Organic semiconductor lasers with two-dimensional distributed feedback

The work at hand presents a comprehensive investigation of solid-state lasers based on thin films of a disordered organic semiconductors (OS). The high luminescence yield of OS together with their conductivity and the ease of processing them into sub-micron thick films on substrates of virtually any shape and size open vast opportunities both for the realization of novel devices and for the exploration of innovative resonator geometries. Within the course of this work optically pumped lasers with spatially distributed feedback were fabricated by deposition of a thin film of an OS on a nanopatterned substrate. Upon optical excitation with femtosecond laser pulses laser operation is observed. It is characterized using time-integrated and time-resolved spectroscopy. As active medium two of the most promising electroluminescent organic materials were employed, namely the conjugated polymer MeLPPP and the composite molecular system Alq3:DCM. Owing to their large gain coefficient low-threshold light-amplification by stimulated emission can be observed from slab waveguides formed by a thin layer of the OS on a planar substrate. In periodically modulated waveguides Bragg scattering gives rise to distributed feedback. Utilizing UV-embossed plastic substrates with an appropriate onedimensional surface corrugation, edge- and surface-emitting lasers were fabricated. Excellent agreement is found between the performance of these 1D-DFB lasers and the predictions of a quantitative numerical modeling. Unless further precautions are taken these lasers operate on a continuum of lateral modes, characterized by a broad emission spectrum and a large beam divergence. A significantly improved performance is achieved by application of a two-dimensional corrugation. The specific properties of light-propagation in the resulting 2D photonic crystal give rise to monomode laser operation, accompanied by a reduction of the laser threshold, an increased differential efficiency, and by the emission of a circularly shaped, diffractionlimited laser beam. It is demonstrated that the emission linewidth is (time-bandwidth) transform limited by the duration of the laser pulse. The mechanism leading to monomode operation at low excitation density as well as the photonic band structure at high excitation density is revealed by a Laue model for the feedback in such a 2D photonic crystal laser. By use of a self-assembly technique waveguide structures with stochastically distributed scatter centers were fabricated. Lasing with resonant feedback is observed and attributed to the formation of random closed loop cavities (random lasing). The underlying process of recurrent light-scattering is made possible by the strong scattering, the reduced dimensionality of the waveguide geometry, and the large gain of the organic semiconductor material. In order to explore the technological potential of organic semiconductor lasers two alternative concepts for electrical operation were examined. In a hybrid concept an OS DFB laser is merely used as a tunable solid-state laser source. Thanks to the low laser threshold a very compact setup can be realized utilizing a microchip pump laser with a repetition rate of several kilohertz. In the approach of making an organic diode laser the low mobility of disordered organic semiconductors imposes severe constraints on the device architecture. Several structures were developed and fabricated that concurrently permit large current densities and possess a low laser threshold. As a result, optically pumped lasing is for the first time demonstrated in structures that are suitable for electrical excitation.1 Die vorliegende Arbeit beinhaltet eine umfassende Untersuchung dünner organischer Halbleiterfilme hinsichtlich ihrer Einsatzmöglichkeiten in Festkörperlasern. Die einzigartige Kombination ihrer elektrischen Eigenschaften, der hohen Lumineszenzausbeute sowie der einfachen Verarbeitung eröffnet eine Vielzahl neuer Anwendungen in der Optoelektronik und ermöglicht insbesondere die Erprobung innovativer Laserresonatoren. Im Rahmen dieser Doktorarbeit wurden Laser mit räumlich verteilter Rückkopplung hergestellt und untersucht (engl.: distributed feedback, DFB). Sie bestehen aus einem dünnen organischen Halbleiterfilm der auf ein vorstrukturiertes Substrat aufgebracht wird, so dass sich ein räumlich modulierter Dünnschichtwellenleiter ausbildet. Die Lasertätigkeit wird durch Bestrahlung mit Femtosekunden-Laserpulsen angeregt und mittels zeitaufgelöster sowie zeitintegrierender Spektroskopietechniken analysiert. Mit dem konjugierten Polymer MeLPPP und dem molekularen Verbundmaterial Alq3:DCM kamen zwei aussichtsreiche elektrolumineszierende organische Halbleiter zum Einsatz. Ihr hoher Wirkungsquerschnitt für stimulierte Emission bewirkt eine effiziente optische Verstärkung und resultiert in einem äußerst niedrigen Schwellwert für die Beobachtung verstärkter spontaner Emission in planaren Wellenleitern. Die Bragg-Beugung in einem periodisch modulierten Wellenleiter kann ausgenützt werden, um spektral selektive Rückkopplung zu erzielen. Unter Verwendung von geprägten Plastiksubstraten mit eindimensional periodischer Oberflächenmodulation wurden auf diese Weise sowohl kanten- als auch oberflächenemittierende 1D-DFB Laser realisiert. Ihre Lasertätigkeit wurde umfassend charakterisiert und modelliert. Sofern keine weiteren Vorkehrungen zur Modenselektion getroffen werden, ergibt sich ein kontinuierliches Spektrum lateraler Moden, das sich in einem verbreiterten Emissionsspektrum und einer hohen Strahldivergenz niederschlägt. Eine erhebliche Verbesserung der Abstrahlcharakteristik wurde durch den Einsatz 2D periodisch modulierter Substrate erzielt. Die spezifischen Eigenheiten der Lichtausbreitung in einem solchen 2D photonischen Kristall führen zu monomodiger Lasertätigkeit, die sich durch eine reduzierte Laserschwelle, erhöhte Effizienz und beugungsbegrenzte Abstrahlung auszeichnet. Zudem ist die spektrale Linienbreite allein durch die Dauer des emittierten Laserpulses begrenzt. Sowohl die Ursache der monomodigen Lasertätigkeit als auch die photonische Bandstruktur bei hoher Anregung lassen sich durch ein Laue-Modell der Rückkopplung in photonischen Kristall-Lasern erklären. Mit Hilfe einer Selbstorganisationstechnik wurden darüber hinaus Wellenleiterstrukturen mit stochastisch verteilten Streuzentren hergestellt. Lasertätigkeit mit resonanter Rückkopplung wird hierbei durch Vielfachstreuung innerhalb des Wellenleiters und die zufällige Ausbildung geschlossener optischer Pfade erreicht (Random Lasing). Um das technologische Potential organischer Halbleiterlaser auszuloten, wurden zwei Konzepte zur elektrischen Ansteuerung untersucht. In einem hybriden Ansatz dient der organische Halbleiterlaser lediglich als durchstimmbare Festkörperstrahlquelle. Aufgrund der geringen Laserschwelle läßt sich ein äußerst kompakter Aufbau mit einem gepulsten Mikrochip Pumplaser realisieren. Für die alternative Verwirklichung eines elektrisch betriebenen organischen Diodenlasers ist die Entwicklung von Strukturen essentiell, die trotz der geringen Ladungsträgerbeweglichkeit in ungeordneten organischen Halbleitern gleichzeitig geringe Laserschwellen und hohe elektrische Stromdichten ermöglichen. Im Rahmen dieser Arbeit konnte erstmalig Lasertätigkeit in Strukturen nachgewiesen werden, die für diese hohe elektrische Anregung geeignet sind

Sustainable factory profile : A concept to support the design of future sustainable industries

Part of: Seliger, Günther (Ed.): Innovative solutions : proceedings / 11th Global Conference on Sustainable Manufacturing, Berlin, Germany, 23rd - 25th September, 2013. - Berlin: Universitätsverlag der TU Berlin, 2013. - ISBN 978-3-7983-2609-5 (online). - http://nbn-resolving.de/urn:nbn:de:kobv:83-opus4-40276. - pp. 72–77.The German industry caused more than a quarter (27.8%) of the total energy consumption. Factories have a high influence in resource saving during the realization of a factory and the production process. First “CO2 neutral factories” and “zero-emission factories” were realized in the last years. But they are just point solutions and these concepts are rarely used by enterprises in Germany. As part of an energy efficient optimization of factories, it is necessary to extend the focus of planning and to consider the location, the design, the integration into the environment and the potential of modern energy efficiency. Particularly the factories provides additional high saving potentials for the company. Low emission production methods or resourceefficient building practices offer opportunities for integrated environmental factory design. These approaches are integrated into the comprehensive concept “Sustainable Factory Profile (SFP)” which is described in this paper

O Teatro do Sol

Este artigo pretende investigar a presença de aspectos e princípios teatrais defendidos pelo diretor, autor e ator francês Jacques Copeau (1879-1949) no trabalho da diretora, também francesa, Ariane Mnouchkine (1939) à frente do Théâtre du Soleil. Pretende ainda examinar de que forma, no âmbito de processos práticos, tais aspectos e princípios se prolongam na formação de atores da trupe francesa

Quartiersebene als Infrastrukturverbund - Klimaschutzpotenziale und Synergien mit dem Umweltschutz

QUARTIERSEBENE ALS INFRASTRUKTURVERBUND - KLIMASCHUTZPOTENZIALE UND SYNERGIEN MIT DEM UMWELTSCHUTZ Quartiersebene als Infrastrukturverbund - Klimaschutzpotenziale und Synergien mit dem Umweltschutz / Riechel, Robert (Rights reserved) ( -

A formação artístico-cultural dos professores da educação Infantil e suas implicações no cotidiano com as crianças.

Trabalho de Conclusão do Curso de Especialização em Educação Infantil - Segunda Edição – Polo Florianópolis, para a obtenção do Grau de Especialista em Educação Infantil.A presente pesquisa tem por objetivo apresentar as diferentes nuanças do processo de formação artístico-cultural dos professores da Educação Infantil e apontar como tal formação afeta o trabalho cotidiano com as crianças. Neste estudo a trajetória seguida foi de uma reflexão inicial sobre a arte, um pouco da sua história e os diferentes caminhos que ela percorre, destacando, desta maneira, a importância da arte na formação do ser humano. Cabe mencionar que a pesquisa bibliográfica se utilizou de outras vozes (pesquisadores) que com seus estudos trouxeram grandes contribuições para a discussão. O trabalho teceu reflexões sobre o papel do professor de Educação Infantil, bem como algumas possibilidades de trabalho com a arte para a faixa etária de 0 a 3 anos de idade.Trouxe ainda o debate de questões referentes a formação, não só institucional, mas também questões sobre as condições objetivas de trabalho e de acesso aos bens culturais na nossa sociedade. Ao final são referendados alguns registros de situações vivenciadas no cotidiano das instituições de Educação Infantil na qual a autora do trabalho atuou como professora, caracterizando um cenário de pesquisa-ação

A phased approach to distribution network optimization given incremental supply chain change

Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division; in conjunction with the Leaders for Global Operations Program at MIT, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 59-60).This thesis addresses the question of how to optimize a distribution network when the supply chain has undergone an incremental change. A case study is presented for Company A, a major global biotechnology company that recently acquired a new manufacturing facility in Ireland. Company A already has international operations throughout Europe and the rest of the world through its network of 3rd party logistics providers, wholesalers, and distributors, as well as its own Benelux-based international distribution center. It now seeks to optimize its current network by taking into consideration the possibility of distributing product directly out of Ireland and by potentially outsourcing some of the distribution currently sourced from its Benelux facility. The thesis uses a phased approach to optimizing the network in order to tackle the common enterprise challenges of 1) building consensus around the solution and 2) simultaneously learning about the problem while attempting to solve it in order to meet a compressed project schedule. Through a number of simplifications, the thesis reduces the problem scope to a level that both enables the use of this phased approach and provides for a less-complex and less time-intense analysis manageable within the given time frame. The unique characteristics of the biotechnology industry drive the analysis to closely study direct effects of and potential risks to availability and lead-time of the various distribution options while trading off distribution, packaging, inventory, and capital expenditure costs. The recommendations resulting from the analysis described in this thesis are used to inform Company A's future distribution strategy regarding additional warehousing capacities, the continued use of the Benelux facility, as well as potential strategic partnerships with 3rd party logistics service providers.by Patrick Riechel.S.M.M.B.A

AUBURN, CA, EVACUATION PLAN

Auburn is a small but famous gold mining and railroad town in the Sierra Nevada Mountains of Placer County, California. The city has seen recent and historically reoccurring wildfires. In 2021, 1.5 million acres burned in the Sierra Nevada Mountains, a new record. Auburn consists of three (3) nonadjacent and nonoverlapping sections or parcels of land. The three (3) centroids of each section of Auburn are identified and used in three (3) evacuation scenarios: First, Auburn is evacuated away from the three (3) centroids. We look at how far evacuees can reach in 5, 10, 15, and 30 minutes using emergency vehicle travel times, so signal lights, one-way streets, etc., are ignored. Second, we evacuate away from the three (3) centroids while also avoiding previous burn areas. Third, we evacuate Auburn toward the only area hospital, a structure likely to be defended from fire by first responders. Also, some evacuees might require medical attention. Future work includes looking at how far emergency vehicles from places like fire stations can reach in 5, 10, 15, and 30 minutes, providing a coverage area for first responders

Die kommunale Wärmewende

Für die Realisierung der internationalen Klimaschutzverpflichtungen ist eine umfassendeTransformation der städtischen Wärmeversorgungssysteme notwendig. Die kommunale Wärmewende erfordert erhebliche strategische Anstrengungen

Hearing: a pediatrician s approach

Hearing plays a fundamental role in a child s global development; however, some professionals do not realize how much they may contribute to mitigate the sequelae caused by hearing impairment. AIM: to collect data on pediatricians approaches in a city in the country side of Santa Catarina State, regarding the early detection of hearing impairment and identify the methodology utilized for its diagnosis. STUDY DESING: Historical Cohort with Cross-Sectional Cohort. MATERIALS AND METHODS: Analysis of questionnaires with nine multiple choice questions and ten open questions. RESULTS: 62% reported that their training in hearing disorders happened during their medical course; high risk patients are referred to the otorhinolaryngologist (92%); 83% said they are aware of the evaluation techniques; 55% stated they were not aware of the different types of hearing loss; only 25% reported they knew about the levels of hearing loss and 42% of the interviewees believe a child may have fruitful use of a hearing aid before six months of age. CONCLUSION: There is the need of more information about the importance of early diagnosis, as well as the methods used for this end.A audição exerce fundamental importância no desenvolvimento global da criança, porém, alguns profissionais desconhecem a contribuição que podem dar para reduzir ou minimizar as seqüelas deixadas por uma perda auditiva. OBJETIVO: Coletar dados referentes à conduta dos pediatras, de uma cidade do interior de Santa Catarina, frente à detecção precoce da deficiência auditiva e identificar a metodologia utilizada para o diagnóstico. FORMA DE ESTUDO: Coorte histórico com corte transversal. MATERIAL E MÉTODO: Análise de questionários, com dez questões abertas e nove fechadas. RESULTADOS: 62% informaram que sua formação sobre deficiência auditiva ocorreu durante a graduação; conduta nos casos de alto risco (92%) é o encaminhamento ao otorrinolaringologista; 83% referem conhecer as técnicas de avaliação, 55% afirmam desconhecer os tipos de perda auditiva, apenas 25% mencionam conhecer os graus de perda auditiva e 42% dos entrevistados acreditam que uma criança pode fazer uso da prótese auditiva antes dos seis meses. CONCLUSÃO: A necessidade de mais informações sobre a importância do diagnóstico precoce, bem como dos métodos utilizados para realização deste, mostrou-se evidente neste estudo.Universidade Tuiuti do ParanáUniversidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM)Universidade Tuiuti do Paraná Programa de Mestrado em Distúrbios da ComunicaçãoUniversidade Federal do ParanáUniversidade Tuiuti do Paraná Programa de Pós-Graduação em Distúrbios da ComunicaçãoUNIFESP, EPMSciEL