@article{7221, author = {{Chen, J. C. H. and Klochan, O. and Micolich, A. P. and Das Gupta, K. and Sfigakis, F. and Ritchie, D. A. and Trunov, K. and Reuter, Dirk and Wieck, A. D. and Hamilton, A. R.}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, number = {{18}}, publisher = {{AIP Publishing}}, title = {{{Fabrication and characterisation of gallium arsenide ambipolar quantum point contacts}}}, doi = {{10.1063/1.4918934}}, volume = {{106}}, year = {{2015}}, } @article{7222, author = {{Finke, A. and Ruth, M. and Scholz, S. and Ludwig, A. and Wieck, A. D. and Reuter, Dirk and Pawlis, A.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, number = {{3}}, publisher = {{American Physical Society (APS)}}, title = {{{Extending the spectral range of CdSe/ZnSe quantum wells by strain engineering}}}, doi = {{10.1103/physrevb.91.035409}}, volume = {{91}}, year = {{2015}}, } @article{4276, abstract = {{We analyse an InAs/GaAs-based electric field tunable single quantum dot diode with a thin tunnelling barrier between a buried n þ -back contact and a quantum dot layer. In voltage- dependent photoluminescence measurements, we observe rich signatures from spatially direct and indirect transitions from the wetting layer and from a single quantum dot. By analysing the Stark effect, we show that the indirect transitions result from a recombination between confined holes in the wetting or quantum dot layer with electrons from the edge of the Fermi sea in the back contact. Using a 17 nm tunnel barrier which provides comparably weak tunnel coupling allowed us to observe clear signatures of direct and corresponding indirect lines for a series of neutral and positively charged quantum dot states.}}, author = {{Rai, Ashish K. and Gordon, Simon and Ludwig, Arne and Wieck, Andreas D. and Zrenner, Artur and Reuter, Dirk}}, issn = {{0370-1972}}, journal = {{physica status solidi (b)}}, keywords = {{excitons, GaAs, InAs, quantum dots, spatially indirect transitions, Stark shift}}, number = {{3}}, pages = {{437--441}}, publisher = {{Wiley}}, title = {{{Spatially indirect transitions in electric field tunable quantum dot diodes}}}, doi = {{10.1002/pssb.201552591}}, volume = {{253}}, year = {{2015}}, } @article{4331, abstract = {{We report about the fabrication and analysis of high Q photonic crystal cavities with metallic Schottky-contacts. The structures are based on GaAs n-i membranes with an InGaAs quantum well in the i-region and nanostructured low ohmic metal top-gates. They are designed for photocurrent readout within the cavity and fast electric manipulations. The cavity structures are characterized by photoluminescence and photocurrent spectroscopy under resonant excitation. We find strong cavity resonances in the photocurrent spectra and surprisingly high Q-factors up to 6500. Temperature dependent photocurrent measurements in the region between 4.5K and 310K show an exponential enhancement of the photocurrent signal and an external quantum efficiency up to 0.26.}}, author = {{Quiring, W. and Al-Hmoud, M. and Rai, A. and Reuter, Dirk and Wieck, A. D. and Zrenner, Artur}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, number = {{4}}, publisher = {{AIP Publishing}}, title = {{{Photonic crystal cavities with metallic Schottky contacts}}}, doi = {{10.1063/1.4928038}}, volume = {{107}}, year = {{2015}}, } @misc{5413, author = {{Funke, Lukas}}, publisher = {{Universität Paderborn}}, title = {{{An LLVM Based Toolchain for Transparent Acceleration of Digital Image Processing Applications using FPGA Overlay Architectures}}}, year = {{2015}}, } @misc{5416, author = {{Löcke, Thomas}}, publisher = {{Universität Paderborn}}, title = {{{Instance-Specific Computing in Hard- and Software for Faster Solving of Complex Problems}}}, year = {{2015}}, } @misc{5419, author = {{Wallaschek, Felix}}, publisher = {{Universität Paderborn}}, title = {{{Accelerating Programmable Logic Controllers with the use of FPGAs}}}, year = {{2015}}, } @article{6520, abstract = {{We investigate the response of a polariton laser driven slightly off-resonantly using light fields differing from the routinely studied coherent pump sources. The response to driving light fields with thermal and displaced thermal statistics with varying correlation times shows significant differences in the transmitted intensity, its noise, and the position of the nonlinear threshold. We predict that adding more photons on average may actually reduce the transmission through the polariton system.}}, author = {{Assmann, Marc and Bayer, Manfred}}, issn = {{1050-2947}}, journal = {{PHYSICAL REVIEW A}}, number = {{5}}, title = {{{Stochastic pumping of a polariton fluid}}}, doi = {{10.1103/PhysRevA.91.053835}}, volume = {{91}}, year = {{2015}}, } @article{6522, abstract = {{An electric field applied to a semiconductor reduces its crystal symmetry and modifies its electronic structure which is expected to result in changes of the linear and nonlinear response to optical excitation. In GaAs, we observe experimentally strong electric field effects on the optical second (SHG) and third (THG) harmonic generation. The SHG signal for the laser-light k vector parallel to the [001] crystal axis is symmetry forbidden in the electric-dipole approximation, but can be induced by an applied electric field in the vicinity of the 1s exciton energy. Surprisingly, the THG signal, which is allowed in this geometry, is considerably reduced by the electric field. We develop a theory which provides good agreement with the experimental data. In particular, it shows that the optical nonlinearities for the 1s exciton resonance are modified in an electric field by the Stark effect, which mixes the 1s and 2p exciton states of opposite parity. This mixing acts in opposite way on the SHG and THG processes, as it leads to the appearance of forbidden SHG in (001)-oriented GaAs and decreases the crystallographic THG.}}, author = {{Brunne, D. and Lafrentz, M. and Pavlov, V. V. and Pisarev, R. V. and Rodina, A. V. and Yakovlev, D. R. and Bayer, M.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, number = {{8}}, publisher = {{American Physical Society (APS)}}, title = {{{Electric field effect on optical harmonic generation at the exciton resonances in GaAs}}}, doi = {{10.1103/physrevb.92.085202}}, volume = {{92}}, year = {{2015}}, } @article{6524, abstract = {{We use a picosecond acoustics technique to modulate the laser output of electrically pumped GaAs/AlAs micropillar lasers with InGaAs quantum dots. The modulation of the emission wavelength takes place on the frequencies of the nanomechanical extensional and breathing (radial) modes of the micropillars. The amplitude of the modulation for various nanomechanical modes is different for every micropillar which is explained by a various elastic contact between the micropillar walls and polymer environment.}}, author = {{Czerniuk, T. and Tepper, J. and Akimov, A. V. and Unsleber, S. and Schneider, C. and Kamp, M. and Höfling, S. and Yakovlev, D. R. and Bayer, M.}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, number = {{4}}, publisher = {{AIP Publishing}}, title = {{{Impact of nanomechanical resonances on lasing from electrically pumped quantum dot micropillars}}}, doi = {{10.1063/1.4906611}}, volume = {{106}}, year = {{2015}}, } @article{6526, abstract = {{We introduce photon-statistics excitation spectroscopy and exemplarily apply it to a quantum-dot micropillar laser. Both the intensity and the photon number statistics of the emission from the micropillar show a strong dependence on the photon statistics of the light used for excitation of the sample. The results under coherent and pseudothermal excitation reveal that a description of the laser properties in terms of mean input photon numbers is not sufficient. It is demonstrated that the micropillar acts as a superthermal light source when operated close to its threshold. Possible applications for important spectroscopic techniques are discussed.}}, author = {{Kazimierczuk, T. and Schmutzler, J. and Aßmann, M. and Schneider, C. and Kamp, M. and Höfling, S. and Bayer, M.}}, issn = {{0031-9007}}, journal = {{Physical Review Letters}}, number = {{2}}, publisher = {{American Physical Society (APS)}}, title = {{{Photon-Statistics Excitation Spectroscopy of a Quantum-Dot Micropillar Laser}}}, doi = {{10.1103/physrevlett.115.027401}}, volume = {{115}}, year = {{2015}}, } @inproceedings{6529, author = {{Yakovlev, D. R. and Warkentin, W. and Brunne, D. and Mund, J. and Pavlov, V. V. and Rodina, A. V. and Pisarev, R. V. and Bayer, M.}}, booktitle = {{Nonlinear Optics and Applications IX}}, editor = {{Bertolotti, Mario and Haus, Joseph W. and Zheltikov, Alexei M.}}, location = {{Prague, Czech Rep}}, publisher = {{SPIE}}, title = {{{Novel mechanisms of optical harmonic generation on excitons in semiconductors}}}, doi = {{10.1117/12.2185309}}, year = {{2015}}, } @article{1696, author = {{Bader, Christina A. and Zeuner, Franziska and Bader, Manuel H. W. and Zentgraf, Thomas and Meier, Cedrik}}, issn = {{0021-8979}}, journal = {{Journal of Applied Physics}}, number = {{21}}, publisher = {{AIP Publishing}}, title = {{{Nonlinear optical sub-bandgap excitation of ZnO-based photonic resonators}}}, doi = {{10.1063/1.4936768}}, volume = {{118}}, year = {{2015}}, } @article{1698, author = {{Huang, Lingling and Mühlenbernd, Holger and Li, Xiaowei and Song, Xu and Bai, Benfeng and Wang, Yongtian and Zentgraf, Thomas}}, issn = {{0935-9648}}, journal = {{Advanced Materials}}, number = {{41}}, pages = {{6444--6449}}, publisher = {{Wiley-Blackwell}}, title = {{{Broadband Hybrid Holographic Multiplexing with Geometric Metasurfaces}}}, doi = {{10.1002/adma.201502541}}, volume = {{27}}, year = {{2015}}, } @article{1700, author = {{Zheng, Guoxing and Mühlenbernd, Holger and Kenney, Mitchell and Li, Guixin and Zentgraf, Thomas and Zhang, Shuang}}, issn = {{1748-3387}}, journal = {{Nature Nanotechnology}}, number = {{4}}, pages = {{308--312}}, publisher = {{Springer Nature}}, title = {{{Metasurface holograms reaching 80% efficiency}}}, doi = {{10.1038/nnano.2015.2}}, volume = {{10}}, year = {{2015}}, } @phdthesis{10624, abstract = {{The use of heterogeneous computing resources, such as graphics processing units or other specialized co-processors, has become widespread in recent years because of their performance and energy efficiency advantages. Operating system approaches that are limited to optimizing CPU usage are no longer sufficient for the efficient utilization of systems that comprise diverse resource types. Enabling task preemption on these architectures and migration of tasks between different resource types at run-time is not only key to improving the performance and energy consumption but also to enabling automatic scheduling methods for heterogeneous compute nodes. This thesis proposes novel techniques for run-time management of heterogeneous resources and enabling tasks to migrate between diverse hardware. It provides fundamental work towards future operating systems by discussing implications, limitations, and chances of the heterogeneity and introducing solutions for energy- and performance-efficient run-time systems. Scheduling methods to utilize heterogeneous systems by the use of a centralized scheduler are presented that show benefits over existing approaches in varying case studies.}}, author = {{Beisel, Tobias}}, isbn = {{978-3-8325-4155-2}}, pages = {{183}}, publisher = {{Logos Verlag Berlin GmbH}}, title = {{{Management and Scheduling of Accelerators for Heterogeneous High-Performance Computing}}}, year = {{2015}}, } @article{12934, author = {{Röwenstrunk, Daniel and Prätzlich, Thomas and Betzwieser, Thomas and Müller, Meinard and Szwillus, Gerd and Veit, Joachim}}, issn = {{1618-2162}}, journal = {{Datenbank-Spektrum}}, pages = {{65--72}}, title = {{{Das Gesamtkunstwerk Oper aus Datensicht}}}, doi = {{10.1007/s13222-015-0179-0}}, year = {{2015}}, } @article{1461, author = {{Mühlenbernd, Holger and Georgi, Philip and Pholchai, Nitipat and Huang, Lingling and Li, Guixin and Zhang, Shuang and Zentgraf, Thomas}}, issn = {{2330-4022}}, journal = {{ACS Photonics}}, number = {{1}}, pages = {{124--129}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Amplitude- and Phase-Controlled Surface Plasmon Polariton Excitation with Metasurfaces}}}, doi = {{10.1021/acsphotonics.5b00536}}, volume = {{3}}, year = {{2015}}, } @article{15964, author = {{Leuders, Stefan and Vollmer, Malte and Brenne, Florian and Tröster, Thomas and Niendorf, Thomas}}, issn = {{1073-5623}}, journal = {{Metallurgical and Materials Transactions A}}, pages = {{3816--3823}}, title = {{{Fatigue Strength Prediction for Titanium Alloy TiAl6V4 Manufactured by Selective Laser Melting}}}, doi = {{10.1007/s11661-015-2864-x}}, year = {{2015}}, } @inproceedings{16132, author = {{Weiß Borkowski, Nathalie and Marten, Thorsten and Block, Holger and Tröster, Thomas}}, location = {{Toronto, Canada}}, title = {{{Multi-axial Material Testing at High Strain Rates in High Speed Cupping Tests}}}, year = {{2015}}, }