@article{21547,
  author       = {{Riabinin, Matvei and Sharapova, Polina and Bartley, Tim and Meier, Torsten}},
  issn         = {{2399-6528}},
  journal      = {{Journal of Physics Communications}},
  number       = {{4}},
  title        = {{{Generating two-mode squeezing with multimode measurement-induced nonlinearity}}},
  doi          = {{10.1088/2399-6528/abeec2}},
  volume       = {{5}},
  year         = {{2021}},
}

@article{23472,
  author       = {{Krauss-Kodytek, L. and Hannes, Wolf-Rüdiger and Meier, Torsten and Ruppert, C. and Betz, M.}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  number       = {{8}},
  title        = {{{Nondegenerate two-photon absorption in ZnSe: Experiment and theory}}},
  doi          = {{10.1103/physrevb.104.085201}},
  volume       = {{104}},
  year         = {{2021}},
}

@article{21475,
  author       = {{Frese, Daniel and Wei, Qunshuo and Wang, Yongtian and Cinchetti, Mirko and Huang, Lingling and Zentgraf, Thomas}},
  issn         = {{2330-4022}},
  journal      = {{ACS Photonics}},
  number       = {{4}},
  pages        = {{1013--1019}},
  title        = {{{Nonlinear Bicolor Holography Using Plasmonic Metasurfaces}}},
  doi          = {{10.1021/acsphotonics.1c00028}},
  volume       = {{8}},
  year         = {{2021}},
}

@article{21362,
  author       = {{Xue, Yan and Chestnov, Igor and Sedov, Evgeny and Kiktenko, Evgeniy and Fedorov, Aleksey K. and Schumacher, Stefan and Ma, Xuekai and Kavokin, Alexey}},
  issn         = {{2643-1564}},
  journal      = {{Physical Review Research}},
  number       = {{1}},
  title        = {{{Split-ring polariton condensates as macroscopic two-level quantum systems}}},
  doi          = {{10.1103/physrevresearch.3.013099}},
  volume       = {{3}},
  year         = {{2021}},
}

@article{21359,
  author       = {{Barkhausen, Franziska and Pukrop, Matthias and Schumacher, Stefan and Ma, Xuekai}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  number       = {{7}},
  title        = {{{Structuring coflowing and counterflowing currents of polariton condensates in concentric ring-shaped and elliptical potentials}}},
  doi          = {{10.1103/physrevb.103.075305}},
  volume       = {{103}},
  year         = {{2021}},
}

@article{29747,
  author       = {{Jurgen von Bardeleben, Hans and Cantin, Jean-Louis and Gerstmann, Uwe and Schmidt, Wolf Gero and Biktagirov, Timur}},
  issn         = {{1530-6984}},
  journal      = {{Nano Letters}},
  keywords     = {{Mechanical Engineering, Condensed Matter Physics, General Materials Science, General Chemistry, Bioengineering}},
  number       = {{19}},
  pages        = {{8119--8125}},
  publisher    = {{American Chemical Society (ACS)}},
  title        = {{{Spin Polarization, Electron–Phonon Coupling, and Zero-Phonon Line of the NV Center in 3C-SiC}}},
  doi          = {{10.1021/acs.nanolett.1c02564}},
  volume       = {{21}},
  year         = {{2021}},
}

@article{22010,
  author       = {{Aldahhak, Hazem and Hogan, Conor and Lindner, Susi and Appelfeller, Stephan and Eisele, Holger and Schmidt, Wolf Gero and Dähne, Mario and Gerstmann, Uwe and Franz, Martin}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  pages        = {{035303}},
  title        = {{{Electronic structure of the Si(111)3×3R30∘−B surface from theory and photoemission spectroscopy}}},
  doi          = {{10.1103/physrevb.103.035303}},
  volume       = {{103}},
  year         = {{2021}},
}

@inproceedings{40374,
  abstract     = {{<jats:p>We present a frequency multimode integrated SU (1,1) interferometer with a polarization converter and strong signal-idler photon correlations. Phase sensitivity below the shot noise limit is demonstrated, various filtering and seeding strategies are discussed.</jats:p>}},
  author       = {{Ferreri, A. and Santandrea, Matteo and Stefszky, Michael and Luo, Kai Hong and Herrmann, Harald and Silberhorn, Christine and Sharapova, Polina}},
  booktitle    = {{Conference on Lasers and Electro-Optics}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{Multimode integrated SU(1,1) interferometer}}},
  doi          = {{10.1364/cleo_qels.2021.ftu1n.6}},
  year         = {{2021}},
}

@article{20189,
  abstract     = {{A dielectric step-index optical fiber with tube-like profile is considered, being positioned with a small gap on top of a dielectric slab waveguide. We propose a 2.5-D hybrid analytical/numerical coupled mode model for the evanescent excitation of the tube through semi-guided waves propagating in the slab at oblique angles. The model combines the directional polarized modes supported by the slab with analytic solutions for the TE-, TM-, and orbital-angular-momentum (OAM) modes of the tube-shaped fiber. Implementational details of the scheme are discussed, complemented by finite-element simulations for verification purposes. Our results include configurations with resonant in-fiber excitation of OAM modes with large orbital angular momentum and strong field enhancement.}},
  author       = {{Hammer, Manfred and Ebers, Lena and Förstner, Jens}},
  issn         = {{0306-8919}},
  journal      = {{Optical and Quantum Electronics}},
  keywords     = {{tet_topic_waveguides}},
  title        = {{{Hybrid coupled mode modelling of the evanescent excitation of a dielectric tube by semi-guided waves at oblique angles}}},
  doi          = {{10.1007/s11082-020-02595-z}},
  volume       = {{52}},
  year         = {{2020}},
}

@article{20372,
  abstract     = {{A stepwise angular spectrum method (SASM) for curved interfaces is presented to calculate the wave propagation in planar lens-like integrated optical structures based on photonic slab waveguides. The method is derived and illustrated for an effective 2D setup first and then for 3D slab waveguide lenses. We employ slab waveguides of different thicknesses connected by curved surfaces to realize a lens-like structure. To simulate the wave propagation in 3D including reflection and scattering losses, the stepwise angular spectrum method is combined with full vectorial finite element computations for subproblems with lower complexity. Our SASM results show excellent agreement with rigorous numerical simulations of the full structures with a substantially lower computational effort and can be utilized for the simulation-based design and optimization of complex and large scale setups.}},
  author       = {{Ebers, Lena and Hammer, Manfred and Förstner, Jens}},
  issn         = {{1094-4087}},
  journal      = {{Optics Express}},
  keywords     = {{tet_topic_waveguides}},
  number       = {{24}},
  pages        = {{36361}},
  title        = {{{Light diffraction in slab waveguide lenses simulated with the stepwise angular spectrum method}}},
  doi          = {{10.1364/oe.409612}},
  volume       = {{28}},
  year         = {{2020}},
}

@article{20644,
  abstract     = {{Plasmonic nanoantennas for visible and infrared radiation strongly improve the interaction of light with the matter on the nanoscale due to their strong near-field enhancement. In this study, we investigate a double-resonant plasmonic nanoantenna, which makes use of plasmonic field enhancement, enhanced outcoupling of second harmonic light, and resonant lattice effects. Using this design, we demonstrate how the efficiency of second harmonic generation can be increased significantly by fully embedding the nanoantennas into nonlinear dielectric material ZnO, instead of placing them on the surface. Investigating two different processes, we found that the best fabrication route is embedding the gold nanoantennas in ZnO using an MBE overgrowth process where a thin ZnO layer was deposited on nanoantennas fabricated on a ZnO substrate. In addition, second harmonic generation measurements show that the embedding leads to an enhancement compared to the emission of nanoantennas placed on the ZnO substrate surface. These promising results facilitate further research to determine the influence of the periodicity of the nanoantenna arrangement of the resulting SHG signal.}},
  author       = {{Volmert, Ruth and Weber, Nils and Meier, Cedrik}},
  issn         = {{1089-7550}},
  journal      = {{Journal of Applied Physics}},
  number       = {{4}},
  title        = {{{Nanoantennas embedded in zinc oxide for second harmonic generation enhancement}}},
  doi          = {{10.1063/5.0012813}},
  volume       = {{128}},
  year         = {{2020}},
}

@inbook{20847,
  author       = {{Zentgraf, Thomas and Chen, Shumei and Li, Guixin and Zhang, Shuang}},
  booktitle    = {{Nanoantennas and Plasmonics: Modelling, design and fabrication}},
  editor       = {{Werner, Douglas H. and Campbell, Sawyer D. and Kang, Lei}},
  publisher    = {{The Institution of Engineering and Technology}},
  title        = {{{Plasmonic metasurfaces for controlling harmonic generations}}},
  doi          = {{10.1049/SBEW540E_ch8}},
  year         = {{2020}},
}

@article{16944,
  author       = {{Schlickriede, Christian and Kruk, Sergey S. and Wang, Lei and Sain, Basudeb and Kivshar, Yuri and Zentgraf, Thomas}},
  issn         = {{1530-6984}},
  journal      = {{Nano Letters}},
  number       = {{6}},
  pages        = {{4370–4376}},
  title        = {{{Nonlinear imaging with all-dielectric metasurfaces}}},
  doi          = {{10.1021/acs.nanolett.0c01105}},
  volume       = {{20}},
  year         = {{2020}},
}

@article{16197,
  abstract     = {{Nonlinear Pancharatnam–Berry phase metasurfaces facilitate the nontrivial phase modulation for frequency conversion processes by leveraging photon‐spin dependent nonlinear geometric‐phases. However, plasmonic metasurfaces show some severe limitation for nonlinear frequency conversion due to the intrinsic high ohmic loss and low damage threshold of plasmonic nanostructures. Here, the nonlinear geometric‐phases associated with the third‐harmonic generation process occurring in all‐dielectric metasurfaces is studied systematically, which are composed of silicon nanofins with different in‐plane rotational symmetries. It is found that the wave coupling among different field components of the resonant fundamental field gives rise to the appearance of different nonlinear geometric‐phases of the generated third‐harmonic signals. The experimental observations of the nonlinear beam steering and nonlinear holography realized in this work by all‐dielectric geometric‐phase metasurfaces are well explained with the developed theory. This work offers a new physical picture to understand the nonlinear optical process occurring at nanoscale dielectric resonators and will help in the design of nonlinear metasurfaces with tailored phase properties.}},
  author       = {{Liu, Bingyi and Sain, Basudeb and Reineke, Bernhard and Zhao, Ruizhe and Meier, Cedrik and Huang, Lingling and Jiang, Yongyuan and Zentgraf, Thomas}},
  issn         = {{2195-1071}},
  journal      = {{Advanced Optical Materials}},
  number       = {{9}},
  publisher    = {{Wiley}},
  title        = {{{Nonlinear Wavefront Control by Geometric-Phase Dielectric Metasurfaces: Influence of Mode Field and Rotational Symmetry}}},
  doi          = {{10.1002/adom.201902050}},
  volume       = {{8}},
  year         = {{2020}},
}

@article{17322,
  author       = {{Mukherjee, Amlan and Widhalm, Alex and Siebert, Dustin and Krehs, Sebastian and Sharma, Nandlal and Thiede, Andreas and Reuter, Dirk and Förstner, Jens and Zrenner, Artur}},
  issn         = {{0003-6951}},
  journal      = {{Applied Physics Letters}},
  keywords     = {{tet_topic_qd}},
  pages        = {{251103}},
  title        = {{{Electrically controlled rapid adiabatic passage in a single quantum dot}}},
  doi          = {{10.1063/5.0012257}},
  volume       = {{116}},
  year         = {{2020}},
}

@article{17067,
  author       = {{Speiser, Eugen and Esser, Norbert and Halbig, Benedikt and Geurts, Jean and Schmidt, Wolf Gero and Sanna, Simone}},
  issn         = {{0167-5729}},
  journal      = {{Surface Science Reports}},
  number       = {{1}},
  title        = {{{Vibrational Raman spectroscopy on adsorbate-induced low-dimensional surface structures}}},
  doi          = {{10.1016/j.surfrep.2020.100480}},
  volume       = {{75}},
  year         = {{2020}},
}

@article{20582,
  author       = {{Berger, Bernd and Schmidt, Daniel and Ma, Xuekai and Schumacher, Stefan and Schneider, Christian and Höfling, Sven and Assmann, Marc}},
  journal      = {{Physical Review B}},
  number       = {{24}},
  pages        = {{245309}},
  publisher    = {{American Physical Society}},
  title        = {{{Formation dynamics of exciton-polariton vortices created by nonresonant annular pumping}}},
  doi          = {{10.1103/PhysRevB.101.245309}},
  volume       = {{101}},
  year         = {{2020}},
}

@article{19190,
  abstract     = {{Polarons in dielectric crystals play a crucial role for applications in integrated electronics and optoelectronics. In this work, we use density-functional theory and Green's function methods to explore the microscopic structure and spectroscopic signatures of electron polarons in lithium niobate (LiNbO3). Total-energy calculations and the comparison of calculated electron paramagnetic resonance data with available measurements reveal the formation of bound 
polarons at Nb_Li antisite defects with a quasi-Jahn-Teller distorted, tilted configuration. The defect-formation energies further indicate that (bi)polarons may form not only at 
Nb_Li antisites but also at structures where the antisite Nb atom moves into a neighboring empty oxygen octahedron. Based on these structure models, and on the calculated charge-transition levels and potential-energy barriers, we propose two mechanisms for the optical and thermal splitting of bipolarons, which provide a natural explanation for the reported two-path recombination of bipolarons. Optical-response calculations based on the Bethe-Salpeter equation, in combination with available experimental data and new measurements of the optical absorption spectrum, further corroborate the geometries proposed here for free and defect-bound (bi)polarons.}},
  author       = {{Schmidt, Falko and Kozub, Agnieszka L. and Biktagirov, Timur and Eigner, Christof and Silberhorn, Christine and Schindlmayr, Arno and Schmidt, Wolf Gero and Gerstmann, Uwe}},
  issn         = {{2643-1564}},
  journal      = {{Physical Review Research}},
  number       = {{4}},
  publisher    = {{American Physical Society}},
  title        = {{{Free and defect-bound (bi)polarons in LiNbO3: Atomic structure and spectroscopic signatures from ab initio calculations}}},
  doi          = {{10.1103/PhysRevResearch.2.043002}},
  volume       = {{2}},
  year         = {{2020}},
}

@article{40444,
  author       = {{von Bardeleben, H. J. and Rauls, E. and Gerstmann, Uwe}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  number       = {{18}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Carbon vacancy-related centers in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mn>3</mml:mn><mml:mi>C</mml:mi></mml:math>-silicon carbide: Negative-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>U</mml:mi></mml:math> properties and structural transformation}}},
  doi          = {{10.1103/physrevb.101.184108}},
  volume       = {{101}},
  year         = {{2020}},
}

@article{20773,
  abstract     = {{<jats:title>Abstract</jats:title><jats:p>Semiconductor quantum dots are excellent candidates for ultrafast coherent manipulation of qubits by laser pulses on picosecond timescales or even faster. In inhomogeneous ensembles a macroscopic optical polarization decays rapidly due to dephasing, which, however, is reversible in photon echoes carrying complete information about the coherent ensemble dynamics. Control of the echo emission time is mandatory for applications. Here, we propose a concept to reach this goal. In a two-pulse photon echo sequence, we apply an additional resonant control pulse with multiple of 2<jats:italic>π</jats:italic> area. Depending on its arrival time, the control slows down dephasing or rephasing of the exciton ensemble during its action. We demonstrate for self-assembled (In,Ga)As quantum dots that the photon echo emission time can be retarded or advanced by up to 5 ps relative to its nominal appearance time without control. This versatile protocol may be used to obtain significantly longer temporal shifts for suitably tailored control pulses.</jats:p>}},
  author       = {{Kosarev, Alexander N. and Rose, Hendrik and Poltavtsev, Sergey V. and Reichelt, Matthias and Schneider, Christian and Kamp, Martin and Höfling, Sven and Bayer, Manfred and Meier, Torsten and Akimov, Ilya A.}},
  issn         = {{2399-3650}},
  journal      = {{Communications Physics}},
  number       = {{1}},
  title        = {{{Accurate photon echo timing by optical freezing of exciton dephasing and rephasing in quantum dots}}},
  doi          = {{10.1038/s42005-020-00491-2}},
  volume       = {{3}},
  year         = {{2020}},
}