@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}}, } @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{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}}, } @article{4831, abstract = {{Polarization of light is essential for some living organisms and many optical applications. Here, an orientation dependent polarization conversion effect is reported for light reflected from diamond‐structure‐based photonic crystals (D‐structure) inside the scales of a beetle, the weevil Entimus imperialis. When linearly polarized light propagates along its 〈100〉 directions, the D‐structure behaves analogous to a half‐wave plate in reflection but based on a different mechanism. The D‐structure rotates the polarization direction of linearly polarized light, and reflects circularly polarized light of both handednesses without changing it. This polarization effect is different from circular dichroism occurring in chiral biological photonic structures discovered before. The structural origin of this effect is symmetry breaking inside D‐structure's unit cell. This finding demonstrates that natural photonic structures can exploit multiple functionalities inherent to the design principles of their structural organization. Aiming at transferring the inherent polarization effect of the biological D‐structure to technically realizable materials, three simplified biomimetic structural models are derived and it is theoretically demonstrated that they retain the effect. Out of these structures, functioning woodpile structure prototypes are fabricated.}}, author = {{Wu, Xia and Rodríguez-Gallegos, Fernando L. and Heep, Marie-Christin and Schwind, Bertram and Li, Guixin and Fabritius, Helge-Otto and von Freymann, Georg and Förstner, Jens}}, issn = {{2195-1071}}, journal = {{Advanced Optical Materials}}, keywords = {{tet_topic_phc, tet_topic_bio}}, number = {{24}}, pages = {{1800635}}, publisher = {{Wiley}}, title = {{{Polarization Conversion Effect in Biological and Synthetic Photonic Diamond Structures}}}, doi = {{10.1002/adom.201800635}}, volume = {{6}}, year = {{2018}}, } @article{4165, abstract = {{Metal nanoparticles host localized plasmon excitations that allow the manipulation of optical fields at the nanoscale. Despite the availability of several techniques for imaging plasmons, direct access into the symmetries of these excitations remains elusive, thus hindering progress in the development of applications. Here, we present a combination of angle-, polarization-, and space-resolved cathodoluminescence spectroscopy methods to selectively access the symmetry and degeneracy of plasmonic states in lithographically fabricated gold nanoprisms. We experimentally reveal and spatially map degenerate states of multipole plasmon modes with nanometer spatial resolution and further provide recipes for resolving optically dark and out-of-plane modes. Full-wave simulations in conjunction with a simple tight-binding model explain the complex plasmon structure in these particles and reveal intriguing mode-symmetry phenomena. Our approach introduces systematics for a comprehensive symmetry characterization of plasmonic states in high-symmetry nanostructures.}}, author = {{Myroshnychenko, Viktor and Nishio, Natsuki and García de Abajo, F. Javier and Förstner, Jens and Yamamoto, Naoki}}, issn = {{1936-0851}}, journal = {{ACS Nano}}, keywords = {{tet_topic_plasmonics}}, number = {{8}}, pages = {{8436--8446}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Unveiling and Imaging Degenerate States in Plasmonic Nanoparticles with Nanometer Resolution}}}, doi = {{10.1021/acsnano.8b03926}}, volume = {{12}}, year = {{2018}}, } @article{4342, author = {{Chen, Shumei and Rahmani, Mohsen and Li, King Fai and Miroshnichenko, Andrey and Zentgraf, Thomas and Li, Guixin and Neshev, Dragomir and Zhang, Shuang}}, issn = {{2330-4022}}, journal = {{ACS Photonics}}, number = {{5}}, pages = {{1671--1675}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Third Harmonic Generation Enhanced by Multipolar Interference in Complementary Silicon Metasurfaces}}}, doi = {{10.1021/acsphotonics.7b01423}}, volume = {{5}}, year = {{2018}}, } @article{1430, author = {{Hoffmann, Sandro P. and Albert, Maximilian and Weber, Nils and Sievers, Denis and Förstner, Jens and Zentgraf, Thomas and Meier, Cedrik}}, issn = {{2330-4022}}, journal = {{ACS Photonics}}, keywords = {{tet_topic_phc}}, pages = {{1933--1942}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Tailored UV Emission by Nonlinear IR Excitation from ZnO Photonic Crystal Nanocavities}}}, doi = {{10.1021/acsphotonics.7b01228}}, volume = {{5}}, year = {{2018}}, } @article{1327, author = {{Weber, N. and Hoffmann, S. P. and Albert, M. and Zentgraf, Thomas and Meier, Cedrik}}, issn = {{0021-8979}}, journal = {{Journal of Applied Physics}}, number = {{10}}, publisher = {{AIP Publishing}}, title = {{{Efficient frequency conversion by combined photonic–plasmonic mode coupling}}}, doi = {{10.1063/1.5017010}}, volume = {{123}}, year = {{2018}}, } @article{10013, abstract = {{Ultrafast nonequilibrium dynamics offer a route to study the microscopic interactions that govern macroscopic behavior. In particular, photoinduced phase transitions (PIPTs) in solids provide a test case for how forces, and the resulting atomic motion along a reaction coordinate, originate from a nonequilibrium population of excited electronic states. Using femtosecond photoemission, we obtain access to the transient electronic structure during an ultrafast PIPT in a model system: indium nanowires on a silicon(111) surface. We uncover a detailed reaction pathway, allowing a direct comparison with the dynamics predicted by ab initio simulations. This further reveals the crucial role played by localized photoholes in shaping the potential energy landscape and enables a combined momentum- and real-space description of PIPTs, including the ultrafast formation of chemical bonds.}}, author = {{Nicholson, C. W. and Lücke, A. and Schmidt, Wolf Gero and Puppin, M. and Rettig, L. and Ernstorfer, R. and Wolf, M.}}, issn = {{0036-8075}}, journal = {{Science}}, pages = {{821--825}}, title = {{{Beyond the molecular movie: Dynamics of bands and bonds during a photoinduced phase transition}}}, doi = {{10.1126/science.aar4183}}, year = {{2018}}, } @article{10016, author = {{Paszkiewicz, Mateusz and Biktagirov, Timur and Aldahhak, Hazem and Allegretti, Francesco and Rauls, Eva and Schöfberger, Wolfgang and Schmidt, Wolf Gero and Barth, Johannes V. and Gerstmann, Uwe and Klappenberger, Florian}}, issn = {{1948-7185}}, journal = {{The Journal of Physical Chemistry Letters}}, pages = {{6412--6420}}, title = {{{Unraveling the Oxidation and Spin State of Mn–Corrole through X-ray Spectroscopy and Quantum Chemical Analysis}}}, doi = {{10.1021/acs.jpclett.8b02525}}, year = {{2018}}, }