Edge Couplers with relaxed Alignment Tolerance for Pick-and-Place Hybrid Integration of III-V Lasers with SOI Waveguides

We report on two edge-coupling and power splitting devices for hybrid integration of III-V lasers with sub-micrometric silicon-on-insulator (SOI) waveguides. The proposed devices relax the horizontal alignment tolerances required to achieve high coupling efficiencies and are suitable for passively aligned assembly with pick-and-place tools. Light is coupled to two on-chip single mode SOI waveguides with almost identical power coupling efficiency, but with a varying relative phase accommodating the lateral misalignment between the laser diode and the coupling devices, and is suitable for the implementation of parallel optics transmitters. Experimental characterization with both a lensed fiber and a Fabry-P\'erot semiconductor laser diode has been performed. Excess insertion losses (in addition to the 3 dB splitting) taken as the worst case over both waveguides of respectively 2 dB and 3.1 dB, as well as excellent 1 dB horizontal loss misalignment ranges of respectively 2.8 um and 3.8 um (worst case over both in-plane axes) have been measured for the two devices. Back-reflections to the laser are below -20 dB for both devices within the 1 dB misalignment range. Devices were fabricated with 193 nm DUV optical lithography and are compatible with mass-manufacturing with mainstream CMOS technology

Eine Untersuchung kommerzieller Terminverwaltungs-Software im Hinblick auf die Kopplung mit natürlichsprachlichen Systemen

Das Projekt COSMA (Cooperative Schedule Management Agent) verfolgt das Ziel, einen maschinellen Sekretariatsassistenten zu erstellen, der Termine mit mehreren Teilnehmern über elektronische Post in natürlicher Sprache weitgehend selbständig vereinbart. COSMA stellt natürlichsprachlichen Service für autonome maschinelle Terminplanungs-Agenten zur Verfügung. Eine Anbindung an unterschiedliche kommerzielle Softwareprodukte zur Terminverwaltung könnte die Generalisierbarkeit der in COSMA verfolgten Ansätze nachhaltig plausibel machen. In der hier dokumentierten Untersuchung wurden im Zeitraum März bis Mai 1995 auf dem deutschen Markt befindlichen Produkte untersucht und bewertet. Einige ermöglichen den Zugang zu ihren Termindaten über eine allgemeine Programmierschnittstelle; doch keines stellt Agentenfähigkeit zur Verfügung: Alle Planungs-und Entscheidungsvorgänge bleiben dem Benutzer überlassen. Eine Einbindung in COSMA ist in vielen Fällen technisch möglich, aber erst nach Entwicklung und Einbindung geeigneter Agentensysteme sinnvoll.The project COSMA (Cooperative Schedule Management Agent) is developing a machine secretarial assistent, that can autonomously schedule appointments with several participants via electronic mail in natural language. COSMA provides natural language service for autonomous appointment scheduling machine agents. Adaptation of different commercial software products for appointment management could support the claim of generality of the approaches pursued within COSMA. The study described in this document includes products available on the German market between March and May 1995. Some allow access to their appointment data via an application program interface, but no one provides any agent functionality; i.e. all planning and decision making is left to the user. For some systems, adaptation to COSMA is possible technically, but seems meaningful only after developing and adapting suitable agent systems

High frequency electro-optic measurement of strained silicon racetrack resonators

The observation of the electro-optic effect in strained silicon waveguides has been considered as a direct manifestation of an induced $\chi^{(2)}$ non-linearity in the material. In this work, we perform high frequency measurements on strained silicon racetrack resonators. Strain is controlled by a mechanical deformation of the waveguide. It is shown that any optical modulation vanishes independently of the applied strain when the applied voltage varies much faster than the carrier effective lifetime, and that the DC modulation is also largely independent of the applied strain. This demonstrates that plasma carrier dispersion is responsible for the observed electro-optic effect. After normalizing out free carrier effects, our results set an upper limit of $8\,pm/V$ to the induced high-speed $\chi^{(2)}_{eff,zzz}$ tensor element at an applied stress of $-0.5\,GPa$. This upper limit is about one order of magnitude lower than the previously reported values for static electro-optic measurements

Funktionelle Analyse von Vacciniavirus-Proteinen

Das Modifizierte Vacciniavirus Ankara (MVA) entstand nach mehr als 500 Passagen des Chorioallantois Vacciniavirus Ankara (CVA) auf Hühnerembryofibroblasten. Mit der Passagierung ging u.a. der Verlust zahlreicher Vacciniavirus Virulenzfaktoren einher, wodurch MVA einen hochattenuierten Phänotyp aufweist. Bei mangelnder Pathogenität für humane Organismen verfügt das MVA jedoch über eine vollständig erhaltene Genexpression inklusive integrierter Fremdgene. Hierdurch bedingt ist MVA ein vielversprechender Kandidat nicht nur als Pockenimpfstoff der dritten Generation, sondern auch als Vektorvakzine gegen zahlreiche Infektionskrankheiten sowie in der Tumor-assoziierten Immunotherapie. Ein wesentliches Charakteristikum der Attenuierung von MVA ist seine fehlende Replikationsfähigkeit in humanen Zellen. Bislang ist es jedoch noch nicht möglich gewesen, die hierfür verantwortlichen genetischen Veränderungen eindeutig zuzuordnen. Vorangegangene Arbeiten wiesen darauf hin, dass sich der beschriebene Effekt zumindest teilweise auf die Zeitspanne zwischen zwei Vorläufern des MVA eingrenzen lässt. So zeigten sich humane HeLa Zellen für das CVA 152 permissiv, während gegenüber dem CVA 386 nur noch eine Semipermissivität bestand. Mit Hilfe einer vergleichenden Sequenzanalyse von CVA 152 und CVA 386 konnten verschiedene Deletionen identifiziert werden, deren Auftreten potentiell verantwortlich für den veränderten Phänotyp von CVA 386 ist. In diesem Zusammenhang wurden im Rahmen dieser Arbeit die Gene C12L, C14L, C15L und C16L der Deletion I und die Gene M1L, M2L und der OLR 037 der Deletion II charakterisiert. Durch Transfektion von Expressionsplasmiden wurden die entsprechenden Proteine bezüglich ihrer Expression und posttranslationalen Modifikation, sowie ihrer subzellulären Verteilung untersucht. So ließ sich für das Protein M2 eine posttranslationale N-Glykosylierung und die Lokalisation innerhalb des trans-medialen Golgiapparats nachweisen. Zusätzlich konnte eine Sekretion des M2 Proteins im Zellüberstand transfizierter 293T-Zellen gezeigt, sowie die bereits publizierte Inhibition der NF-:B-Aktivierung durch extrazellulär zugegebenes M2 Protein eingeleitet werden. Die Proteine C14 und C15 zeigten sich in der Laserscanmikroskopie mitochondrial lokalisiert; C16 dagegen kolokalisierte neben einer hauptsächlich intranukleären Verteilung zusätzlich mit F-Aktin. Ferner ergaben sich für die Proteine C14 und C15 erste Hinweise auf eine inhibitorische Funktion gegenüber Staurosporin-induzierter Apoptose.Modified Vaccinia Virus Ankara (MVA) emerged after more than 500 passages of chorioallantois vaccinia virus Ankara (CVA) on chicken embryo fibroblasts. The passaging was accompanied by the loss of numerous vaccinia virus encoded virulence factors, whereby MVA obtained a highly attenuated phenotype. Lacking pathogenicity for human beings, MVA nevertheless is able to express its complete genome, including inserted foreign genes. Hence, MVA is a promising candidate not only as a third generation pox-vaccine but also as a vector vaccine against numerous infectious diseases as well as for tumor associated immunotherapy. An essential feature of the attenuation of MVA is its replication deficiency on human cell lines. So far, it has not been possible to identify the genetic alteration responsible for this phenotype. Previous work suggests that this effect can be allocated at least partially to the time period between two progenitors of MVA. Indicatively, human HeLa cells appeared to be permissive for CVA 152 but only semipermissive for CVA 386 infection. By means of a sequential analysis of CVA 152 and CVA 386 different deletions could be identified whose occurrence is potentially responsible for the altered phenotype of CVA 386. Therefore, the genes C12L, C14L, C15L and C16L of deletion I and M1L, M2L and open reading frame (ORF) 037 of deletion II have been characterized in this work. The appropriate proteins have been studied with the help of expression plasmids by transfection of cells analysing posttranslational modification as well as subcellular localization. Regarding the protein M2 a posttranslational N-glycosylation and a localization within the trans-medial Golgi apparatus could be demonstrated. Additionally, a secretion of M2 into cellular supernatants of transfected 293T cells could be shown. Further, the previously described NF-:B-activation inhibitory effect of M2 could be characterized to be initiated from extracellularly added M2 protein. In laserscan microscopy, mitochondrial localization of the proteins C14 and C15 was detected. C16, on the other hand, besides a primarily intranuclear dispersal was additionally found to colocalize with F-actin. Moreover, additional experiments provided first evidence of an inhibitory function of the C14 and C15 proteins towards Staurosporin-induced apoptosis of BHK cells

Requirements for Terpene Cyclizations inside the Supramolecular Resorcinarene Capsule: Bound Water and its Protonation Determine the Catalytic Activit

he elucidation of the requirements for efficient catalysis within supramolecular host systems is an important prerequisite for developing novel supramolecular catalysts. The resorcinarene hexamer has recently been shown to be the first supramolecular catalyst to promote the tail-to-head terpene cyclization in a biomimetic fashion. We herein present the synthesis of a number of resorcinarene-based macrocycles composed of different ratios of resorcinol and pyrogallol units capable of self-assembly and compare the corresponding assemblies regarding their catalytic activity in the cyclization of monoterpenes. The assemblies were investigated in detail with respect to a number of properties including the encapsulation of substrate and ion pairs, the structural incorporation of water, and the response to externally added acid (HCl). The results obtained strongly indicate that water incorporated into the hydrogen-bond network of the self-assembled structure plays an integral role for catalysis, effectively acting as a proton shuttle to activate the encapsulated substrate. These findings are also supported by molecular dynamics simulations, providing further insight into the protonation pathway and the relative energies of the intermediates involved

Eine Untersuchung kommerzieller Terminverwaltungs-Software im Hinblick auf die Kopplung mit natürlichsprachlichen Systemen

Das Projekt COSMA (Cooperative Schedule Management Agent) verfolgt das Ziel, einen maschinellen Sekretariatsassistenten zu erstellen, der Termine mit mehreren Teilnehmern über elektronische Post in natürlicher Sprache weitgehend selbständig vereinbart. COSMA stellt natürlichsprachlichen Service für autonome maschinelle Terminplanungs-Agenten zur Verfügung. Eine Anbindung an unterschiedliche kommerzielle Softwareprodukte zur Terminverwaltung könnte die Generalisierbarkeit der in COSMA verfolgten Ansätze nachhaltig plausibel machen. In der hier dokumentierten Untersuchung wurden im Zeitraum März bis Mai 1995 auf dem deutschen Markt befindlichen Produkte untersucht und bewertet. Einige ermöglichen den Zugang zu ihren Termindaten über eine allgemeine Programmierschnittstelle; doch keines stellt Agentenfähigkeit zur Verfügung: Alle Planungs-und Entscheidungsvorgänge bleiben dem Benutzer überlassen. Eine Einbindung in COSMA ist in vielen Fällen technisch möglich, aber erst nach Entwicklung und Einbindung geeigneter Agentensysteme sinnvoll.The project COSMA (Cooperative Schedule Management Agent) is developing a machine secretarial assistent, that can autonomously schedule appointments with several participants via electronic mail in natural language. COSMA provides natural language service for autonomous appointment scheduling machine agents. Adaptation of different commercial software products for appointment management could support the claim of generality of the approaches pursued within COSMA. The study described in this document includes products available on the German market between March and May 1995. Some allow access to their appointment data via an application program interface, but no one provides any agent functionality; i.e. all planning and decision making is left to the user. For some systems, adaptation to COSMA is possible technically, but seems meaningful only after developing and adapting suitable agent systems

Fabrication tolerant high-speed SiP ring modulators and optical add-drop multiplexers for WDM applications

Silicon ring resonator modulators (RRMs) have great potential to reduce footprint and power consumption and to increase modulation speeds in wavelength division multiplexed (WDM) transmitters. However, the optical properties of RRMs are highly sensitive to fabrication variations, which makes them challenging to design for volume production or a large number of WDM-channels. In this work, we present an RRM design that was specifically designed and experimentally validated to have reduced sensitivity to fabrication variations. This includes a sensitivity analysis of resist over- and under-exposure (±30 nm lateral dimension deviation) and of etch depth variability (±10 nm depth variation) within the coupling section. For our design, the deviation from the targeted coupling strength is improved twofold. The proposed devices are fabricated on SOI wafers using a standard CMOS-compatible process. We demonstrate RRMs with an extinction ratio above 5 dB, an OMA better that -7 dB (at 2 Vpp) and a 29 GHz electro-optical bandwidth, showing open eye diagrams at 32 Gb/s limited only by our measurement setup. The measured coupling coefficients are in good agreement with the simulated values. Furthermore, we applied the same design modifications to realize low-doped RRMs as well as ring based adddrop-multiplexers (OADMs). The agreement between the simulated and the measured coupling coefficients (that we identified as the main source of device performance variability) further confirms the effectiveness of our design modifications. These results suggest that the proposed design can be exploited to enable reliable fabrication of resonantbased devices on a large scale, especially in WDM systems