@article{12930, author = {{Köthemann, Ronja and Weber, Nils and Lindner, Jörg K N and Meier, Cedrik}}, issn = {{0268-1242}}, journal = {{Semiconductor Science and Technology}}, number = {{9}}, title = {{{High-precision determination of silicon nanocrystals: optical spectroscopy versus electron microscopy}}}, doi = {{10.1088/1361-6641/ab3536}}, volume = {{34}}, year = {{2019}}, } @article{14990, abstract = {{We investigate optical microresonators consisting of either one or two coupled rectangular strips between upper and lower slab waveguides. The cavities are evanescently excited under oblique angles by thin-film guided, in-plane unguided waves supported by one of the slab waveguides. Beyond a specific incidence angle, losses are fully suppressed. The interaction between the guided mode of the cavity-strip and the incoming slab modes leads to resonant behavior for specific incidence angles and gaps. For a single cavity, at resonance, the input power is equally split among each of the four output ports, while for two cavities an add-drop filter can be realized that, at resonance, routes the incoming power completely to the forward drop waveguide via the cavity. For both applications, the strength of the interaction is controlled by the gaps between cavities and waveguides.}}, author = {{Ebers, Lena and Hammer, Manfred and Berkemeier, Manuel B. and Menzel, Alexander and Förstner, Jens}}, issn = {{2578-7519}}, journal = {{OSA Continuum}}, keywords = {{tet_topic_waveguides}}, pages = {{3288}}, title = {{{Coupled microstrip-cavities under oblique incidence of semi-guided waves: a lossless integrated optical add-drop filter}}}, doi = {{10.1364/osac.2.003288}}, volume = {{2}}, year = {{2019}}, } @misc{7720, abstract = {{Die Erfindung betrifft einen optischen Übergang zwischen zwei optischen Schichtwellenleitern. Dazu ist eine Anordnung vorgesehen aus einem ersten optischen Schichtwellenleiter (2) und einem zweiten optischen Schichtwellenleiter (3), wobei der erste optische Schichtwellenleiter (2) und der zweite optische Schichtwellenleiter (3) voneinander verschiedene über ihre jeweilige Länge konstante Dicken (d, r) aufweisen, der erste optische Schichtwellenleiter (2) mit dem zweiten optischen Schichtwellenleiter (3) mittels einer optischen Schichtwellenleiterstruktur (4) verbunden ist, die über ihre gesamte Länge (w) eine Dicke (h) aufweist, die zwischen der Dicke (d) des ersten optischen Schichtwellenleiters (2) und der Dicke (r) des zweiten optischen Schichtwellenleiters (3) liegt. Erfindungsgemäß ist die Dicke (h) der optischen Schichtwellenleiterstruktur (4) über die gesamte Länge (w) der optischen Schichtwellenleiterstruktur (4) konstant. Damit wird eine Möglichkeit für einen effizienten und mit geringen Verlusten behafteten Übergang zwischen zwei optischen Schichtwellenleitern mit unterschiedlicher Dicke bereitgestellt. }}, author = {{Hammer, Manfred and Förstner, Jens and Ebers, Lena}}, keywords = {{tet_topic_waveguides}}, pages = {{9}}, title = {{{Optical transition between two optical waveguides layer and method for transmitting light}}}, year = {{2019}}, } @article{14544, 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}}, } @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{29746, author = {{Nicholson, C. W. and Puppin, M. and Lücke, A. and Gerstmann, Uwe and Krenz, Marvin and Schmidt, Wolf Gero and Rettig, L. and Ernstorfer, R. and Wolf, M.}}, issn = {{2469-9950}}, journal = {{Physical Review B}}, number = {{15}}, publisher = {{American Physical Society (APS)}}, title = {{{Excited-state band mapping and momentum-resolved ultrafast population dynamics in In/Si(111) nanowires investigated with XUV-based time- and angle-resolved photoemission spectroscopy}}}, doi = {{10.1103/physrevb.99.155107}}, volume = {{99}}, year = {{2019}}, } @article{10015, author = {{Dues, Christof and Schmidt, Wolf Gero and Sanna, Simone}}, issn = {{2470-1343}}, journal = {{ACS Omega}}, pages = {{3850--3859}}, title = {{{Water Splitting Reaction at Polar Lithium Niobate Surfaces}}}, doi = {{10.1021/acsomega.8b03271}}, 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}}, } @inproceedings{13285, author = {{Hannes, Wolf-Rüdiger and Krauß-Kodytek, Laura and Ruppert, Claudia and Betz, Markus and Meier, Torsten}}, booktitle = {{Ultrafast Phenomena and Nanophotonics XXIII}}, editor = {{Betz, Markus and Elezzabi, Abdulhakem Y.}}, isbn = {{9781510624740}}, title = {{{Intensity-dependent degenerate and non-degenerate nonlinear optical absorption of direct-gap semiconductors}}}, doi = {{10.1117/12.2503539}}, volume = {{10916}}, 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{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}}, } @article{13282, author = {{Lin, Zemeng and Huang, Lingling and Xu, Zhen Tao and Li, Xiaowei and Zentgraf, Thomas and Wang, Yongtian}}, issn = {{2195-1071}}, journal = {{Advanced Optical Materials}}, number = {{21}}, pages = {{1900782}}, title = {{{Four‐Wave Mixing Holographic Multiplexing Based on Nonlinear Metasurfaces}}}, doi = {{10.1002/adom.201900782}}, volume = {{7}}, 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{3740, abstract = {{Oblique propagation of semi-guided waves across slab waveguide structures with bent corners is investigated. A critical angle can be defined beyond which all radiation losses are suppressed. Additionally an increase of the curvature radius of the bends also leads to low-loss configurations for incidence angles below that critical angle. A combination of two bent corner systems represents a step-like structure, behaving like a Fabry-Perot interferometer, with two partial reflectors separated by the vertical height between the horizontal slabs. We numerically analyse typical high-index-contrast Si/SiO2 structures for their reflectance and transmittance properties. When increasing the curvature radius the resonant effect becomes less relevant such that full transmittance is reached with less critical conditions on the vertical distance or the incidence angle. For practical interest 3-D problems are considered, where the structures are excited by the fundamental mode of a wide, shallow rib waveguide. High transmittance levels can be observed also for these 3-D configurations depending on the width of the rib.}}, author = {{Ebers, Lena and Hammer, Manfred and Förstner, Jens}}, journal = {{Optics Express}}, keywords = {{tet_topic_waveguide}}, number = {{14}}, pages = {{18621--18632}}, publisher = {{OSA Publishing}}, title = {{{Oblique incidence of semi-guided planar waves on slab waveguide steps: effects of rounded edges}}}, doi = {{10.1364/OE.26.018621}}, volume = {{26}}, year = {{2018}}, } @inproceedings{4579, abstract = {{Semi-guided waves confined in dielectric slab waveguides are being considered for oblique angles of propagation. If the waves encounter a linear discontinuity of (mostly) arbitrary shape and extension, a variant of Snell's law applies, separately for each pair of incoming and outgoing modes. Depending on the effective indices involved, and on the angle of incidence, power transfer to specific outgoing waves can be allowed or forbidden. In particular, critical angles of incidence can be identified, beyond which any power transfer to non-guided waves is forbidden, i.e. all radiative losses are suppressed. In that case the input power is carried away from the discontinuity exclusively by reflected semi-guided waves in the input slab, or by semi-guided waves that are transmitted into other outgoing slab waveguides. Vectorial equations on a 2-D cross sectional domain apply. These are formally identical to the equations that govern the eigenmodes of 3-D channel waveguides. Here, however, these need to be solved not as an eigenvalue problem, but as an inhomogeneous problem with a right-hand-side that is given by the incoming semi-guided wave, and subject to transparent boundary conditions. The equations resemble a standard 2-D Helmholtz problem, with an effective permittivity in place of the actual relative permittivity. Depending on the properties of the incoming wave, including the angle of incidence, this effective permittivity can become locally negative, causing the suppression of propagating outgoing waves. A series of high-contrast example configurations are discussed, where these effects lead to - in some respects - quite surprising transmission characteristics.}}, author = {{Hammer, Manfred and Ebers, Lena and Hildebrandt, Andre and Alhaddad, Samer and Förstner, Jens}}, booktitle = {{2018 IEEE 17th International Conference on Mathematical Methods in Electromagnetic Theory (MMET)}}, isbn = {{9781538654385}}, keywords = {{tet_topic_waveguides}}, publisher = {{IEEE}}, title = {{{Oblique Semi-Guided Waves: 2-D Integrated Photonics with Negative Effective Permittivity}}}, doi = {{10.1109/mmet.2018.8460455}}, year = {{2018}}, }