Orientador: Flavio Caldas da Cruz / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-09T02:45:38Z (GMT). No. of bitstreams: 1 Nogueira_GiovanaTrevisan_D.pdf: 19393516 bytes, checksum: a3b51900ea17f278fbdc63e608d828d4 (MD5) Previous issue date: 2007 / Resumo: No final da década de 90, pentes de freqüências ópticas baseados em lasers de Ti:safira de modos travados tornaram-se uma importante ferramenta na área de metrologia. Eles têm sido usados, por exemplo, em medidas diretas de freqüências de várias centenas de THz e em relógios atômicos ópticos. Para a implementação de dois sistemas de pentes de freqüências ópticas, desenvolvemos neste trabalho dois lasers de Ti:safira de femtossegundos de alta taxa de repetição, que usam espelhos de varredura (chirped mirros) no lugar de prismas para compensar a dispersão em velocidade de grupo. Um dos lasers tem taxa de repetição em 770 MHz que pode ser facilmente ajustada entre 750 MHz and 1 GHz. A dispersão total da cavidade é de -60 fs2 , produzindo um espectro centrado em 780 nm com largura a meia altura em torno de 10 nm e pulsos de 150 fs. Este laser teve seu espectro alargado por duas fibra de microestrutura, cobrindo um intervalo de 510 à 1100 nm. O outro laser possui cavidade com taxa de repetição sintonizável entre 1 e 2,12 GHz, e um espectro que se estender de de 585 até 1200 nm a -20 dB abaixo do máximo em 986 nm sem o uso de fibra de microestrutura.A cavidade do laser tem dispersão total próxima de zero, porém com oscilações entre -50 a +100 fs2 entre 700 nm e 900 nm, que foi medida por interferometria de luz branca. Nós mostramos que cerca de 17 % (76 %) da potência intracavidade (de saída) é gerada basicamente por efeitos não lineares em passagem única no cristal de Ti:safira, observada na região verde do espectro e entre 960 nm e 1200 nm, fora da banda da cavidade laser e onde o ganho do cristal de Ti:safira é baixo. Ambos os lasers tiveram suas taxas de repetição medidas e estabilizadas em relação a osciladores estáveis, podendo ser sintonizados em um intervalo de 30 kHz através do oscilador de referência. Construímos interferômetros de Michelson e Mach-Zender para a medida do deslocamento entre onda portadora e envelope do pulso do sistema do laser cujo espectro é ampliado pela fibra. O batimento entre freqüências do pente próximas a 520 nm e o segundo harmônico da parte do espectro em 1040 nm é medido em um fotodetector rápido. Estes sistemas serão inicialmente utilizado em um relógio atômico óptico baseado na transição de intercombinação de átomos de cálcio frios e aprisionados. Entretando, além de aplicações em metrologia de tempo e freqüência, os pentes de freqüências ópticas podem ser ferramentas atrativas para uso em espectroscopia atômica e molecular de precisão e estudos de dinâmicas rápidas que exploram a combinação de alta resolução e cobertura espectral larga fornecidas pelo pente de freqüências / Abstract: Optical frequency combs based on femtosecond Ti:sapphire lasers and introduced at the end of the 90s have revolutionized the optical metrology field. They have allowed ultraprecise optical spectroscopy, by direct measurement of frequencies of several hundred THz, and the development of optical atomic clocks . To implement optical frequency combs, we have to stabilize both the repetition rate and the carrier-to-envelope oÿset frequency of the femtosecond laser. We have developed two versions of optical frequency combs based on high-repetition rate femtosecond Ti:sapphire lasers, which use chirped mirrors instead of prisms for compensating the group velocity dispersion. The combs will be initially used in an optical atomic clock based on the intercombination transition of cold and trapped calcium atoms. One of our fsec Ti:sapphire lasers has a repetition rate that can be easily adjusted between 750 MHz and 1 GHz. The total dispersion of the cavity is -60 fs2 . It produces pulses of 150 fs with a spectrum centered at 780 nm, with a width of 10 nm. The spectrum of this laser has been broadened with a microstructure fiber, and covers an optical octave extending from 520 and 1040 nm. The other fsec Ti:sapphire laser has a repetition rate that can be changed from 1 to 2.12 GHz, and a spectrum that extends from 585 nm to 1200 nm, without use of microstructure fibers. These wavelengths are points in the spectrum at -20 dB below the maximum at 986 nm. The laser cavity has total intracavity dispersion near zero, but with oscillations from -50 to +100 fs2 between 700 to 900 nm, that have been measured by white light interferometry. We showed that 17 % (76 %) of the intracavity (output) power is generated by nonlinear effects in a single pass through the crystal, and with a spectral distribution concentrated between 960 nm and 1200 nm, thus outside the laser cavity bandwidth and where the Ti:sapphire gain is lower. Emission in the green has also been observed, which is also outside the laser cavity bandwidth and the emission gain profile of the Ti:sapphire crystal. The repetition rate of both lasers have been phase-locked to stable microwave oscillators, and could also be frequency tuned in a range of 30 kHz with respect to the reference oscillator. We have built f-2f interferometers to measure the carrier-to-envelope oÿset frequency of the laser whose spectrum is broadened by the microstructure fiber. Comb frequencies near 540 nm are heterodyned in a fast photodetector with the second harmonic of the comb light at 1080 nm. In addition to applications in optical time and frequency metrology, the optical frequency combs should be attractive tools for use in precision atomic and molecular spectroscopy, coherent control which exploits the coherent accumulation effect, and studies of fast time dynamics that take advantage of the combination of the ultra high resolution and broadband spectral coverage provided by the comb / Doutorado / Ótica / Doutor em Ciências

Abstract The metamorphosed Palaeoproterozoic Orivesi gold deposit in southern Finland is located within the Tampere Schist Belt, which belongs to the Svecofennian domain. The Orivesi mine, run by Outokumpu Mining Oy, was in production from 1994 to 2003, during which time a total of approximately 1.7 million tons of ore was extracted, with an Au content of 9.31 g/t, implying a total output 13.115 tons of gold in concentrate. The hydrothermal alteration halo can be divided successively into chlorite-dominant, sericite-dominant and quartz-dominant rocks from the outer zone inwards. The host rocks of the ore are quartz rocks with andalusite-rich quartz rocks. Topaz-bearing rocks also occur in the inner part of the alteration halo. In addition to Au, the elements Ag, Te, Bi, Sb, S, As, Se, Cu, Zn, Pb, Sn and Mo are enriched to varying degrees within the alteration halo. The main ore minerals include base metal sulphides, sulphosalts and tellurides. Pyrite is the most common sulphide. The sulphosalts are represented by tetrahedrite, bournonite, boulangerite and meneghinite. The most common gold, gold-silver and silver tellurides are calaverite, montbrayite, petzite, kostovite, sylvanite and hessite. Other known tellurides include tellurobismuthite, altaite, melonite, frohbergite, tsumoite, tetradymite and rucklidgeite. Gold occurs mostly in fine-grained native grains containing an average of 5% Ag. The native gold is usually of very small grain size, generally < 20 µm. Most of the gold grains in the deposit occur as intergrowths with tellurides. The adjacent hypabyssal intrusion is an obvious source of both hydrothermal fluids and metals. A comb quartz layering has been discovered in the transition zone between the intrusion and the alteration halo. The Orivesi deposit is thought to belong to the high-sulphidation epithermal type. Soon after its formation the deposit encountered deformation and metamorphism that amounted to lower amphibolite facies conditions. The subsequent retrograde metamorphism caused the reappearance of some hydrothermal minerals typical of high-sulphidation epithermal deposits.

Silicon photonics has become one of the leading candidates for the next generation optical communication platform. In addition to being an inexpensive material and compatible with Complementary metal–oxide–semiconductor (CMOS) manufacturing, silicon exhibits low absorption at optical telecommunication bands. However, high propagation loss and poor light confinement in narrow Si waveguides have limited high-density optical integration.<br>In this work, we show the fabrication and characterization of a novel type of devices named E-skid devices that can reduce the skin depth and suppress the large spatial content of evanescent light. These devices use artificial anisotropic dielectric metamaterial to suppress the evanescent waves. Beside E-skid devices, we also discuss the fabrication and experimental characterization of mode filters using Silicon on Insulator that can block the fundamental TE0 and allow the higher order modes to pass through using Multi Mode Interference.<br>In this work, the mode is filtered using radiation, not by reflection.<br>Beside Silicon, Silicon Nitride has also gained much interest because of its low loss, smaller nonlinear absorption and higher Kerr effect. Silicon Nitride waveguides have widely<br>been used for lots of applications specially the optical frequency comb generation. One special case of coherent optical frequency comb is Soliton in which case the non-linearity and dispersion cancel each other’s effect and keep the pulse without distortion. In this work, we described the Silicon Nitride fabrication process and did a comparative analysis with other research groups who fabricates similar devices. We tried to improve our process by inserting a few additional steps in our fabrication process. We also investigated our process step by step and found out reasons for our low quality factor and low yield. We found a few factors that might be responsible for the low quality factor and addressed them. We fabricated real devices using our modified process and saw improvement in quality factors, yield and thermal performance of the devices.<br>Finally, we describe an edge polishing method for Silicon Nitride microring resonator devices, which we developed from scratch and we can polish edges down to sub-micron level. Thus, the edges become optically flat and it allowed us to do heterogeneous integration with an Indium Phosphide chip. This paves away for some exciting opportunities like on-chip frequency comb generation.<br><br>

Kvantové kaskádové laserové frekvenční hřebeny jsou slibnými kandidáty pro nové miniaturizované spektrometry bez pohyblivých částí. Mohou být generovány v samočinném režimu pomocí různých nelinearit vyvolaných asymetrickým ziskem a vlnovodovou disperzí. K simulaci samočinných hřebenů byl použit dostupný vysoce optimalizovaný nástroj založený na modelu postupné vlny. Dále byl rozšířen o funkci zamykání optickým vstřikováním, koherentní techniky ovládání frekvenčních hřebenů. Následné simulace potvrdily uzamčení pomocí vstřikovaného signálu. Bylo zjištěno, že disperze grupové rychlosti (GVD) má významný dopad na rozsah zamykání. GVD byla vypočtena pro typické zařízení a frekvenční hřeben byl uzamčen pomocí optického vstřikování v rozsahu ladění od -2 do 47 MHz.

This master thesis deals with a design of Vivaldi antenna due to its broadband properties suitable for radar applications. The folding of single Vivaldi antenna element into 2D antenna array we achieved required radiation properties. Appropriate design of feeding structure realized by SIW technology we obtained suppression of side lobes and deflection of the main lobe. The work also includes design of 3D Vivaldi antenna array. Modeling, simulation and optimization of antenna array were performed in CST Microwave Studio.

The aim of this master's thesis are the engineering design of solutions for vertical elevator drive storage systém LLH – Schwerlast. The project is composed of technical report ans drawing documentation. The Technical report deals with storage and handling bar material, methods of control and manipulation of storage systems and structural design. In the structural part are designed draft drive and its main parts. The main parts of drive are checked using structural analysis. The drawing documentation is composed of assembly drawing, manufacturing dravings and welded frame drawing.

Les interconnections optiques dans les fermes de données (data centers) nécessitent la mise au point de nouvelles approches technologiques pour répondre aux besoins grandissants en composants d’interface respectant des cahiers de charge drastiques en termes de débit, coût, encombrement et dissipation d’énergie. Les peignes de fréquences optiques sont particulièrement adaptés comme nouvelles sources optiques, à mêmes de générer un grand nombre de porteuses optiques cohérentes. Leur utilisation dans des systèmes de transmission en multiplexage de longueurs d’onde (WDM) et exploitant de nouveaux formats de modulation, peut aboutir à des capacités jamais atteintes auparavant. Ce travail de thèse s’inscrit dans le cadre du projet européen BIG PIPES (Broadband Integrated and Green Photonic Interconnects for High-Performance Computing and Enterprise Systems) et a pour but l’étude de peignes de fréquences générés à l’aide de lasers à verrouillage de modes, à section unique, à base de bâtonnets quantiques InAs/InP et puits quantiques InGaAsP/InP. Nous avons entrepris l’étude de nouvelles couches actives et conceptions de cavités lasers en vue de répondre au cahier des charges du projet européen. Une étude systématique du bruit d’amplitude et de phase de ces sources a en particulier été menée à l’aide de nouvelles techniques de mesure afin d’évaluer leur compatibilité dans des systèmes de transmission à très haut débit. Ces peignes de fréquences optiques ont été utilisées avec succès dans des expériences de transmission sur fibre optique avec des débits records dépassant le Tbit/s par puce et une dissipation raisonnable d’énergie par bit, montrant leur fort potentiel pour les applications d’interconnections optiques dans les fermes de données / The increasing demand for high capacity, low cost, high compact and energy efficient optical transceivers for data center interconnects requires new technological solutions. In terms of transmitters, optical frequency combs generating a large number of phase coherent optical carriers are attractive solutions for next generation datacenter interconnects, and along with wavelength division multiplexing and advanced modulation formats can demonstrate unprecedented transmission capacities. In the framework of European project BIG PIPES (Broadband Integrated and Green Photonic Interconnects for High-Performance Computing and Enterprise Systems), this thesis investigates the generation of optical frequency combs using single-section mode-locked lasers based on InAs/InP Quantum-Dash and InGaAsP/InP Quantum-Well semiconductor nanostructures. These novel light sources, based on new active layer structures and cavity designs are extensively analyzed to meet the requirements of the project. Comprehensive investigation of amplitude and phase noise of these optical frequency comb sources is performed with advanced measurement techniques, to evaluate the feasibility of their use in high data rate transmission systems. Record Multi-Terabit per second per chip capacities and reasonably low energy per bit consumption are readily demonstrated, making them well suited for next generation datacenter interconnects

This essay deals with combs typological developments in shape and apperance during the Migration period and Vendel period, 400 - 700 A.D. as well as their meaning and function in society. The importance of combs mentioned in folklore and mythologies, with focus on both life and death. The combs and their significance are put into an everyday context, from begin a functional object to be a social status carrying symbol in society.

No description available.

In dieser Dissertation werden die mittelalterlichen Kämme aus Knochen und Geweih des nordostdeutschen Raumes in Bezug auf Rohstoffe, Herstellung und Gestaltung analysiert. Um Verbindungen zu angrenzenden gut erschlossenen Fundgebieten erarbeiten zu können, wurde die Materiallücke der Kammfunde in Mecklenburg Vorpommern, Brandenburg und Berlin geschlossen. Mit der hier vorgelegten systematischen Erfassung zu Formen, Verzierung, Kammtypen und Maßangaben sowie der individuellen Darstellung im Katalog sind neu gefundene Artefakte und schon anderweitig publizierte Funde direkt miteinander vergleichbar. Im Kontext mit der umfangreichen Fundaufnahme und Kartierung werden Forschungsfragen zu Handwerk und Handel zur Zeit des Mittelalters gestellt und beantwortet. Experimente zur Rohmaterialbearbeitung und Herstellungsprozessen belegen den Werkzeuggebrauch und den Aufwand, der schon im Mittelalter betrieben werden musste, um einen Kamm herzustellen. Die Erfahrungen von praktisch forschenden HandwerkerInnen des 21. Jahrhunderts flossen in diese Arbeit mit ein. In der Gesamtschau ergibt sich eine Fundverteilung von vier Kammtypen vor allem im nördlichen Bereich des Arbeitsgebietes, mit Werkstätten an nahe dem Wasser gelegenen Handelsplätzen. Chronologische Tendenzen sind erkennbar. So sind beispielsweise einreihige Dreilagenkämme eher im frühen Mittelalter in den nördlichen Siedlungen der Slawen und Wikinger zu verankern, während Langzinkenkämme breiter gestreut in den deutschen Siedlungen ab dem späten Mittelalter zu finden sind. / This dissertation analyses the medieval combs made of bone and antlers of the northeast German region in terms of raw materials, production and design. In order to be able to establish connections to neighbouring well-published sites, and to close the gap in the incomplete research in Mecklenburg-Vorpommern, Brandenburg and Berlin, the comb finds are collectively reviewed here. With the systematic survey of shapes, decorations, comb types and measurements presented here, as well as the individual presentation in the catalogue, newly found artefacts and finds that have already been published elsewhere can be directly compared with each other. In the context of the extensive survey and mapping, research questions on crafts and trade at the time of the Middle Ages are asked and answered. Experiments on raw material processing and manufacturing processes prove the use of tools and the effort undertaken to make a comb even in the Middle Ages. The experiences of practical craftsmen of the 21st century was incorporated into this work. Overall, there is a distribution of four types of combs, especially in the northern part of the study area, with workshops at trading sites near water. Chronological tendencies are recognisable with, for example, single-row three-layer combs being more likely to be present in the northern settlements of the Slavs and Vikings in the early Middle Ages, while long-tooth combs are more widely distributed in German settlements from the late Middle Ages onwards.