@article{10014, abstract = {{The cubic, tetragonal, and orthorhombic phase of potassium niobate (KNbO3) are studied based on density-functional theory. Starting from the relaxed atomic geometries, we analyze the influence of self-energy corrections on the electronic band structure within the GW approximation. We find that quasiparticle shifts widen the direct (indirect) band gap by 1.21 (1.44), 1.58 (1.55), and 1.67 (1.64) eV for the cubic, tetragonal, and orthorhombic phase, respectively. By solving the Bethe-Salpeter equation, we obtain the linear dielectric function with excitonic and local-field effects, which turn out to be essential for good agreement with experimental data. From our results, we extract an exciton binding energy of 0.6, 0.5, and 0.5 eV for the cubic, tetragonal, and orthorhombic phase, respectively. Furthermore, we investigate the nonlinear second-harmonic generation (SHG) both theoretically and experimentally. The frequency-dependent second-order polarization tensor of orthorhombic KNbO3 is measured for incoming photon energies between 1.2 and 1.6 eV. In addition, calculations within the independent-(quasi)particle approximation are performed for the tetragonal and orthorhombic phase. The novel experimental data are in excellent agreement with the quasiparticle calculations and resolve persistent discrepancies between earlier experimental measurements and ab initio results reported in the literature.}}, author = {{Schmidt, Falko and Riefer, Arthur and Schmidt, Wolf Gero and Schindlmayr, Arno and Imlau, Mirco and Dobener, Florian and Mengel, Nils and Chatterjee, Sangam and Sanna, Simone}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, number = {{5}}, publisher = {{American Physical Society}}, title = {{{Quasiparticle and excitonic effects in the optical response of KNbO3}}}, doi = {{10.1103/PhysRevMaterials.3.054401}}, volume = {{3}}, year = {{2019}}, } @article{37288, abstract = {{An integrated chip with quantum state generation, active polarization manipulation, and precise time control is demonstrated.}}, author = {{Luo, Kai-Hong and Brauner, Sebastian and Eigner, Christof and Sharapova, Polina and Ricken, Raimund and Meier, Torsten and Herrmann, Harald and Silberhorn, Christine}}, issn = {{2375-2548}}, journal = {{Science Advances}}, keywords = {{Multidisciplinary}}, number = {{1}}, publisher = {{American Association for the Advancement of Science (AAAS)}}, title = {{{Nonlinear integrated quantum electro-optic circuits}}}, doi = {{10.1126/sciadv.aat1451}}, volume = {{5}}, year = {{2019}}, } @article{13284, author = {{Hannes, Wolf-Rüdiger and Meier, Torsten}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{12}}, title = {{{Higher-order contributions and nonperturbative effects in the nondegenerate nonlinear optical absorption of semiconductors using a two-band model}}}, doi = {{10.1103/physrevb.99.125301}}, volume = {{99}}, year = {{2019}}, } @article{13365, abstract = {{The KTiOPO4 (KTP) band structure and dielectric function are calculated on various levels of theory starting from density-functional calculations. Within the independent-particle approximation an electronic transport gap of 2.97 eV is obtained that widens to about 5.23 eV when quasiparticle effects are included using the GW approximation. The optical response is shown to be strongly anisotropic due to (i) the slight asymmetry of the TiO6 octahedra in the (001) plane and (ii) their anisotropic distribution along the [001] and [100] directions. In addition, excitonic effects are very important: The solution of the Bethe–Salpeter equation indicates exciton binding energies of the order of 1.5 eV. Calculations that include both quasiparticle and excitonic effects are in good agreement with the measured reflectivity.}}, author = {{Neufeld, Sergej and Bocchini, Adriana and Gerstmann, Uwe and Schindlmayr, Arno and Schmidt, Wolf Gero}}, issn = {{2515-7639}}, journal = {{Journal of Physics: Materials}}, pages = {{045003}}, publisher = {{IOP Publishing}}, title = {{{Potassium titanyl phosphate (KTP) quasiparticle energies and optical response}}}, doi = {{10.1088/2515-7639/ab29ba}}, volume = {{2}}, year = {{2019}}, } @article{22445, abstract = {{Am Beispiel des chinesisch-deutschen Kooperationsstudiengangs Maschinenbau an der Chinesisch-Deutschen Technischen Fakultät in Qingdao (China) werden unter Rückgriff auf unterschiedliche im Rahmen formativer Evaluation erhobener Datensätze Möglichkeiten und Grenzen der Integration von Fach- und Sprachlernen sowie Optimierungsmöglichkeiten der Unterstützung des studienvorbereitenden und -begleitenden (Fach-)Spracherwerbs diskutiert.}}, author = {{Denzer, Vera and Didier, Andrea and Drumm, Sandra and Hambach, Dennis and Kaplinska-Zajontz, Marta and Noeke, Josef and Settinieri, Julia and Xi, Lin and Zhu, Hongyu}}, isbn = {{2511-0853}}, journal = {{Informationen Deutsch als Fremdsprache}}, number = {{1}}, pages = {{178--199}}, publisher = {{De Gruyter Mouton}}, title = {{{Integration von Sprach- und Fachlernen im Kontext chinesisch-deutscher Kooperationsstudiengänge am Beispiel des Maschinenbaustudiums an der Chinesisch-Deutschen Technischen Fakultät (CDTF, Qingdao/Paderborn)}}}, doi = {{10.1515/infodaf-2019-0013}}, volume = {{46}}, year = {{2019}}, } @article{22887, author = {{Vondran, J. and Spitzer, F. and Bayer, M. and Akimov, I. A. and Trautmann, Alexander and Reichelt, Matthias and Meier, Cedrik and Weber, N. and Meier, Torsten and André, R. and Mariette, H.}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{15}}, pages = {{155308}}, title = {{{Spatially asymmetric transients of propagating exciton-polariton modes in a planar CdZnTe/CdMgTe guiding structure}}}, doi = {{10.1103/physrevb.100.155308}}, volume = {{100}}, year = {{2019}}, } @unpublished{22884, abstract = {{Measurement-induced nonclassical effects in a two-mode interferometer are investigated theoretically using numerical simulations and analytical results. We demonstrate that for certain parameters measurements within the interferometer lead to the occurrence of two-mode squeezing. The results strongly depend on the detection probability, the phase inside the interferometer, and the choice of the input states. The appropriate parameters for maximized squeezing are obtained. We analyze the influence of losses and confirm that the predicted effects are within reach of current experimental techniques.}}, author = {{Riabinin, Matvei and Sharapova, Polina and Bartley, Tim and Meier, Torsten}}, booktitle = {{arXiv:1912.09097}}, title = {{{Generating two-mode squeezing with multimode measurement-induced nonlinearity}}}, year = {{2019}}, } @article{13900, author = {{Song, Xiaohong and Zuo, Ruixin and Yang, Shidong and Li, Pengcheng and Meier, Torsten and Yang, Weifeng}}, issn = {{1094-4087}}, journal = {{Optics Express}}, number = {{3}}, pages = {{2225--2234}}, title = {{{Attosecond temporal confinement of interband excitation by intraband motion}}}, doi = {{10.1364/oe.27.002225}}, volume = {{27}}, year = {{2019}}, } @article{13429, author = {{Bocchini, Adriana and Neufeld, Sergej and Gerstmann, Uwe and Schmidt, Wolf Gero}}, issn = {{0953-8984}}, journal = {{Journal of Physics: Condensed Matter}}, pages = {{385401}}, title = {{{Oxygen and potassium vacancies in KTP calculated from first principles}}}, doi = {{10.1088/1361-648x/ab295c}}, volume = {{31}}, year = {{2019}}, } @inproceedings{22441, abstract = {{According to ISO / ASTM 52900, additive manufacturing (AM) is defined as "the process of joining materials to make parts from 3D model data, usually layer upon layer, as opposed to conventional manufacturing including subtractive manufacturing technologies and formative manufacturing methodologies” [1]. This results in significant advantages over conventional manufacturing methodologies, such as the production of topologically optimized, complex structures, lower material consumption or shorter product development cycles. In order to be able to use these advantages, the possibilities and restrictions of the processes must be known. In particular, selective laser beam melting (SLM), in which a powdery metallic starting material is melted by means of a laser, requires a sound understanding of the process. For this purpose, design guidelines have been presented in various scientific papers. These design guidelines help to design a component in such a way that it can be manufactured successfully using additive manufacturing. These so-called “AMsuitable design guidelines” can be found among others at Adam, Kranz and Thomas [2,3,4,5]. In contrast to established manufacturing processes, the post-processing of additive components is divided into two steps. First, the AM immanent post processing, such as the removing of the component from the building platform or the removing of the remaining powder. These post-processing steps are in the following referred to “post-processing”. Secondly, the subsequent post-processing steps to improve the component properties, such as milling and turning or a stress-relief annealing. These are referred to as “finishing” and form the focus of this paper. With regard to a successful finishing of additively manufactured components, design guidelines must be taken into account that consider the finishing inherent restrictions and possibilities. In the following, these design guidelines are referred to “finishing suitable”. They can deviate significantly from those of conventionally manufactured components in the case of additively manufactured components. Although there are some investigations that deal with the post-processing of additively manufactured components [6,7], there are hardly any design guidelines that are suitable for finishing [8]. Therefore, knowledge about the finishing of additively manufactured components is based on experimental experience rather than on scientific knowledge. For this reason, design guidelines for a finishing suitable design must be methodically determined and quantified. These quantified design guidelines can be used for an automated design check on complex components like topology optimized geometries.}}, author = {{Lammers, Stefan and Tominski, Johannes and Zimmer, Detmar}}, booktitle = {{II International Conference on Simulation for Additive Manufacturing Sim-AM 2019 11-13 September, 2019}}, isbn = {{978-84-949194-8-0}}, pages = {{174--185}}, title = {{{Guidelines for post processing oriented design of additive manufactured parts for use in topology optimization}}}, doi = {{http://congress.cimne.com/sim-am2019/frontal/doc/EbookSim-AM2019.pdf}}, year = {{2019}}, } @inproceedings{21462, abstract = {{This paper presents a new methodology by using a multiple coil array for energy transmission. The complex current strengths of the transmitting coil array are calculated by having the knowledge about of the mutual inductances and the symmetries of the transmitting coil array, so that its resulting magnetic field mainly penetrates only the receiving coil and is strongly attenuated outside. This method is used for an optimized wireless energy transmission but can also be implemented for other inductive applications.}}, author = {{Lange, Sven and Büker, Maik-Julian and Sievers, Denis and Hedayat, Christian and Förstner, Jens and Hilleringmann, Ulrich and Otto, Thomas}}, booktitle = {{Smart Systems Integration; 13th International Conference and Exhibition on Integration Issues of Miniaturized Systems}}, isbn = {{978-3-8007-4919-5}}, keywords = {{tet_enas}}, location = {{Barcelona, Spain }}, pages = {{1--4}}, publisher = {{VDE VERLAG GMBH}}, title = {{{Method of superposing a multiple driven magnetic field to minimize stray fields around the receiver for inductive wireless power transmission}}}, year = {{2019}}, } @misc{58057, author = {{Demenev, A.A. and Yaremkevich, D.D. and Scherbakov, A.V. and Kukhtaruk, S.M. and Gavrilov, S.S. and Yakolev, D.R. and Kulakovskii, V.D. and Bayer, M.}}, booktitle = {{Physical Review B}}, title = {{{Ultrafast strain-induced switching of a bistable cavity-polariton system}}}, year = {{2019}}, } @article{20578, author = {{Driben, R and Ma, Xuekai and Schumacher, Stefan and Meier, Torsten}}, issn = {{0146-9592}}, journal = {{Optics Letters}}, number = {{6}}, pages = {{1327--1330}}, title = {{{Bloch oscillations of multidimensional dark soliton wave packets and light bullets}}}, doi = {{10.1364/ol.44.001327}}, volume = {{44}}, year = {{2019}}, } @article{40384, author = {{Ferreri, Alessandro and Ansari, V. and Silberhorn, Christine and Sharapova, Polina R.}}, issn = {{2469-9926}}, journal = {{Physical Review A}}, number = {{5}}, publisher = {{American Physical Society (APS)}}, title = {{{Temporally multimode four-photon Hong-Ou-Mandel interference}}}, doi = {{10.1103/physreva.100.053829}}, volume = {{100}}, year = {{2019}}, } @article{25304, author = {{Wolk, Andreas and Rosenthal, Marta and Neuhaus, Stephan and Huber, Klaus and Brassat, Katharina and Lindner, Jörg K. N. and Grothe, Richard and Grundmeier, Guido and Bremser, Wolfgang and Wilhelm, René}}, issn = {{2045-2322}}, journal = {{Scientific Reports}}, title = {{{A Novel Lubricant Based on Covalent Functionalized Graphene Oxide Quantum Dots}}}, doi = {{10.1038/s41598-018-24062-2}}, year = {{2018}}, } @article{25305, author = {{Rüdiger, Arne A. and Brassat, Katharina and Lindner, Jörg K. N. and Bremser, Wolfgang and Strube, Oliver I.}}, issn = {{0743-7463}}, journal = {{Langmuir}}, pages = {{4264--4270}}, title = {{{Easily Accessible Protein Nanostructures via Enzyme Mediated Addressing}}}, doi = {{10.1021/acs.langmuir.7b04089}}, year = {{2018}}, } @inproceedings{19868, author = {{Camberg, Alan Adam and Tröster, Thomas and Sotirov, Nikolay and Tölle, Jörn and Bohner, Friedrich}}, booktitle = {{Materials Science and Engineering (MSE) Congress 2018}}, location = {{Darmstadt}}, title = {{{Investigation of ductility and damage characteristics of EN AW-5182 H18 at non-isothermal forming conditions}}}, year = {{2018}}, } @article{20, abstract = {{Approximate computing has shown to provide new ways to improve performance and power consumption of error-resilient applications. While many of these applications can be found in image processing, data classification or machine learning, we demonstrate its suitability to a problem from scientific computing. Utilizing the self-correcting behavior of iterative algorithms, we show that approximate computing can be applied to the calculation of inverse matrix p-th roots which are required in many applications in scientific computing. Results show great opportunities to reduce the computational effort and bandwidth required for the execution of the discussed algorithm, especially when targeting special accelerator hardware.}}, author = {{Lass, Michael and Kühne, Thomas and Plessl, Christian}}, issn = {{1943-0671}}, journal = {{Embedded Systems Letters}}, number = {{2}}, pages = {{ 33--36}}, publisher = {{IEEE}}, title = {{{Using Approximate Computing for the Calculation of Inverse Matrix p-th Roots}}}, doi = {{10.1109/LES.2017.2760923}}, volume = {{10}}, year = {{2018}}, } @misc{28361, author = {{Gausemeier, Jürgen}}, isbn = {{978-3-947647-04-0}}, publisher = {{Verlagsschriftenreihe des Heinz Nixdorf Instituts, Paderborn}}, title = {{{Vorausschau und Technologieplanung. 14. Symposium für Vorausschau und Technologieplanung, Heinz Nixdorf Institut, 8. und 9. November 2018}}}, volume = {{385}}, year = {{2018}}, } @phdthesis{24527, author = {{Hopp, Matthias}}, publisher = {{Shaker Verlag}}, title = {{{Verfahrenstechnische Entwicklung zum Kleben von WPC für Anwendungsgebiete aus dem Holz-/Kunststoffbereich}}}, year = {{2018}}, }