TY - JOUR AU - Padberg, Laura AU - Santandrea, Matteo AU - Rüsing, Michael AU - Brockmeier, Julian AU - Mackwitz, Peter AU - Berth, Gerhard AU - Zrenner, Artur AU - Eigner, Christof AU - Silberhorn, Christine ID - 25920 JF - Optics Express SN - 1094-4087 TI - Characterisation of width-dependent diffusion dynamics in rubidium-exchanged KTP waveguides ER - TY - JOUR AB - Optically nonlinear Pb2B5O9X (X = Cl, Br) borate halides are an important group of materials for second harmonic generation (SHG). Additionally, they also possess excellent photocatalytic activity and stability in the process of dechlorination of chlorophenols, which are typical persistent organic pollutants. It would be of great interest to conduct in situ (photo‐) catalysis investigations during the whole photocatalytic process by SHG when considering them as photocatalytic materials. In order to get superior photocatalytic efficiency and maximum surface information, small particles are highly desired. Here, a low‐cost and fast synthesis route that allows growing microcrystalline optically nonlinear Pb2B5O9X borate halides at large quantities is introduced. When applying the ionothermal growth process at temperatures between 130 and 170 °C, microcrystallites with an average size of about 1 µm precipitate with an orthorhombic hilgardite‐like borate halide structure. Thorough examinations using powder X‐ray diffraction and scanning electron microscopy, the Pb2B5O9X microcrystals are indicated to be chemically pure and single‐phased. Besides, the Pb2B5O9X borate halides' SHG efficiencies are confirmed using confocal SHG microscopy. The low‐temperature synthesis route thus makes these borate halides a highly desirable material for surface studies such as monitoring chemical reactions with picosecond time resolution and in situ (photo‐) catalysis investigations. AU - Tan, Deming AU - Kirbus, Benjamin AU - Rüsing, Michael AU - Pietsch, Tobias AU - Ruck, Michael AU - Eng, Lukas M. ID - 47956 IS - 23 JF - Small KW - Biomaterials KW - Biotechnology KW - General Materials Science KW - General Chemistry SN - 1613-6810 TI - Resource‐Efficient Low‐Temperature Synthesis of Microcrystalline Pb2B5O9X (X = Cl, Br) for Surfaces Studies by Optical Second Harmonic Generation VL - 16 ER - TY - JOUR AB - High-fidelity periodic poling over long lengths is required for robust, quasi-phase-matched second-harmonic generation using the fundamental, quasi-TE polarized waveguide modes in a thin-film lithium niobate (TFLN) waveguide. Here, a shallow-etched ridge waveguide is fabricated in x-cut magnesium oxide doped TFLN and is poled accurately over 5 mm. The high fidelity of the poling is demonstrated over long lengths using a non-destructive technique of confocal scanning second-harmonic microscopy. We report a second-harmonic conversion efficiency of up to 939 %/W (length-normalized conversion efficiency 3757 %/Wcm²), measured at telecommunications wavelengths. The device demonstrates a narrow spectral linewidth (1 nm) and can be tuned precisely with a tuning characteristic of 0.1 nm/°C, over at least 40 °C without measurable loss of efficiency. AU - Zhao, Jie AU - Rüsing, Michael AU - Javid, Usman A. AU - Ling, Jingwei AU - Li, Mingxiao AU - Lin, Qiang AU - Mookherjea, Shayan ID - 47958 IS - 13 JF - Optics Express KW - Atomic and Molecular Physics KW - and Optics SN - 1094-4087 TI - Shallow-etched thin-film lithium niobate waveguides for highly-efficient second-harmonic generation VL - 28 ER - TY - JOUR AB - Quasi-phase-matched grating structures in lithium niobate waveguides with sub-micrometer periodicities will benefit the development of short-wavelength nonlinear optical devices. Here, we report on the reproducible formation of periodically poled domains in x-cut single-crystalline thin-film lithium niobate with periodicities as short as 600 nm. Shaped single-voltage poling pulses were applied to electrode structures that were fabricated by a combination of electron-beam and direct-writing laser lithography. Evidence of successful poling with good quality was obtained through second-harmonic microscopy and piezoresponse force microscopy imaging. For the sub-micrometer period structures, we observed patterns with a double periodicity formed by domain interactions and features with sizes <200 nm. AU - Zhao, Jie AU - Rüsing, Michael AU - Roeper, Matthias AU - Eng, Lukas M. AU - Mookherjea, Shayan ID - 47955 IS - 19 JF - Journal of Applied Physics KW - General Physics and Astronomy SN - 0021-8979 TI - Poling thin-film x-cut lithium niobate for quasi-phase matching with sub-micrometer periodicity VL - 127 ER - TY - JOUR AU - Zhao, Jie AU - Ma, Chaoxuan AU - Rüsing, Michael AU - Mookherjea, Shayan ID - 47952 IS - 16 JF - Physical Review Letters KW - General Physics and Astronomy SN - 0031-9007 TI - High Quality Entangled Photon Pair Generation in Periodically Poled Thin-Film Lithium Niobate Waveguides VL - 124 ER - TY - CONF AU - Rüsing, Michael AU - Roeper, M. AU - Amber, Z. AU - Kirbus, B. AU - Eng, L.M. AU - Zhao, J. AU - Mookherjea, S. ID - 47959 T2 - 2020 Joint Conference of the IEEE International Frequency Control Symposium and International Symposium on Applications of Ferroelectrics (IFCS-ISAF) TI - Periodic Poling of X-Cut Thin-Film Lithium Niobate: The Route to Submicrometer Periods ER - TY - JOUR AB - The aim of this study was to find out whether teaching how to search for literature would be more beneficial to students and teachers if done online through short videos rather than in person during course time. To find out whether online videos are more beneficial, two courses were asked to fill in questionnaires, one at the beginning and one at the end of the semester. One of the courses received the input online via videos and were given an exercise to put the newly learned skills to use, the other course served as a control group and learned how to search for literature during the course. The results show that while the difference between the two groups is not significant, the videos can still be regarded as being more beneficial than teaching the necessary skills during course time. AU - Hahn, Charlotte Anna ID - 33299 IS - 6 JF - die hochschullehre KW - E-Learning KW - information competence KW - literature KW - library KW - research TI - Informationskompetenz durch E-Learning? Durch Lernvideos nach Literatur suchen ER - TY - JOUR AU - Gretz, Daniela ID - 48054 IS - 1 JF - Jahrbuch der Raabe-Gesellschaft KW - General Medicine SN - 1865-8857 TI - Zwischen romantischem Fragment und Skizze/n der Moderne. Zum medialen Realismus von Wilhelm Raabes "Wer kann es wenden?" VL - 61 ER - TY - CONF AB - The detection of orchestrated and potentially manipulative campaigns in social media is far more meaningful than an- alyzing single account behaviour but also more challenging in terms of pattern recognition, data processing, and com- putational complexity. While supervised learning methods need an enormous amount of reliable ground truth data to find rather inflexible patterns, classical unsupervised learn- ing techniques need a lot of computational power to handle large amount of data. This makes them infeasible for real- time analysis. In this work, we demonstrate the applicability of text stream clustering for the real-time detection of coordi- nated campaigns. AU - Assenmacher, D AU - Adam, L AU - Trautmann, Heike AU - Grimme, C ID - 46319 T2 - Proceedings of the Florida Artificial Intelligence Research Society Conference TI - Towards Real-Time and Unsupervised Campaign Detection in Social Media ER - TY - THES AB - In der Forschungsarbeit wird die Zeitungskommunikation des 18. Jahrhunderts aus sprachwissenschaftlicher Perspektive untersucht. Es wird gezeigt, wie sich das Textsortenrepertoire der Zeitung weiterentwickelte, welche sprachlichen Wandelprozesse stattfanden und wie die Zeitung übergreifend allmählich zu einem Massenmedium avancierte. Der textlinguistische Zugang auf die Zeitungssprache wird an den relevanten Stellen ergänzt durch einschlägige Erkenntnisse aus der historischen Presseforschung und der linguistischen Kulturanalyse. So wird etwa nachgezeichnet, wie sich die Zeitungsschreiber im Laufe des Jahrhunderts immer stärker von den Einflüssen der Kanzleisprachen lösten und Formulierungsstrategien etablierten, die auf die Anforderungen des journalistischen Berichtens abgestimmt waren. Mit diesen und weiteren Ergebnissen wird der Versuch angestellt, eine Forschungslücke der Sprachgeschichtsforschung zu schließen, in der die Zeitungen des 18. Jahrhunderts bisher lediglich randständig untersucht wurden. AU - Wille, Manuel ID - 48272 KW - text linguistics KW - newspaper KW - Hamburgischer Correspondent KW - Textlinguistik KW - Sprachgeschichte KW - Textsortenwandel KW - Korpuslinguistik SN - 978-3-347-16354-6 TI - Die Tageszeitung des 18. Jahrhunderts auf dem Weg zum Massenmedium VL - 15 ER -