtoina on aaltojohteille käytetty Dirichlet nollareuna-arvoja. Tässä väitöstutkimuksessa on tutkittu kolmea erityyppistä aaltojohdetta, joiden geometriaa voidaan kuvata kirjainten Y, C ja Z avulla. Jokaisessa tapauksessa on tutkittu spektristä erityisesti diskreettiä osaa, ja erityisesti mahdollisia muutoksia diskreetissä spektrissä geometristen parametrien muuttuessa. Diskreetin spektrin tutkimiseen on käytetty variaatiomenetelmiä, asymptoottista analyysiä sekä numeerisista menetelmistä elementtimenetelmää. Geometrialtaan kirjainta Y muistuttava aaltojohde koostuu kolmesta haarasta, joista yhden leveyden annetaan varioida. Tällöin voidaan löytää kriittinen raja, siten että jalan leveyden ollessa tätä rajaa pienempi on diskreetti spektri epätyhjä kun taas leveyden ollessa kriittistä rajaa suurempi, diskreetti spektri on tyhjä. Toisessa tapauksessa jalan leveydet pidetään samana, mutta annetaan kulman kahden haaran välillä muuttua. Voidaan nähdä, että diskreetissä spektrissä olevien ominaisarvojen lukumäärä riippuu aaltojohteen kulmasta siten että mitä pienempi kulma kahden haaran välillä, sitä enemmän ominaisarvoja on diskreetissä spektrissä. Vastaavasti Z- ja C- aaltojohteissa, aaltojohteen korkeutta säädellään. Havaitaan, että korkeuden kasvaessa, voi aaltojohteessa esiintyä korkeintaan kaksi ominaisarvoa diskreetissä spektrissä. Lisäksi C-aaltojohteen ensimmäisen ominaisarvon voidaan havaita olevan kasvava aaltojohteen korkeuden funktiona kun taas toinen ominaisarvoista on vähenevä. Toisaalta taas Z-aaltojohteen pienin ominaisarvo korkeuden funktiona ei ole monotoninen.

This work presents the development of an in-plane vertical micro-coaxial probe using bulk micromachining technique for high frequency material characterization. The coaxial probe was fabricated in a silicon substrate by standard photolithography and a deep reactive ion etching (DRIE) technique. The through-hole structure in the form of a coaxial probe was etched and metalized with a diluted silver paste. A co-planar waveguide configuration was integrated with the design to characterize the probe. The electrical and RF characteristics of the coaxial probe were determined by simulating the probe design in Ansoft’s High Frequency Structure Simulator (HFSS). The reflection coefficient and transducer gain performance of the probe was measured up to 65 GHz using a vector network analyzer (VNA). The probe demonstrated excellent results over a wide frequency band, indicating its ability to integrate with millimeter wave packaging systems as well as characterize unknown materials at high frequencies. The probe was then placed in contact with 3 materials where their unknown permittivities were determined. To accomplish this, the coaxial probe was placed in contact with the material under test and electromagnetic waves were directed to the surface using the VNA, where its reflection coefficient was then determined over a wide frequency band from dc-to -65GHz. Next, the permittivity of each material was deduced from its measured reflection coefficients using a cross ratio invariance coding technique. The permittivity results obtained when measuring the reflection coefficient data were compared to simulated permittivity results and agreed well. These results validate the use of the micro-coaxial probe to characterize the permittivity of unknown materials at high frequencies up to 65GHz.

Microstructure manipulation is a fundamental process to the study of biology and medicine, as well as to advance micro- and nano-system applications. Manipulation of microstructures has been achieved through various microgripper devices developed recently, which lead to advances in micromachine assembly, and single cell manipulation, among others. Only two kinds of integrated feedback have been demonstrated so far, force sensing and optical binary feedback. As a result, the physical, mechanical, optical, and chemical information about the microstructure under study must be extracted from macroscopic instrumentation, such as confocal fluorescence microscopy and Raman spectroscopy. In this research work, novel Micro-Opto-Electro-Mechanical-System (MOEMS) microgrippers are presented. These devices utilize flexible optical waveguides as gripping arms, which provide the physical means for grasping a microobject, while simultaneously enabling light to be delivered and collected. This unique capability allows extensive optical characterization of the structure being held such as transmission, reflection, or fluorescence. The microgrippers require external actuation which was accomplished by two methods: initially with a micrometer screw, and later with a piezoelectric actuator. Thanks to a novel actuation mechanism, the “fishbone”, the gripping facets remain parallel within 1 degree. The design, simulation, fabrication, and characterization are systematically presented. The devices mechanical operation was verified by means of 3D finite element analysis simulations. Also, the optical performance and losses were simulated by the 3D-to-2D effective index (finite difference time domain FDTD) method as well as 3D Beam Propagation Method (3D-BPM). The microgrippers were designed to manipulate structures from submicron dimensions up to approximately 100 µm. The devices were implemented in SU-8 due to its suitable optical and mechanical properties. This work demonstrates two practical applications: the manipulation of single SKOV-3 human ovarian carcinoma cells, and the detection and identification of microparts tagged with a fluorescent “barcode” implemented with quantum dots. The novel devices presented open up new possibilities in the field of micromanipulation at the microscale, scalable to the nano-domain.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第22244号 / 理博第4558号 / 新制||理||1655(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 阪部 周二, 准教授 橋田 昌樹, 教授 鶴 剛 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

This thesis is focused on a wireless link operating in 60 GHz frequency band. In this band, the attenuation due to resonance of oxygen is high. Thanks to this property, we are able to ensure a proper insulation of communication links working in two close bands. The document compares commercially available modules of offered by different manufacturers for the operation in this band. The design, the simulation and the fabrication of a antenna and its feeder are described in the next part of the thesis. The system is fabricated using a SIW technology.

abstract: Presented is a design approach and test of a novel compact waveguide that demonstrated the outer dimensions of a rectangular waveguide through the introduction of parallel raised strips, or flanges, which run the length of the rectangular waveguide along the direction of wave propagation. A 10GHz waveguide was created with outer dimensions of a=9.0mm and b=3.6mm compared to a WR-90 rectangular waveguide with outer dimensions of a=22.86mm and b=10.16mm which the area is over 7 times the area. The first operating bandwidth for a hollow waveguide of dimensions a=9.0mm and b=3.6mm starts at 16.6GHz a 40% reduction in cutoff frequency. The prototyped and tested compact waveguide demonstrated an operating close to the predicted 2GHz with predicted vs measured injection loss generally within 0.25dB and an overall measured injection loss of approximately 4.67dB/m within the operating bandwidth. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2019

Phased array antennas, capable of controlling the direction of their radiated beam, are demanded by many conventional as well as modern systems. Applications such as automotive collision avoidance radar, inter-satellite communication links and future man-portable satellite communication on move services require reconfigurable beam systems with stress on mobility and cost effectiveness. Microwave phase shifters are key components of phased antenna arrays. A phase shifter is a device that controls the phase of the signal passing through it. Among the technologies used to realize this device, traditional ferrite waveguide phase shifters offer the best performance. However, they are bulky and difficult to integrate with other system components. Recently, ferrite material has been introduced in Low Temperature Co-fired Ceramic (LTCC) multilayer packaging technology. This enables the integration of ferrite based components with other microwave circuitry in a compact, light-weight and mass producible package. Additionally, the recent concept of Substrate Integrated Waveguide (SIW) allowed realization of synthesized rectangular waveguide-like structures in planar and multilayer substrates. These SIW structures have been shown to maintain the merits of conventional rectangular waveguides such as low loss and high power handling capabilities while being planar and easily integrable with other components. Implementing SIW structures inside a multilayer ferrite LTCC package enables monolithic integration of phase shifters and phased arrays representing a true System on Package (SoP) solution. It is the objective of this thesis to pursue realizing efficient integrated phase shifters and phased arrays combining the above mentioned technologies, namely Ferrite LTCC and SIW. In this work, a novel SIW phase shifter in ferrite LTCC package is designed, fabricated and tested. The device is able to operate reciprocally as well as non-reciprocally. Demonstrating a measured maximum reciprocal phase shift of 132o and maximum non-reciprocal shift of 118o at 12 GHz. Additionally a slotted SIW antenna is designed and integrated with the phase shifter in an array format, demonstrating a beam scanning of ± 15o. The design is highly suitable for mobile automotive radars and satellite communications systems.

No description available.