@article{27099,
  abstract     = {{In our work, we have engineered low capacitance single quantum dot photodiodes as sensor devices for the optoelectronic sampling of ultrafast electric signals. By the Stark effect, a time-dependent electric signal is converted into a time-dependent shift of the transition energy. This shift is measured accurately by resonant ps laser spectroscopy with photocurrent detection. In our experiments, we sample the laser synchronous output pulse of an ultrafast CMOS circuit with high resolution. With our quantum dot sensor device, we were able to sample transients below 20 ps with a voltage resolution in the mV-range.}},
  author       = {{Widhalm, Alex and Krehs, Sebastian and Siebert, Dustin and Sharma, Nand Lal and Langer, Timo and Jonas, Björn and Reuter, Dirk and Thiede, Andreas and Förstner, Jens and Zrenner, Artur}},
  issn         = {{0003-6951}},
  journal      = {{Applied Physics Letters}},
  keywords     = {{tet_topic_qd}},
  pages        = {{181109}},
  title        = {{{Optoelectronic sampling of ultrafast electric transients with single quantum dots}}},
  doi          = {{10.1063/5.0061358}},
  volume       = {{119}},
  year         = {{2021}},
}

@article{23816,
  abstract     = {{Employing the ultrafast control of electronic states of a semiconductor quantum dot in a cavity, we introduce an approach to achieve on-demand emission of single photons with almost perfect indistinguishability and photon pairs with near ideal entanglement. Our scheme is based on optical excitation off resonant to a cavity mode followed by ultrafast control of the electronic states using the time-dependent quantum-confined Stark effect, which then allows for cavity-resonant emission. Our theoretical analysis considers cavity-loss mechanisms, the Stark effect, and phonon-induced dephasing, allowing realistic predictions for finite temperatures.}},
  author       = {{Bauch, David and Heinze, Dirk Florian and Förstner, Jens and Jöns, Klaus and Schumacher, Stefan}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  keywords     = {{tet_topic_qd}},
  pages        = {{085308}},
  title        = {{{Ultrafast electric control of cavity mediated single-photon and photon-pair generation with semiconductor quantum dots}}},
  doi          = {{10.1103/physrevb.104.085308}},
  volume       = {{104}},
  year         = {{2021}},
}

@inbook{21587,
  abstract     = {{Solving partial differential equations on unstructured grids is a cornerstone of engineering and scientific computing. Nowadays, heterogeneous parallel platforms with CPUs, GPUs, and FPGAs enable energy-efficient and computationally demanding simulations. We developed the HighPerMeshes C++-embedded Domain-Specific Language (DSL) for bridging the abstraction gap between the mathematical and algorithmic formulation of mesh-based algorithms for PDE problems on the one hand and an increasing number of heterogeneous platforms with their different parallel programming and runtime models on the other hand. Thus, the HighPerMeshes DSL aims at higher productivity in the code development process for multiple target platforms. We introduce the concepts as well as the basic structure of the HighPerMeshes DSL, and demonstrate its usage with three examples, a Poisson and monodomain problem, respectively, solved by the continuous finite element method, and the discontinuous Galerkin method for Maxwell’s equation. The mapping of the abstract algorithmic description onto parallel hardware, including distributed memory compute clusters, is presented. Finally, the achievable performance and scalability are demonstrated for a typical example problem on a multi-core CPU cluster.}},
  author       = {{Alhaddad, Samer and Förstner, Jens and Groth, Stefan and Grünewald, Daniel and Grynko, Yevgen and Hannig, Frank and Kenter, Tobias and Pfreundt, Franz-Josef and Plessl, Christian and Schotte, Merlind and Steinke, Thomas and Teich, Jürgen and Weiser, Martin and Wende, Florian}},
  booktitle    = {{Euro-Par 2020: Parallel Processing Workshops}},
  isbn         = {{9783030715922}},
  issn         = {{0302-9743}},
  keywords     = {{tet_topic_hpc}},
  title        = {{{HighPerMeshes – A Domain-Specific Language for Numerical Algorithms on Unstructured Grids}}},
  doi          = {{10.1007/978-3-030-71593-9_15}},
  year         = {{2021}},
}

@article{24788,
  author       = {{Alhaddad, Samer and Förstner, Jens and Groth, Stefan and Grünewald, Daniel and Grynko, Yevgen and Hannig, Frank and Kenter, Tobias and Pfreundt, Franz‐Josef and Plessl, Christian and Schotte, Merlind and Steinke, Thomas and Teich, Jürgen and Weiser, Martin and Wende, Florian}},
  issn         = {{1532-0626}},
  journal      = {{Concurrency and Computation: Practice and Experience}},
  keywords     = {{tet_topic_hpc}},
  pages        = {{e6616}},
  title        = {{{The HighPerMeshes framework for numerical algorithms on unstructured grids}}},
  doi          = {{10.1002/cpe.6616}},
  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{20233,
  abstract     = {{The challenge of designing new tunable nonlinear dielectric materials with tailored properties has attracted an increasing amount of interest recently. Herein, we study the effective nonlinear dielectric response of a stochastic paraelectric-dielectric composite consisting of equilibrium distributions of circular and partially penetrable disks (or parallel, infinitely long, identical, partially penetrable, circular cylinders) of a dielectric phase randomly dispersed in a continuous matrix of a paraelectric phase. The random microstructures were generated using the Metropolis Monte Carlo algorithm. The evaluation of the effective permittivity and tunability were carried out by employing either a Landau thermodynamic model or its Johnson’s approximation to describe the field-dependent permittivity of the paraelectric phase and solving continuum-electrostatics equations using finite element calculations. We reveal that the percolation threshold in this composite governs the critical behavior of the effective permittivity and tunability. For microstructures below the percolation threshold, our simulations demonstrate a strong nonlinear behaviour of the field-dependent effective permittivity and very high tunability that increases as a function of dielectric phase concentration. Above the percolation threshold, the effective permittivity shows the tendency to linearization and the tunability dramatically drops down. The highly reduced permittivity and extraordinarily high tunability are obtained for the composites with dielectric impenetrable disks at high concentrations, in which the triggering of the percolation transition is avoided. The reported results cast light on distinct nonlinear behaviour of 2D and 3D stochastic composites and can guide the design of novel composites with the controlled morphology and tailored permittivity and tunability.}},
  author       = {{Myroshnychenko, Viktor and Smirnov, Stanislav and Jose, Pious Mathews Mulavarickal and Brosseau, Christian and Förstner, Jens}},
  issn         = {{1359-6454}},
  journal      = {{Acta Materialia}},
  pages        = {{116432}},
  title        = {{{Nonlinear dielectric properties of random paraelectric-dielectric composites}}},
  doi          = {{10.1016/j.actamat.2020.10.051}},
  volume       = {{203}},
  year         = {{2020}},
}

@article{17803,
  abstract     = {{We numerically simulate multiple light scattering in discrete disordered media represented by large clusters of irregular non-absorbing particles. The packing density of clusters is 0.5. With such conditions diffuse scattering is significantly reduced and light transport follows propagation channels that are determined by the particle size and topology of the medium. This kind of localization produces coherent backscattering intensity surge and enhanced negative polarization branch if compared to lower density samples.}},
  author       = {{Grynko, Yevgen and Shkuratov, Yuriy and Förstner, Jens}},
  issn         = {{0022-4073}},
  journal      = {{Journal of Quantitative Spectroscopy and Radiative Transfer}},
  keywords     = {{tet_topic_scattering}},
  pages        = {{107234}},
  title        = {{{Light backscattering from large clusters of densely packed irregular particles}}},
  doi          = {{10.1016/j.jqsrt.2020.107234}},
  volume       = {{255}},
  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}},
}

@inproceedings{21719,
  abstract     = {{We fabricate silicon tapers to increase the mode overlap of superconducting detectors on Ti:LiNbO3 waveguides. Mode images show a reduction in mode size from 6 µm to 2 µm FWHM, agreeing with beam propagation simulations.}},
  author       = {{Protte, Maximilian and Ebers, Lena and Hammer, Manfred and Höpker, Jan Philipp and Albert, Maximilian and Quiring, Viktor and Meier, Cedrik and Förstner, Jens and Silberhorn, Christine and Bartley, Tim}},
  booktitle    = {{OSA Quantum 2.0 Conference}},
  isbn         = {{9781943580811}},
  keywords     = {{tet_topic_waveguide}},
  title        = {{{Towards Semiconductor-Superconductor-Crystal Hybrid Integration for Quantum Photonics}}},
  doi          = {{10.1364/quantum.2020.qth7a.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}},
}

@inproceedings{39966,
  author       = {{Förstner, Jens and Widhalm, A. and Mukherjee, A. and Krehs, S. and Jonas, B. and Spychala, K. and Förstner, Jens and Thiede, Andreas and Reuter, Dirk and Zrenner, Artur}},
  booktitle    = {{11th International Conference on Quantum Dots}},
  title        = {{{Ultrafast electric control of a single QD exciton}}},
  year         = {{2020}},
}

@article{8872,
  abstract     = {{We consider light scattering from a new type of model particle whose shape is represented in the form of a generalized ellipsoid having N foci, where N is greater than two. Such particles can be convex as well as concave. We use the geometrical optics approximation to study the light scattering from 3-foci particles. Non-zero elements of the scattering matrix are calculated for ensembles of randomly oriented independent transparent particles, m = n + i0. Several internal reflection orders are considered separately. It was found that the transmission-transmission (TT) and transmission-reflectance-transmission (TRT) components dominate in the formation of intensity of scattered light at large and small phase angles, respectively. We found a significant role of the total internal reflections of the TRT in the middle portion of the phase angle range. The main factors in the formation of positive linear polarization are the R and TRT component. The TT component is responsible for the formation of negative polarization branch at large phase angles.}},
  author       = {{Stankevich, Dmitriy and Hradyska, Larissa and Shkuratov, Yuriy and Grynko, Yevgen and Videen, Gorden and Förstner, Jens}},
  issn         = {{0022-4073}},
  journal      = {{Journal of Quantitative Spectroscopy and Radiative Transfer}},
  keywords     = {{tet_topic_scattering}},
  pages        = {{49}},
  title        = {{{Light scattering by 3-Foci convex and concave particles in the geometrical optics approximation}}},
  doi          = {{10.1016/j.jqsrt.2019.04.016}},
  volume       = {{231}},
  year         = {{2019}},
}

@article{12908,
  author       = {{Hammer, Manfred and Ebers, Lena and Förstner, Jens}},
  issn         = {{0740-3224}},
  journal      = {{Journal of the Optical Society of America B}},
  keywords     = {{tet_topic_waveguides}},
  pages        = {{2395}},
  title        = {{{Oblique quasi-lossless excitation of a thin silicon slab waveguide: a guided-wave variant of an anti-reflection coating}}},
  doi          = {{10.1364/josab.36.002395}},
  volume       = {{36}},
  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{8634,
  abstract     = {{A rectangular dielectric strip at some distance above an optical slab waveguide is
being considered, for evanescent excitation of the strip through the semi-guided waves supported
by the slab, at specific oblique angles. The 2.5-D configuration shows resonant transmission
properties with respect to variations of the angle of incidence, or of the excitation frequency,
respectively. The strength of the interaction can be controlled by the gap between strip and slab.
For increasing distance, our simulations predict resonant states with unit extremal reflectance
of an angular or spectral width that tends to zero, i.e. resonances with a Q-factor that tends
to infinity, while the resonance position approaches the level of the guided mode of the strip.
This exceptionally simple system realizes what might be termed a “bound state coupled to the
continuum”.}},
  author       = {{Hammer, Manfred and Ebers, Lena and Förstner, Jens}},
  journal      = {{Optics Express}},
  keywords     = {{tet_topic_waveguides}},
  number       = {{7}},
  pages        = {{8}},
  title        = {{{Oblique evanescent excitation of a dielectric strip: A model resonator with an open optical cavity of unlimited Q}}},
  doi          = {{10.1364/OE.27.009313}},
  volume       = {{27}},
  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}},
}

@inproceedings{3588,
  abstract     = {{In scientific computing, unstructured meshes are a crucial foundation for the simulation of real-world physical phenomena. Compared to regular grids, they allow resembling the computational domain with a much higher accuracy, which in turn leads to more efficient computations.<br />There exists a wealth of supporting libraries and frameworks that aid programmers with the implementation of applications working on such grids, each built on top of existing parallelization technologies. However, many approaches require the programmer to introduce a different programming paradigm into their application or provide different variants of the code. SYCL is a new programming standard providing a remedy to this dilemma by building on standard C ++17 with its so-called single-source approach: Programmers write standard C ++ code and expose parallelism using C++17 keywords. The application is<br />then transformed into a concrete implementation by the SYCL implementation. By encapsulating the OpenCL ecosystem, different SYCL implementations enable not only the programming of CPUs but also of heterogeneous platforms such as GPUs or other devices. For the first time, this paper showcases a SYCL-<br />based solver for the nodal Discontinuous Galerkin method for Maxwell’s equations on unstructured meshes. We compare our solution to a previous C-based implementation with respect to programmability and performance on heterogeneous platforms.<br}},
  author       = {{Afzal, Ayesha and Schmitt, Christian and Alhaddad, Samer and Grynko, Yevgen and Teich, Jürgen and Förstner, Jens and Hannig, Frank}},
  booktitle    = {{Proceedings of the 29th Annual IEEE International Conference on Application-specific Systems, Architectures and Processors (ASAP)}},
  isbn         = {{978-1-5386-7479-6}},
  keywords     = {{tet_topic_hpc}},
  pages        = {{49--56}},
  title        = {{{Solving Maxwell's Equations with Modern C++ and SYCL: A Case Study}}},
  doi          = {{10.1109/ASAP.2018.8445127}},
  year         = {{2018}},
}

@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}},
}