Dissertations / Theses on the topic 'All-dielectric'

This thesis reports on my research efforts towards all-dielectric metamaterials with reconfigurable functionalities: • I have reported the first optomechanical nonlinear dielectric metamaterial. I have shown that such metamaterials provide extremely large optomechanical nonlinearities at near infrared, operating at intensities of only a few μW per unit cell and modulation frequencies as high as 152 MHz, thereby offering a path to fast, compact, and energy efficient all-optical metadevices. • I have experimentally demonstrated the first all-dielectric electro-optical nanomechanical modulator based on all-dielectric nanomembrane metamaterial. Furthermore, I have shown the dynamical control of optical properties of this device, with modulation frequency up to 7 MHz. I have also establish an encapsulation technique where any nano-membrane can be embedded within a fiber setup with electrical feedthroughs and pressure control. • I have studied for first time the optical properties of Diamond nano-membrane metamaterials. Diamond membranes after nanostructuring with Focus Ion Beam, present broadband, polarization-independent absorption that can be used as efficient coherent absorbers for optical pulses as short as 6 fs. This novel class of metamaterials have been used for coherent modulation with modulation contrast up to 40% at optical fluences of few nJ/cm2 across the visible spectrum. • I have reported the first optically-switchable, all-chalcogenide phase-change metamaterial. Germanium antimony telluride alloys (GST) after nanostructuring subwavelength-thickness films of GST present high-quality resonances that are spectrally shifted by laser-induced structural transitions, providing reflectivity and transmission switching contrast ratios of up to 5:1 (7 dB) at near-infrared wavelengths selected by design, or strong colour contrast in visible due to its plasmonic nature. • This work has introduced dielectric nano-membrane metamaterials, as a platform to provide optically switchable, nonlinear, reconfigurable responses. Due to nanomechanical actuation based on optical/electromagnetic forces, coherent modulation based on the diamond absorbers and phase change media of Chalcogenide glasses.

La méta-optique non linéaire tout diélectrique suscite un vif intérêt, grâce à la faisabilité de nanostructures à contraste élevé et indice de réfraction disponible avec la lithographie à semi-conducteurs. Alors que des effets nonlinéaires au troisième ordre ont été rapportés dans les nanoantennes silicium sur isolant, la plate-forme AlGaAs-sur-isolant a récemment permis la démonstration de la génération de la seconde harmonique, dû à la noncentrosymétrie de ce matériel. Cette thèse illustre notre activité récente sur les nanoantennes non linéaires AlGaAs-sur-AlOx, où AlOx est obtenu par attaque chimique sélective par voie humide d'une couche épitaxiale d'AlGaAs riche en aluminium d'une épaisseur de quelques micromètres. Un tel substrat à faible indice de réfraction permet de découpler efficacement les modes nanoantenna de la tranche de GaAs (100) sous-jacent. La thèse présente d'abord les méthodes numériques, expérimentales et technologiques utilisées. Une analyse des résultats obtenus dans la génération de signaux non linéaires dans des nanoantennes simples et dans des structures complexes est ensuite présentée. Tous nos résultats expérimentaux ouvrent la voie à la génération et à la manipulation de signaux non linéaires à l'échelle nanométrique et pointent vers des applications telles que l'holographie non linéaire, la goniométrie sans fond et la vision nocturne
All-dielectric nonlinear meta-optics is attracting a great deal of interest thanks to the feasibility of high refractive-index contrast nanostructures available with semiconductor lithography. While third order nonlinear effects have been reported in silicon-on-insulator nanoantennas, the AlGaAs-on-insulator platform has recently enabled the demonstration of second harmonic generation, owing to the non-centrosymmetry of this material. This PhD thesis illustrates our recent activity on AlGaAs-on-AlOx nonlinear nanoantennas, where AlOx is obtained from selective wet etching of micrometer-thick aluminium-rich AlGaAs epitaxial layer. Such a low refractive index substrate allows to effectively decouple the nanoantenna modes from the underlying GaAs (100) wafer. The thesis first introduces the numerical, experimental and technological methods employed. Afterwards, a review of the results obtained in nonlinear signal generation in single nanoantennas and in complex structures is given. All our experimental results pave the way towards nonlinear signal generation and manipulation at the nanoscale, and point towards applications such as nonlinear holography, background-free goniometry and night vision

One of the great challenges in optics is to break the diffraction limit to achieve optical superresolution for applications in imaging, sensing, manufacturing and characterization. In recent years we witnessed a number of exciting developments in this field, including for example super-resolution fluorescent microscopy, negative-index metamaterial superlens and superoscillation lens. However, none of them can perform white-light super-resolution imaging until the development of microsphere nanoscopy technique, which was pioneered by the current PhD’s research group. The microscope nanoscopy technique was developed based on all-dielectric microsphere superlens which is fundamentally different from metal-based superlenses. In this research, we aim to significantly advance the technology by: (1) increasing superlens resolution to sub- 50 nm scale and (2) improving superlens usability and demonstrate application in wider context including lab-on-chip devices. Our longer-term vision is to bring the all-dielectric superlens technology to market so that each microscope user can have superlens in hand for their daily examination of nanoscale objects including viruses. To improve the superlens resolution, a systematic theoretical study was first carried out on the optical properties of dielectric microsphere superlens. New approaches were proposed to obtain precise control of the focusing properties of the microsphere lens. Using pupil mask engineering and two-material composite superlens design, one can precisely control the focusing properties of the lens and effectively surpass the diffraction limit λ/2n. To further improve the resolution, we incorporated the metamaterial concept in our superlens design. A new all-dielectric nanoparticle metamaterial superlens design was proposed. This is realized by 3D stacking of high-index nanoparticles to form a micro-sized particle lens. This man-made superlens has unusual optical properties not found in nature: highly effective conversion of evanescent wave to propagating wave for unprecedented optical super-resolution. By using 15 nm TiO2 nanoparticles as building blocks, the fabricated 3D all-dielectric metamaterial-based solid immersion lens (mSIL) can produce a sharp image with a super-resolution of at least 45 nm under a white-light optical microscope, significantly exceeding the classical diffraction limit and previous near-field imaging techniques. In additional to mSIL where only one kind of nanoparticle was used, we also studied twoVII nanomaterial hybrid system. High-quality microspheres consisting of ZrO2/polystyrene elements were synthesised and studied. We show precise tuning of the refractive index of microspheres can effectively enhance the imaging resolution and quality. To increase superlens usability and application scope, we proposed and demonstrated a new microscope objective lens that features a two times resolution improvement over conventional objective. This is accomplished by integrating a conventional microscope objective lens with a superlensing microsphere lens with a customised lens adaptor. The new objective lens was successfully demonstrated for label-free super-resolution static and scanning imaging of 100 nm features in engineering and biological samples. In an effort to reduce superlens technology entrance barrier, we studied several spider silks as naturally occurring optical superlens. These spider silks are transparent in nature and have micron-scale cylinder structure. They can distinctly resolve λ/6 features with a large field-of-view under a conventional white-light microscope. This discovery opens a new door to develop biology-based optical systems and has enriched the superlens category. Because microsphere superlenses are small in size, their application can be extended to lab-on-chip device. In this thesis, microsphere superlens was introduced to a microfluidic channel to build an on-chip microfluidic superlensing device for real-time high-resolution imaging of biological objects. Several biological samples with different features in size, transparency, low contrast and strong mobility have been visualised. This integrated device provides a new way to allow researchers to directly visualise details of biological specimens in real-time under a conventional white light microscope. The work carried out in this research has significantly improved the microsphere superlens technology which opens the door for commercial exploitation.

This thesis describes my work on manufacturing of all dielectric polymer/ceramic composites for electromagnetic property customisation at microwave frequencies. Electromagnetic wave manipulation can be achieved with the help of transformation optics concept and metamaterials with desired permittivity and permeability properties. The use of all-dielectric metamaterials, in particular, offers a novel solution to broadband, low loss microwave devices. In this work, polymer/ceramic composites were studied to provide materials with a wide range of permittivity that can be customised precisely by optimised manufacturing routes. Thermoplastic perfluoroalkoxy (PFA) and thermoset epoxy were mainly used as polymer matrices and ferroelectric powders such as barium titanate used as ceramic fillers. Different composite types were fabricated by spraying, casting and 3D printing, with each manufacturing method carefully studied to produce stable and uniform composite quality. The microstrcutures of these composites were examined by microtomy and SEM and the dielectric properties were assessed by impedance and waveguide measurements for difference microwave frequency ranges. Controllable dielectric constants from 3 to 18 with high accuracy in epoxy/BT composites were achieved at 12 - 18 GHz. These composites were then used to fabricate advanced microwave devices such as the power divider lens to demonstrate my capability of permittivity customisation. Simulations for these advanced applications were done in Comsol Multiphysics and were compared to the experimental results.

Cavity polaritons are quasiparticles formed when a photon con ned within a cavity interacts with an elementary excitation in a semiconductor that is called exciton. Under the right conditions, cavity polaritons form a macroscopic condensate in the ground state. This condensate decays through the cavity mirrors, thus providing coherent light-emission: a phenomenon termed polariton lasing. The threshold for polariton lasing can be signi cantly lower than that required for conventional lasing. Large exciton binding energies are an essential requirement to obtain polariton lasing at room temperature. Group III nitrides and ZnO are the only inorganic semiconductors possessing Wannier-Mott exciton binding energies above 25 meV, the room-temperature thermal energy. In contrast, Frenkel excitons in organic semiconductors possess binding energies of 1 eV and are thus highly stable at room temperature. This thesis consists of two parts. The first part concerns the fabrication and optical characterisation of samples consisting of an ultra-smooth GaN membrane encapsulated in an all-dielectric (SiO2/Ta2O5) distributed Bragg reflector (DBR) microcavity. By utilising the selective photo-electro-chemical (PEC) etching of an InGaN sacri cial layer, GaN membranes 200 nm thick are produced and introduced between DBRs. The second part is devoted to the demonstration of a room-temperature organic polariton condensate. The studied samples consist of a thermally evaporated 2,7-bis[9,9-di(4-methylphenyl)-fluoren-2-yl]-9,9-di(4-methylphenyl) fluorene (TDAF) thin film enclosed within an all-dielectric microcavity, consisting of SiO2 and Ta2O5 pairs. In both GaN and organic systems, the strong coupling for various detunings is demonstrated by performing angle-resolved reflectivity and photoluminescence (PL) measurements. On reaching threshold, the nonlinear increase in the PL is blueshifted with respect to low power emission, and is accompanied by a simultaneous reduction in the linewidth, marking the onset of polariton lasing at room-temperature. In the organic microcavities particularly, the condensate formed above threshold is linearly polarised and exhibits o -diagonal long-range order with a spatial coherence that is dependent on the pump shape. Moreover, the ambipolar electrical characteristics of this organic semiconductor and the high electron mobility of GaN suggest both materials as promising candidates for direct electrical injection.

Metasurfaces which emerged as two-dimensional counterparts of metamaterials, facilitate the realization of arbitrary phase distributions using large arrays with subwavelength and ultra-thin features. Even if metasurfaces are ultra-thin, they still effectively manipulate the phase, amplitude, and polarization of light in transmission or reflection mode. In contrast, conventional optical components are bulky, and they lose their functionality at sub-wavelength scales, which requires conceptually new types of nanoscale optical devices. On the other hand, as the optical systems shrink in size day by day, conventional bulky optical components will have tighter alignment and fabrication tolerances. Since metasurfaces can be fabricated lithographically, alignment can be done during lithographic fabrication, thus eliminating the need for post-fabrication alignments. In this work, various types of metasurface applications are thoroughly investigated for robust wavefront engineering with enhanced characteristics in terms of broad bandwidth, high efficiency and active tunability, while beneficial for application. Plasmonic metasurfaces are not compatible with the CMOS process flow, and, additionally their high absorption and ohmic loss is problematic in transmission based applications. Dielectric metasurfaces, however, offer a strong magnetic response at optical frequencies, and thus they can offer great opportunities for interacting not only with the electric component of a light field, but also with its magnetic component. They show great potential to enable practical device functionalities at optical frequencies, which motivates us to explore them one step further on wavefront engineering and imaging sensor platforms. Therefore, we proposed an efficient ultra-thin flat metalens at near-infrared regime constituted by silicon nanodisks which can support both electric and magnetic dipolar Mie-type resonances. These two dipole resonances can be overlapped at the same frequency by varying the geometric parameters of silicon nanodisks. Having two resonance mechanisms at the same frequency allows us to achieve full (0-2π) phase shift on the transmitted beam. To enable the miniaturization of pixel size for achieving high-resolution, planar, compact-size focal plane arrays (FPAs), we also present and explore the metasurface lens array-based FPAs. The investigated dielectric metasurface lens arrays achieved high focusing efficiency with superior optical crosstalk performance. We see a magnificent application prospect for metasurfaces in enhancing the fill factor and reducing the pixel size of FPAs and CCD, CMOS imaging sensors as well. Moreover, it is of paramount importance to design metasurfaces possessing tunable properties. Thus, we also propose a tunable beam steering device by combining phase manipulating metasurfaces concept and liquid crystals. Tunability feature is implemented by nematic liquid crystals infiltrated into nano holes in SiO2. Using electrically tunable nematic liquid crystals, dynamic beam steering is achieved

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 103-106).
Gradient index (GRIN) materials offer the most general manipulation over wave fields of light compared to conventional refractive optics, where the light is deflected by the curved surface. The creative way to implementing GRIN optics is to construct a subwavelength structure with the electromagnetic characteristics that are unavailable via the natural material. This artificial GRIN structure also known as "metamaterial" can be classified into two general categories: film and slab GRIN optics, depending on the propagation direction of light penetrating through or propagating along the metamaterial. In this dissertation, two different purposes of all-dielectric GRIN optics on (1) film: light extraction enhancement of the scintillator; (2) slab: aberration-free focusing using Lüneburg lens, are both investigated. The scintillator made by ceramics like Lutetium Yttrium Orthosilicate (LYSO) possesses higher index of refraction at 1.82 than the surrounding environment, which causes extraction loss due to index mismatching and total internal reflection (TIR) from scintillator to photodetector. A hybrid structure including two-dimensional photonic slab covered by the nanocone structure on the top was devised to recycle the energy loss from TIR and to create an index-matching layer in between. Design parameters of the hybrid structure were optimized by the simulation based on rigorous coupled-wave analysis, and the fabrication of hybrid structure was patterned by nanospheres (for nanocone structure) and laser interference (for photonic slab) lithography, respectively. Reactive ion etching (RIE) facilitated pattern transfer after two separate lithography processes. Finally, the characterization of nanostructured scintillator was performed with the ionizing source. The rest of this research focuses on the implementation of the slab GRIN optics: Nanostructured Lüneburg lens. The Lineburg lens is an aberration-free lens that can perfectly focus light on the opposite edge of the lens area, and such property can be used for light coupling from fiber to waveguide in the Silicon photonics. We designed the nanostructured Lineburg lens on the silicon-on-insulator substrate using effective index of refraction computed by photonic band theory, and the fabrication was carried out by the e-beam lithography and RIE process. The device characterized by near-field scanning optical microscopy exhibited the single focusing behavior under fundamental mode illumination via the intensity map over the lens region. In addition, the bi-foci phenomenon under higher order mode illumination was also revealed in the finite difference time domain simulation, and the ray picture for explaining the bi-foci was also included using Wigner distribution function and Hamiltonian ray-tracings.
by Chih-Hung Hsieh.
Ph. D.

The successful implementation of nonlinear devices, for example for all-optical switching, depends critically on the availability of appropriate nonlinear optical materials. Most of the currently used methods to measure optical nonlinearities of materials are either indirect or inadequate for separating the fast electronic effects from slow thermo-optic processes. The motivation of this Ph.D. research was to develop a direct and accurate measurement method to evaluate the nonlinear optical properties of various, recently available waveguide materials for all-optical switching applications. A pulse modulated Mach-Zehnder scanning interferometer was built and revised to obtain a resolution of π/100 for nonlinear phase measurements. The evolution of this instrument included the development of single pulse extraction from a mode-locked pulse train, intensity modulation of single pulses, numerical Hilbert transformation of fringe data set, mode profile calculation inside waveguides with a numerical Fourier method, and a careful study of pulse breakup effect associated with instantaneous nonlinear phase shift. Electronic and thermal nonlinear refractive indices of various newly developed materials, especially DANS channel waveguides, DAN single crystal fibers, LiNbO₃ channel waveguide were examined with this method at the 1.32 μm wavelength. For the DAN single crystal cored fibers, the physical origin of the exceptionally large nonlinear phase changes in single crystal fibers was identified to be the cascading of two second order nonlinear processes. In the LiNbO₃ waveguide, cascaded nonlinear phase changes near the second harmonic phase matching temperature were demonstrated for the first time. Based on the results above, single crystal organic fibers appear very promising for ultrafast all optical switching applications. This demonstrates that the interferometric measurement method based on a scanning pulse modulated Mach-Zehnder Interferometer has proven to be one of the best methods for identifying nonlinear materials for all-optical switching applications at the 1.32 μm communications wavelength.

The operational life of all-dielectric self supporting (ADSS) optical fibre cables installed on high voltage over-head power transmission lines is limited by sheath degradation caused by induced electrical activity on the cable's surface. The work presented in this thesis describes research completed to quantify this degradation. This has resulted in a novel analysis method being developed and used to associate product testing with field trial results. The analysis is based on evaluating the magnitude of recorded electrical activity and fitting an appropriate distribution to the data to describe relative electrical arcing power. This innovation was possible due to the completion of a comprehensive review of the theories dealing with the generation of the electrical activity, followed by a detailed analysis. Where appropriate, worked examples are given in the thesis to demonstrate these theories. As a result of this work three proposals have been made to simplify future analyses. They are: approximating the relevant variables to span related polynomial functions, relating capacitive coupling to the space potential, and the superposition of assumed functions. The work is supported by results presented of extensive practical testing and simulations carried out by the author. These include analyses of the resulting cable damage, some of which has not been discriminated between in previous work. The completed analysis of tested products has also identified, previously not quantified, degradation accelerants. The work classifies these accelerants into extrinsic installation and intrinsic product factors. The thesis presents and reviews the implication of the electrical degradation resistance of sheaths applied to slotted-core and advance multi-loose tube (MLT) optical fibre cable designs. This has lead to the evaluation of three generations of sheath technology, which varied from low smoke compound technology, through to bimodal polyethylene. The work also identifies specific methods to limit risk to products. They include the use of pre-blended materials and the need to assure both sheath surface finish quality and cable longitudinal water blocking. Finally, the thesis summarises the development of new and previously investigated proposed degradation mitigation systems. Selected possible solutions were then evaluated using tests and analysis methods developed by the author, and compared with those of other notable works. This has resulted in the filing of two patents. As a result of this research a solution has been trialed and proposed to the collaborating company. This will allow optical fibre cable to be installed in high potential fields for the prescribed lifetime, overcoming previous limitations.

In this thesis, new all-printed capacitors are developed for the applications of energy storage, filter, and resonant circuits by using new dielectric material and an advanced technology. The innovative devices provide satisficing electrical performances with high breakdown voltages and capacitance densities. The main body of this thesis is divided in three parts. The first part is to introduce the fundamental background of printing technologies, electrical capacitors and printable materials. Among all the printing technologies, direct writing family is the most advantageous in the small-scale and fast production of printed electronics due to the properties of masterless processing, digital control, and print-on-demand. Both inkjet printing and ultrasonic fluid dispensing applied in this work are grouped into the direct writing family. A cross-linkable dielectric material poly(methyl methacrylate)84/(4-benzoylphenyl methacrylate)16 [P(MMA84/BPMA16)] exhibits the optimized chemical and mechanical stabilities in comparison with uncross-linked poly(methyl methacrylate) (PMMA). Poly(vinylidene fluoride-co-trifluoro ethylene) [P(VDF-TrFE)] exhibits a high dielectric constant of 16. The great advantages of both polymeric dielectrics make them ideal for printed electronics. The second part is devoted to the preparation of printed thin-film capacitors by providing four different layouts and architectures for multiple electronic applications. The printing setup, process setting and steps are summarized in detail. The following part which is the major content of this thesis is divided into two aspects: in the first aspect, the intriguing new form of continuous solution dispensing technology, ultrasonic fluid dispensing, is demonstrated as an alternative printing technology for the commonly applied ones. In comparison with the widely-used inkjet printing, continuous solution dispensing is the most advantageous in thin-film capacitor processing with metal nanoparticle and polymer dielectric inks. It enables precise pattern transfers with low surface roughness, small feature size (as small as 5 μm), and accurate positioning (5 μm resolution). Most importantly, problems due to discrete droplets and nozzle clogging in inkjet printing are avoided in continuous solution dispensing. All the inks applied for printed capacitors in this work are printed successfully with this innovating technology. Direct printing on demand and rapid switching among different inks are some other attributes of this printing technology that enable high throughput. The second aspect of this part is to characterize and evaluate the fabricated capacitors. The measured values include capacitor dimension, dielectric strength, capacitance density, energy density, charge/discharge behavior and so on. In summary, this work provides not only the use of the advantageous materials P(MMA84/BPMA16) and P(VDF-TrFE) in high-performance capacitors, but also paves the way of developing thin-film capacitors with a new continuous solution dispensing technology which makes the low-cost and high-quality manufacture of printed devices possible.

This thesis is focused on assessing the impact of retrofitting dielectric All Dielectric Self-Supporting Cable (ADSS) to existing MV overhead line. This type of optical cable is a means of future strengthening of the communication infrastructure of the distribution network. However, its mechanical properties are significantly different from the properties ACSR cable, due to which its installation can be problematic in terms of meeting the requirements of the PNE 33 3301 standard. In practical part, this work deals with the design of the ADSS installation on the existing MV line and the determination of its impact based on the assessment of the results of this design.

All-dielectric metasurfaces have received significant attention in the past years, and have been established as a platform for efficient manipulation of optical beams. Advances in the design and fabrication of such dielectric metasurfaces have led to the development of several ultra-thin optical metadevices, including flat lenses, beam converters, deflectors and holograms. Composed of periodic or aperiodic lattices of dielectric nanoparticles, metasurfaces exhibit low absorption in the infrared and visible spectral ranges. Low losses allow nanoparticles to exhibit Mie-type resonances with a higher quality-factor in comparison to their plasmonic counterparts. Furthermore, Mie-type resonances in dielectric nanoparticles offer two independent families of resonant modes - electric and magnetic. The far-field interference of these two types of resonant modes leads to fundamentally new effects, such as unidirectional scattering, unconventional reflection behaviour associated with the generalised Brewster effect and near-unity transmission in the so-called Huygens' regime. Operating in the Huygens' regime of the dielectric metasurfaces enables the combination of near-unity transmission together with a full range of phase modulation, thus being the key to enabling functional dielectric metasurfaces with nearly 100% efficiency. Most functional dielectric metasurfaces to date are based on static designs, defined through geometrical parameters, such as nanoparticle shape, size, and array layout. However, in many applications, it is crucial to enable dynamic tunability of the device functionality with time. For example, the focal distance of a camera lens needs to be changed when taking pictures of objects at different distances; the position of the ranging beam in a LIDAR (light imaging, detection, and ranging) for driverless vehicles needs to scan different directions. Therefore, implementing dynamic control} over the response of the metasurfaces is of paramount importance for their practical implementation. In this thesis, I discuss possible ways to achieve tunability from dielectric metasurfaces. At first, I consider existing methods, their pros and cons, as well as possible applications. Further, I offer several methods that I developed and investigated, both theoretically and experimentally. Namely, I describe tuning by changing the properties of resonator material, where I utilise a thermo-optic effect to control the refractive index of resonator particles and consequently the optical response of metasurfaces. Next, I consider tuning by changing the properties of surrounding material, first theoretically, and later demonstrating experimental realisation of this concept using a liquid crystal as a tuning medium. Finally, I describe two tunable metadevices: one, for switching a beam deflection, and second, for active tuning of spontaneous emission.

碩士
輔仁大學
物理研究所
83
The anticounterfeting ink can be produced by mixing anticounterfeting thin film flakes and ink. Using the optical interference properties of anticounterfeting thin film, we can see different color when viewed from different angles. The roles of the ink play the protector of the anticounterfeting flakes and transferred the optical coating to the document surface. The proposes of the thesis are the study and fabrication of all- dielectric anticounterfeting ink. Two types of designs, one have reflected-type and transmitted-type and the other have transmitted-type all-dielectric coatings, have been theoretically considered, and chosen the optimized designs for the experimental fabrication. The anticounterfeting thin films have been coating on two different water-soluble substrates and we used cerium oxide and magnesium fluoride as the material of coating. These results of experiments are closed to the theoretical design. Finally, the fabrications of anticounterfeting thin film have been reached. The effect of paints made lead to results in good agreement with theoretical design.

[ES] La revolución posibilitada por las aplicaciones fotónicas durante las últimas décadas ha dejado su impronta en la sociedad tal y como la conocemos actualmente. Ejemplos claros de este impacto están patentes en, por ejemplo, el enorme tráfico de datos generado por el uso de Internet o el empleo extendido de algunas técnicas biomédicas con fines diagnósticos o quirúrgicos, que no podrían entenderse sin el incesante desarrollo de los sistemas ópticos. La necesidad de combinar y miniaturizar estos sistemas para generar funcionalidades más avanzadas dio lugar al nacimiento de los circuitos fotónicos integrados (PICs), que es donde esta tesis comenzó a tomar forma. En este sentido, observamos limitaciones en términos de flexibilidad o reconfigurabilidad inherentes a la naturaleza guiada de la mayoría de los PICs realizados hasta el momento. En el caso de circuitos plasmónicos, observamos también limitaciones por las pérdidas que tienen las guías metálicas a altas frecuencias. La inclusión de estructuras inalámbricas (basadas principalmente en nanoantenas plasmónicas) en la capa fotónica surgió para mitigar estas pérdidas, abriendo también nuevas vías de investigación. Sin embargo, estos dispositivos aún presentaban rendimientos muy pobres como elementos puramente radiantes en el régimen de campo lejano. Para superar estas deficiencias, en este trabajo, introdujimos un enfoque novedoso en el desarrollo de dispositivos inalámbricos en la nanoescala, que dio forma a lo que llamamos on-chip wireless silicon photonics. Este nuevo concepto se apoyó en el uso de nanoantenas de silicio compatibles con procesos CMOS, que constituyen las estructuras clave que posibilitan un vasto catálogo de aplicaciones en redes fotónicas de comunicación o en sensores ultra-integrados, así como para la interconexión de sistemas dieléctricos-plasmónicos avanzados. En el ámbito de las comunicaciones, gracias a las sencillas reglas de diseño para adaptar la directividad de estas nanoantenas a diversas aplicaciones, pudimos demostrar por primera vez transmisiones inalámbricas de datos (mediante el uso de antenas altamente directivas) en redes on-chip reconfigurables o desarrollar dispositivos para generar a voluntad focos electromagnéticos de manera dinámica en espacios bidimensionales (gracias a antenas con una directividad más baja). Por otro lado, en el campo del biosensado, diseñamos y fabricamos un dispositivo lab-on-a-chip para la identificación de micropartículas, basado en el uso de antenas dieléctricas -presentando un rendimiento equiparable a los mejores diseños desarrollados hasta el momento- que incluye el subsistema óptico más compacto demostrado hasta la fecha. Finalmente, fuimos capaces de conectar experimentalmente y de manera eficiente antenas basadas en silicio con estructuras plasmónicas para el desarrollo de nuevas aplicaciones en la nanoescala, aunando las ventajas del on-chip wireles silicon photonics para comunicaciones en chip, conformación dinámica de haces o biosensado con las ventajas de la plasmónica para la manipulación e interacción con luz.
[CAT] La revolució habilitada per les aplicacions fotòniques durant les últimes dècades ha deixat la seua empremta en la societat actual tal com la coneixem. Exemples clars d'aquest impacte estan patents en, per exemple, l'enorme tràfic de dades generat per l'ús d'Internet o d'algunes tècniques biomèdiques amb fins diagnòstics o quirúrgics, que no es podrien entendre sense l'incessant desenvolupament dels sistemes òptics. La necessitat de combinar i miniaturitzar aquests sistemes per produir funcionalitats més avançades va donar lloc al naixement dels circuits fotònics integrats (PICs), que és on aquesta tesi va començar a prendre forma. En aquest sentit, observem limitacions en termes de flexibilitat o reconfigurabilitat inherents a la naturalesa guiada de la majoria dels PICs realitzats fins al moment. En el circuits plasmònics, tenim a mès les limitacions de les elevades pèrdues que les guies metàl·liques tenen a altes freqüències. La inclusió d'estructures sense fil (basades principalment en l'ús de nanoantenes plasmòniques) a la capa fotònica va sorgir per mitigar aquestes pèrdues, obrint també noves vies d'investigació. No obstant això, aquests dispositius encara presentaven rendiments molt pobres com a elements purament radiants en el règim de camp llunyà. Per superar aquestes deficiències, en aquest treball, vam introduir un enfocament innovador en el desenvolupament de dispositius sense fil a la nanoescala, que va donar forma al que anomenem on-chip wireless silicon photonics. Aquest nou concepte està basat en l'ús de nanoantenes de silici compatibles amb processos CMOS, que constitueixen les estructures clau que possibiliten un vast catàleg d'aplicacions en xarxes fotòniques de comunicació o en sensors ultra-integrats, així com per a la interconnexió de sistemes dieléctrics-plasmònics avançats. En l'àmbit de les comunicacions, gràcies a les senzilles regles de disseny per adaptar la directivitat de les antenes a les diverses aplicacions, vam poder demostrar per primera vegada transmissions de dades on-chip (mitjançant l'ús d'antenes altament directives) en xarxes reconfigurables o desenvolupar un dispositiu per generar a voluntat focus electromagnètics de manera dinàmica en espais bidimensionals (gràcies a antenes amb una directivitat més baixa). D'altra banda, en el camp del biosensing, vam dissenyar i fabricar un sensor lab-on-a-chip per a la classificació de micropartícules, basat en l'emprament d'antenes dielèctriques amb un rendiment a l'avantguarda dels millors dispositius de l'estat de l'art, que inclou el subsistema òptic més compacte demostrat fins al moment. Finalment, vam ser capaços de connectar experimentalment i de manera eficient antenes basades en silici amb estructures plasmònics per al desenvolupament de noves aplicacions en la nanoescala, unint els avantatges del on-chip wireless silicon photonics per a comunicacions en xip, conformació dinàmica de feixos o biosensat amb els avantatges de la plasmònica per a la manipulació e interacció amb llum.
[EN] The revolution sparked by photonic applications during the last decades has made its mark in society, as we currently know it. Clear examples of this impact are patent in, for instance, the colossal worldwide data traffic generated by the use of the Internet or the widespread utilization of some biomedical techniques for diagnostic or surgical purposes, which could not be understood without the ceaseless development of optical systems. The necessity of combining and miniaturizing these systems to enable advanced functionalities gave birth to the development of photonic integrated circuits (PICs), which is the main framework within which this thesis began to take shape. Along these lines, we noticed restricted limitations in terms of flexibility or reconfigurability inherent to the wired-based nature of most PIC implementations carried out so far. In the case of plasmonic circuitry, there are additional shortcomings arising from the prohibitive losses of metallic waveguides at very high frequencies. The inclusion of wireless structures (mostly based on plasmonic nanoantennas) at the photonic layer emerged to mitigate these limiting losses, also opening new research avenues. However, these devices still presented poor performances as purely radiating elements in the far-field regime. In order to overcome these lacks, in this work, we introduced a novel version to wireless approaches at the nanoscale in what we called on-chip wireless silicon photonics. This new concept was built upon the use of CMOS-compatible silicon-based nanoantennas, which constitute the key enabling structures of a diverse catalogue of applications in photonic communication networks or ultra-integrated sensors as well as for interfacing advanced dielectric-plasmonic systems. In the scope of communications, thanks to the easiness to tailor the antenna directivity, we were able to experimentally demonstrate on-chip data transmission flows in reconfigurable networks for the first time (by using highly directive antennas) or to develop dynamically tailor-made interference patterns to create focused spots at will on a 2D arrangement (enabled by antennas with a lower directivity). On the other hand, in the field of biosensing, we experimentally implemented a dielectric antenna-based lab-on-a-chip device for microparticle classification with state-of-the-art performance, which included the most compact optical subsystem demonstrated so far. Finally, we were able to efficiently interface silicon-based antennas to plasmonic systems to develop new advanced functionalities at the nanoscale, by putting together the advantages of on-chip wireless silicon photonics for on-chip communications, beam-shaping tailoring or lab-on-a-chip sensing with the advantages of plasmonics for light concentration and manipulation.
Lechago Buendía, S. (2019). All-dielectric nanoantennas enabling on-chip wireless silicon photonics [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/133074
TESIS

碩士
國立臺灣大學
光電工程學研究所
107
Ultrathin, flat optical devices of high performance can be achieved by using metasurfaces that are typically constructed of artificial patterns of subwavelength depth. Metasurfaces can be designed to generate symmetrical wave front where the term, metalenses, has been widely used. In this study, we have introduced a new design principle to develop metalenses without polarization selection instead of using the Pancharatnam-Berry phase design concept. Dielectric materials, GaN and Silicon, have been chosen to realize our metalenses without polarization selection. A commercial software, CST, has been utilized to achieve the phase retardation distribution of the metalenses by simulating the behavior of light-matter interaction for each subwavelength building block. The metalenses have been fabricated by employing the Elionex e-beam 7000 lithography equipment and the ICP system. The polarization insensitivity of the metalenses has been inspected in this study as well. Moreover, it is worth noting that the measured focusing efficiency of our polarization-insensitive metalenses is as high as 90% or higher.

Optical technologies developed throughout history have been exploiting the electric response in matters in order to control light. However, little has been explored for the magnetic response in matter at optical frequencies due to the lack of magnetic materials in this spectral region. Recently, specially engineered materials, namely metamaterials, have been developed to exploit the magnetic responses in matter for light manipulation. In particular, researchers have made use of the optically-induced magnetic responses (OIMRs) generated in metallic nanostructures to achieve optical effects not seen in nature. Such magnetic responses serve as a second channel to control light, providing an alternative and an addition to the electric responses and leading to novel observations and innovative ideas for light manipulation. This creates many opportunities for the development of the next generation nano-optics and nanophotonic devices. Dielectric nanostructures have recently been discovered to also support OIMR, which is useful for applications requiring low loss and simpler fabrication procedures, such as wavefront control and robust nanoscale sensing. In this thesis, I present the study of OIMR in several all-dielectric systems based on silicon nanodisks, namely single, clusters and regular arrays of nanodisks. The study of these systems provides knowledge for and insight into harnessing the OIMRs in dielectric nanostructures for future applications. Chapter 1 provides a comprehensive introduction to OIMR by presenting a historic overview of the topic and the basic concepts involved for high-index dielectric particles. This is followed by a description of the pioneer works on OIMR in dielectric spherical nanoparticles, including the Mie theory and its recent experimental verification. The similarities and differences between the properties of plasmonic and dielectric nanostructures in the context of metamaterials are also described and explained. Finally, the motivation and scope of the thesis is summarized. Chapter 2 describes the experimental methods used that are common to all works presented in this thesis, including the fabrication of silicon nanodisk structures and the linear optical characterization techniques. Chapter 3 presents the fundamental of OIMR in single silicon nanodisk structures, including a theoretical analysis and experimental observation of various resonant modes of single silicon nanodisks, as well as the numerical and experimental results of the Fano resonances observed in the more complex structures of single heptamer oligomers. Chapter 4 focuses on manipulating the OIMR in combination with the electric response to create Huygens' metasurfaces based on silicon nanodisk arrays. Two highly-efficient functional metadevices with polarization independence based on the Huygens' metasurface system are presented, namely a Gaussian-to-vortex beam shaper and a holographic phase plate. Chapter 5 explores the cross-disciplinary area of sensing using silicon nanodisk arrays with OIMRs, including refractive index sensing using Fano resonances and biosensing using the dipolar magnetic resonances where a new detection limit for the Streptavidin protein was achieved. Chatper 6 concludes the thesis and provides an outlook to the research works that can be extended from the results in this thesis.

碩士
國立交通大學
電子工程學系 電子研究所
103
In first two chapters of thesis, basic introduce solar cells and do some literature review. Dielectric mirrors have recently emerged for solar cells due to the advantages of lower cost, lower temperature processing, higher throughput, and zero plasmonic absorption as compared to conventional metallic counterparts. The light trapping mechanism is enhanced by embedded TiO2 scatterers. In chapter 3, used RCWA calculate the reflectance of an ordered and disordered TiO2 array and found the disordered one had much wider reflectance.A randomly distributed TiO2 diffuse reflector will be discussed, and the result is then confirmed by a time domain method using FDTD calculation. In this work, it is shown that scatterers geometry is very important for diffuse reflector. Last part of chapter 3 has been proven that dielectric mirrors can be widely applicable to thin-film and thick wafer-based solar cells to provide for light trapping comparable to conventional metallic back reflectors at their respective optimal geometries. Finally, the near-field angular emission plot of Poynting vectors is conducted, and it further confirms the superior light-scattering property of dielectric mirrors, especially for diffuse medium reflectors, despite the absence of surface plasmon excitation. The experimental results also confirm the high feasibility of dielectric mirrors for photovoltaics.

Over the past few decades, optics-based time-domain spectroscopic systems have significantly promoted the developments of terahertz science and technology. Despite their success in physics, the bulky and costly optical systems are not readily amendable to various applications such as communications, imaging, sensing, and radar. These applications require devices with structural compactness, integrability, and portability. Leveraging both electronic and photonic technologies, terahertz integrated circuits have emerged and gradually bridged the gap between ’concept’ and ’application’. To realise multifunctional terahertz integrated circuits, efficient and broadband platforms able to accommodate various passive and active components are in great demand, while interconnects with low loss, low dispersion, and broad bandwidth are vital. To this end, this thesis focuses on an efficient and broadband terahertz integrated platform based on silicon. Firstly, a class of self-supported substrateless dielectric waveguides are proposed based on the effective medium theory. The effective-mediumclad dielectric waveguides are purely built into a high-resistivity intrinsic float-zone silicon wafer to achieve extremely low loss and low dispersion. The effective medium is realised by periodically perforating the silicon slab with a deep subwavelength spacing, leading to a tailorable effective relative permittivity tensor. Consequently, an additional degree of freedom is granted in this design to manipulate the waveguides’ modal indices and adapt to different guiding scenarios. Through in-depth investigations of various propagation characteristics, the proposed waveguides show a potential to establish a terahertz integrated platform with a high level of design flexibility. Benefiting from the concept of effective medium to create this new waveguide platform, various fundamental building blocks and functional components are proposed including bends, crossings, directional couplers, filters, and polarisation splitters. All these components inherit high efficiency and broad bandwidth, which are much needed for terahertz applications that typically leverage a vast available bandwidth with limited source power. The proposed concepts can benefit terahertz integrated circuits at large, in analogy to the silicon-on-insulator platform for integrated photonics.
Thesis (Ph.D.) -- University of Adelaide,School of Electrical and Electronic Engineering, 2022

Power utilities around the world are now in the practice of installing fiber optic cables on their high voltage transmission networks. These high-speed communication channels can, not only transmit data needed for utility operation, but the unused fiber capacity may also be rented to others for communication. All dielectric self-supporting (ADSS) fiber optic cable appears to be the fiber optic cable most frequently installed by power utilities as it is more economical, has a larger fiber capacity and may be installed on a transmission line without de-energization. When installed however, ADSS fiber optic cable does undergo some degree of degradation caused either by armor rod corona at the towers or dry-band arcing. A comprehensive literature survey regarding both phenomena is presented in this study, as well as current mitigation techniques. Different models that describe the process of dry-band arcing are discussed, including those where an equivalent circuit is used to represent a polluted fiber optic cable in a high voltage environment. An implementation of this model on a MATLAB® based computer program is used to evaluate parameters such as leakage current magnitude, which may be used to predict the possibility of dry-band arcing. This leakage current is also compared to simulated results that were generated using a power system analysis program called Alternate Transients Program (ATP). A finite element package, FEMLAB®, was used to model the experimental system, prior to construction. A single-phase transmission line with an accompanying fiber optic cable was constructed. The leakage current magnitude obtained from this experiment was subsequently compared to those obtained from the simulations. These leakage current comparisons are discussed and explained in view of limitations with the theoretical models and refinements in the experimental techniques employed. The results clearly indicate that physical parameters like pollution severity, system voltage, length of span and the point of attachment of the ADSS fiber optic cable in the tower play a significant role in the determination of leakage currents induced on the outer sheath of the cable. These induced currents result in the formation of 'dry bands', due to joule heating, and this could result in arcing activity that erodes the fiber optic cable.
Thesis (M.Sc.Eng)-University of Natal, Durban, 2003.

碩士
國立交通大學
光電工程研究所
103
Due to the widespread applications of GaN-based material, such as indicators, back lighting, ambient lighting, display, optical storage, optical communication, etc., the GaN-based material has attracted much attention of academia and industry. And then, it is widely investigated and have many remarkable breakthroughs in performance. We have designed a kind of structure which shows both great optical and current confinement, and the oxide-confined structure was successfully applied into the optical pumping vertical-cavity surface-emitting laser. The fact that we obtained the transverse mode in the spectrum proves the abilities of optical and current confinement of this structure. The thesis is focus on the design and fabrication of the study of dielectric type GaN-based vertical-cavity surface-emitting lasers with lateral oxide-confined structure. In order to modify the intrinsic properties of the sapphire substrate, which consist of poor electric and thermal conductivity, and overcome the difficulty in the process of the epitaxial DBR, we used the laser lift-off and wafer bonding technique to fabricate a dielectric type GaN-based VCSEL. After the complicated fabrication process, we observed the existence of transverse modes in the measured spectra. This fact proves that the dielectric confined structure can achieve the two targets of optical and current confinement. Although the device did not achieve the laser action, we measured the spectrum with narrow linewidth. In the future, the devices could achieve the laser action　after we improve the fabrication parameters and make the structure good quality.

碩士
國立雲林科技大學
電子與資訊工程技術研究所
86
The optical filter communication system has certain inherent advantages, which are Wide bandwidth, Small size and weight, Electrical isolation, and Immunity to interference, etc. Therefore, the development of the system is an irresistible force. The purpose of this paper is to investigate the 1.55um/(1.625um or 1.65um ) all-dielectric Fabry-Perot optical interference filters, which are used to eliminate the crosstalk interference between the monitor inspecting wavelength of the fiber observation system and the transmitting wavelength.The design demand is: isolation higher than 35db, insertion loss less than 1db,and the incident angle is 0 degree,using the high refractive material TiO2 and the low refractive material SiO2 to deposit on the glass substrate to form multilayer filters. By the simulation of various multilayer systems and analyzing the influence of layer thickness deviation,we obtain the better structures as below: system A2(1.55um pass/1.65mm stop, isolation 42.4db,insertion loss 0.37db), system A3(1.55um pass/1.65um stop, isolation 36.7db, insertion loss 0.37db), system B2(1.65um pass/1.55um stop, isolation 40. 1db, insertion loss 0.37db), system B3(1.65um pass/1.55um stop, isolation 37.5db, insertion loss 0.37db), system C(1.55um pass/1.625um stop, isolation 40.8db, insertion loss 0.37db), system D(1.625um pass/1.55um stop, isolation 41.6db, insertion loss 0.37db). Finally, the designed structures were deposited by e-gun evaporation, and the measurement matched the simulation very much.

碩士
國立雲林科技大學
電子工程與資訊工程技術研究所
87
The optical fiber communication system has introduced for a period of time. As time goes on, people have more and more requirement for the application such as Internet access, high-quality videoconferencing and multimedia traffic. Dense wavelength division multiplexing（DWDM）is currently the leading technology in transmission links. In DWDM system each channel is related to a different wavelength, channel manipulations and particularly channel selection require optical wavelength selection（i.e., optical filtering）. The purpose of this paper is to investigate narrow band all-dielectric Fabry-Perot optical interference filters, which are used to select required wavelength signal for each channel to transmit and/or receive. Besides, we have investigated the optical characteristics of Ta2O5(92%)/TiO2(8%) film. The design specification of the filter is: bandwidth less than 1nm, transmittance loss less than 1db, and the bandwidth for 30db down less than 2nm, design incident angle is 00. The materials using in design and simulation are following : the high refractive material TiO2 (nH=2.15) and the low refractive material SiO2 (nL=1.435). The substrate and incidence medium is glass(ns=1.52) and air(n0=1) respectively. By the simulation of various multilayer systems and analyzing the influence of layer thickness and refractive index deviation, we obtain the conclusion as below: 1. Except for type IV ( BW30db=2.71nm>2nm) and type VII (BW30db=2.15nm>2nm), the remainder are valid, 2. In order to keep the yield up to acceptable level, the error of film thickness and refractive index must keep as low as 0.03% and 4% respectively.

碩士
國立清華大學
材料科學工程學系
105
A mid-infrared thermal emitter with high emissivity property is proposed and fabri-cated. The thermal emitter is based on all-dielectric architecture where the intrinsic losses of dielectric materials are low. Therefore, we achieve a highly efficient thermal emitter relative to common thermal emitter through a novel approach- the array of low loss die-lectric particles. We characterize the thermal emitter based on all-dielectric architecture via the finite difference time domain method (lumerical). Kirchhoff's law states: For an arbitrary body emitting and absorbing thermal radiation in thermodynamic equilibrium, the emissivity is equal to the absorptivity for the same frequency, same direction, and same polarization. The law holds only when the condition of thermodynamic equilibrium is satisfied. In general, a good absorber is a good emitter. In the design stage, emissivity is regarded as absorptivity, which could be calculated and analyzed in simulation software. In lumerical simulation, absorptance of 97.6% is calculated at the wavelength of 9μm in all-dielectric-based thermal emitter. It is expected that all-dielectric-based thermal emitter possesses some high extent of emissivity. Besides, in numerical simulation result, power absorbed spatial distribution indicates that electromagnetic energy is dissipated within the array of all-dielectric cavities. In the fabrication stage, UV lithography is used to define the pattern of mid-infrared thermal emitter device. It is followed by the deposition of die-lectrics via E-gun evaporation technique. The pattern is formed after the lift-off process. In the measurement setup, the amount of radiant power of all-dielectric-based thermal emitter is measured by the Fourier transform infrared spectroscopy. Then, around 90% emissivity and quality factor of 2.5 are evaluated and calculated in the emission spectrum. Spatial coherence of thermal radiation field is also estimated through the response of emission field over a wide range of incident angles in the simulation.

碩士
國立臺灣大學
光電工程學研究所
106
In this thesis, we develop a parallelized three-dimensional (3-D) finite-difference time-domain (FDTD) numerical simulator by using the message passing interface (MPI) library code in C language. The main purpose of this research is to analyze the scattering properties of all-dielectric cubic nano-antennas, and the mechanism to produce unidirectional scattering. First, the total scattering cross-section and the radiation patterns are calculated. Then we analyze the wavelengths of the dipole resonances and the generalized Kerker''s condition. Moreover, to further increase the directionality of the scattered light, we consider the double nanocubes. Although the directionality of the scattered light can be enhanced by increasing the gap size between the nanocubes, the number and the intensity of the side lobes will be increased at the same time. We also consider a linear chain of nanocubes aligned in z direction, which can enhance the directionality and eliminate the unwanted side lobes simultaneously due to the diffraction grating effect. Finally, the asymmetric nanoparticles which can be utilized to switch the direction of scattered light are studied in detail. Because of the interference between the electric and magnetic dipole resonances stimulated simultaneously in each of the asymmetric nanoparticles, the direction of scattered light can be tuned to either right or left away from the incident wave direction.

碩士
逢甲大學
材料科學與工程學系
105
Nowadays, the scales of integrated circuit along with advances in semiconductor technology and continuing to miniaturization, so it’s imperative to enhance the internal density and chip performance of the components. Recently, the development of the semiconductor industry is focused on reducing the width of metal wires and increasing stacking layers. In order to avoid the problem of RC delay caused by the reducing width and increasing length of the wires, it’s great concern and research on using high conductivity copper wires and low k dielectric layer materials. In this study, we use nanoporous dielectric ultra low k (ULK) materials, named Black DiamondTM III (BD III) to fabricate copper wires by all-electroless plating. We use the techniques, such as: (1) Surface hydroxylation modified. (2) Self-Assembled Monolayer (SAM) deposition. (3) SAM surface functionalization and deprotonation. (4) Catalytic seed fixed. (5) Electroless deposition of Co-alloy barrier layers. (6) Electroless deposition of Cu wires and (7) Co-alloy capping layers deposition by electroless plating on dielectric layers. First, the leakage currents and dielectric constants of the BD III surface hydroxylated by SC-1 solution were measured with the dielectric properties (J-E, C-V), and using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to evaluate the surface bonding changes and hydroxylation effects. According to the results, short-time (10 seconds) modification by SC-1 solution not only achieves hydroxylation effects on BD III, but also causes non-serious damage. After hydroxylation treatment, octadecyltrichlorosilane self-assembled monolayer (OTS-SAM) is deposited on the BD III surface, and the surface is highly hydrophobic. A slight and short-seconds plasma treatment cause the surface becomes hydrophilic. Then, deprotonation by SC-1 solution makes the surface presents negative potential and attracts metal ions, and the metal ions are reduced to the catalytic seed particles fixed on the OTS-SAM for the subsequent electroless Co-alloy barrier layers deposition. Electroless plating Cu wires can easily deposited on Co-alloy surface, according to Co-alloy self-catalytic effect. In order to increase the reliability of Cu wires, this study adopts electroless plating homogeneous metal as capping layers, that is, Cu wires are capped by Co-alloy capping layers. Adding the strong reducing agent into Co-alloy plating solution, Co-alloy capping layers can be precipitated on the Cu wires to achieve a completely capped effect. Finally, a constant current stress is applied to the Cu wires which are uncapped and capped by Co-alloy, to measure the difference in reliability. It is confirmed by the measurement results that Co-alloy capping layers can prolong the electromigration life of Cu and greatly increase the reliability of Cu wires.

The study of nanostructured artificial media for optics has expanded rapidly over the last few decades, coupled with improvements of fabrication technology that have enabled investigation of previously unrealisable optical scattering systems. Such development is complemented by renewed impetus to understand the physics of optical scattering from complex subwavelength geometry and nanoparticle systems. Here I investigate speci cally the optical properties of closely packed arrangements of nanoparticles, known as nanoparticle oligomers, which provide an intuitive platform for analytical and numerical study on the formation and interplay of collective resonances. I consider both plasmonic nanoparticles, and also high-refractive-index dielectric nanoparticles that support Mie-type electric and magnetic dipole resonances. Specifi c outcomes of this study are listed as follows. (i) A new model is presented for optical Fano resonances, which is based on interference between nonorthogonal eigenmodes of the associated scattering object. This is demonstrated to correctly describe Fano resonances in both plasmonic and high-refractive-index dielectric nanoparticle oligomers; it also revealed capacity for two-channel Fano interference in the magnetic dipolar response from the dielectric oligomers. (ii) Polarisation-independent scattering and absorption losses are shown to be enforced by n-fold discrete rotational symmetry, Cn (n \geq 3), and reciprocal degeneracy of eigenmodes. (iii) A new form of circular dichroism is presented, which occurs due to the interaction of nonorthogonal resonances, and impacts the ratio of radiative scattering loss to dissipative absorption loss experienced by reciprocal plane waves. Geometric asymmetry and optical chirality are also reviewed to quantify the minimum symmetries that must be broken to allow other circular dichroism effects in chiral and achiral scattering objects. The sequence of general theoretical conclusions (i)-(iii) serve to build the understanding of optical scattering from nanoparticle systems while removing existing ambiguities.

abstract: All-dielectric self-supporting (ADSS) fiber optic cables are used for data transfer by the utilities. They are installed along high voltage transmission lines. Dry band arcing, a phenomenon which is observed in outdoor insulators, is also observed in ADSS cables. The heat developed during dry band arcing damages the ADSS cables' outer sheath. A method is presented here to rate the cable sheath using the power developed during dry band arcing. Because of the small diameter of ADSS cables, mechanical vibration is induced in ADSS cable. In order to avoid damage, vibration dampers known as spiral vibration dampers (SVD) are used over these ADSS cables. These dampers are installed near the armor rods, where the presence of leakage current and dry band activity is more. The effect of dampers on dry band activity is investigated by conducting experiments on ADSS cable and dampers. Observations made from the experiments suggest that the hydrophobicity of the cable and damper play a key role in stabilizing dry band arcs. Hydrophobic-ity of the samples have been compared. The importance of hydrophobicity of the samples is further illustrated with the help of simulation results. The results indi-cate that the electric field increases at the edges of water strip. The dry band arc-ing phenomenon could thus be correlated to the hydrophobicity of the outer sur-face of cable and damper.
Dissertation/Thesis
M.S. Electrical Engineering 2011

In this thesis, new all-printed capacitors are developed for the applications of energy storage, filter, and resonant circuits by using new dielectric material and an advanced technology. The innovative devices provide satisficing electrical performances with high breakdown voltages and capacitance densities. The main body of this thesis is divided in three parts. The first part is to introduce the fundamental background of printing technologies, electrical capacitors and printable materials. Among all the printing technologies, direct writing family is the most advantageous in the small-scale and fast production of printed electronics due to the properties of masterless processing, digital control, and print-on-demand. Both inkjet printing and ultrasonic fluid dispensing applied in this work are grouped into the direct writing family. A cross-linkable dielectric material poly(methyl methacrylate)84/(4-benzoylphenyl methacrylate)16 [P(MMA84/BPMA16)] exhibits the optimized chemical and mechanical stabilities in comparison with uncross-linked poly(methyl methacrylate) (PMMA). Poly(vinylidene fluoride-co-trifluoro ethylene) [P(VDF-TrFE)] exhibits a high dielectric constant of 16. The great advantages of both polymeric dielectrics make them ideal for printed electronics. The second part is devoted to the preparation of printed thin-film capacitors by providing four different layouts and architectures for multiple electronic applications. The printing setup, process setting and steps are summarized in detail. The following part which is the major content of this thesis is divided into two aspects: in the first aspect, the intriguing new form of continuous solution dispensing technology, ultrasonic fluid dispensing, is demonstrated as an alternative printing technology for the commonly applied ones. In comparison with the widely-used inkjet printing, continuous solution dispensing is the most advantageous in thin-film capacitor processing with metal nanoparticle and polymer dielectric inks. It enables precise pattern transfers with low surface roughness, small feature size (as small as 5 μm), and accurate positioning (5 μm resolution). Most importantly, problems due to discrete droplets and nozzle clogging in inkjet printing are avoided in continuous solution dispensing. All the inks applied for printed capacitors in this work are printed successfully with this innovating technology. Direct printing on demand and rapid switching among different inks are some other attributes of this printing technology that enable high throughput. The second aspect of this part is to characterize and evaluate the fabricated capacitors. The measured values include capacitor dimension, dielectric strength, capacitance density, energy density, charge/discharge behavior and so on. In summary, this work provides not only the use of the advantageous materials P(MMA84/BPMA16) and P(VDF-TrFE) in high-performance capacitors, but also paves the way of developing thin-film capacitors with a new continuous solution dispensing technology which makes the low-cost and high-quality manufacture of printed devices possible.