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 -