@article{3890, abstract = {{The incidenceofthin-film-guided, in-planeunguidedwavesatobliqueanglesonstraightdiscontinuities of dielectricslabwaveguides,anearlyproblemofintegratedoptics,isbeingre-considered.The3-D frequencydomainMaxwellequationsreducetoaparametrizedinhomogeneousvectorialproblemona 2-D computationaldomain,withtransparent-influx boundaryconditions.Weproposearigorousvec- torial solverbasedonsimultaneousexpansionsintopolarizedlocalslabeigenmodesalongthetwo orthogonal crosssectioncoordinates(quadridirectionaleigenmodepropagationQUEP).Thequasi-ana- lytical schemeisapplicabletoconfigurations with — in principle — arbitrary crosssectiongeometries. Examples forahigh-contrastfacetofanasymmetricslabwaveguide,forthelateralexcitationofa channel waveguide,andforastepdiscontinuitybetweenslabwaveguidesofdifferentthicknessesare discussed.}}, author = {{Hammer, Manfred}}, issn = {{0030-4018}}, journal = {{Optics Communications}}, keywords = {{tet_topic_waveguide, tet_topic_numerics}}, pages = {{447--456}}, publisher = {{Elsevier BV}}, title = {{{Oblique incidence of semi-guided waves on rectangular slab waveguide discontinuities: A vectorial QUEP solver}}}, doi = {{10.1016/j.optcom.2014.09.087}}, volume = {{338}}, year = {{2014}}, } @article{3937, abstract = {{The relevance of our definition for sensitivity in refractometric sensing, being the relative change in the transmittance of a certain output channel of an optical device over the change in the refractive index of the probed material, is discussed. It is compared to one based on spectral shift per refractive index unit change. Further, there is discussion on how group delay and sensitivity are interrelated and can be converted into each other and which physical quantities are relevant for high sensitivity. As a by-product of the theory presented, a general expression relating group delay and the ratio of the time-averaged optical energy and the input power is presented.}}, author = {{Hoekstra, Hugo J. W. M. and Hammer, Manfred}}, issn = {{0740-3224}}, journal = {{Journal of the Optical Society of America B}}, keywords = {{tet_topic_waveguide}}, number = {{7}}, publisher = {{The Optical Society}}, title = {{{General relation for group delay and the relevance of group delay for refractometric sensing}}}, doi = {{10.1364/josab.31.001561}}, volume = {{31}}, year = {{2014}}, } @inbook{3941, author = {{Declair, Stefan and Förstner, Jens}}, booktitle = {{Handbook of Optical Microcavities}}, editor = {{Choi, Anthony H.W.}}, keywords = {{tet_topic_phc}}, publisher = {{Pan Stanford Publishing Pte. Ltd.}}, title = {{{Simulation of Planar Photonic Resonators}}}, volume = {{Kapitel 2}}, year = {{2014}}, } @inproceedings{4315, abstract = {{We simulate numerically light scattering by random irregular particles of two classes of shape: Gaussian random field particles and agglomerated debri particles. Comparison of the angular dependencies of the scattering matrix elements for the case of non-absorbing material shows qualitative similarity of optical properties of both types despite different morphology of scatterers. Absorbing particles result in the difference in linear polarization. However, a strong similarty remains for the intensity curves.}}, author = {{Grynko, Yevgen and Zubko, Evgenij}}, location = {{Marseille (France)}}, title = {{{Light Scattering By Random Irregular Particles With Different Morphology}}}, year = {{2014}}, } @inproceedings{3939, abstract = {{Optical and infrared antennas provide a promising way to couple photons in and out of nanoscale structures. As counterpart to conventional radio antennas, they are able to increase optical felds in sub-wavelength volumes, to enhance excitation and emission of quantum emitters or to direct light, radiated by quantum emitters. The directed emission of these antennas has been mainly pursued by surface plasmon based devices, e.g. Yagi-Uda like antennas, which are rather complicated due to the coupling of several metallic particles. Also, like all metallic structures in optical or infrared regime, these devices are very sensitive to fabrication tolerances and are affected by strong losses. It has been shown recently, that such directed emission can be accomplished by dielectric materials as well. In this paper we present an optimization of nanoscopic antennas in the near infrared regime starting from a metallic Yagi-Uda structure. The optimization is done via a particle-swarm algorithm, using full time domain finite integration simulations to obtain the characteristics of the investigated structure, also taking into account substrates. Furthermore we present a dielectric antenna, which performs even better, due to the lack of losses by an appropriate choice of the dielectric material. These antennas are robust concerning fabrication tolerances and can be realized with different materials for both the antenna and the substrate, without using high index materials.}}, author = {{Hildebrandt, Andre and Reichelt, Matthias and Meier, Torsten and Förstner, Jens}}, booktitle = {{Ultrafast Phenomena and Nanophotonics XVIII}}, editor = {{Betz, Markus and Elezzabi, Abdulhakem Y. and Song, Jin-Joo and Tsen, Kong-Thon}}, keywords = {{tet_topic_opticalantenna}}, pages = {{89841G--8941G--6}}, publisher = {{SPIE}}, title = {{{Engineering plasmonic and dielectric directional nanoantennas}}}, doi = {{10.1117/12.2036588}}, volume = {{8984}}, year = {{2014}}, } @article{1779, author = {{Giefers, Heiner and Plessl, Christian and Förstner, Jens}}, issn = {{0163-5964}}, journal = {{ACM SIGARCH Computer Architecture News}}, keywords = {{funding-maxup, tet_topic_hpc}}, number = {{5}}, pages = {{65--70}}, publisher = {{ACM}}, title = {{{Accelerating Finite Difference Time Domain Simulations with Reconfigurable Dataflow Computers}}}, doi = {{10.1145/2641361.2641372}}, volume = {{41}}, year = {{2014}}, } @article{1783, author = {{Grynko, Yevgen and Shkuratov, Yuriy and Förstner, Jens}}, journal = {{Optical Letters}}, keywords = {{tet_topic_scattering}}, number = {{23}}, pages = {{5153--5156}}, title = {{{Light scattering by randomly irregular dielectric particles larger than the wavelength}}}, doi = {{10.1364/OL.38.005153}}, volume = {{38}}, year = {{2013}}, } @article{3959, abstract = {{Microresonators containing quantum dots find application in devices like single photon emitters for quantum information technology as well as low threshold laser devices. We demonstrate the fabrication of 60 nm thin zinc-blende AlN microdisks including cubic GaN quantum dots using dry chemical etching techniques. Scanning electron microscopy analysis reveals the morphology with smooth surfaces of the microdisks. Micro-photoluminescence measurements exhibit optically active quantum dots. Furthermore this is the first report of resonator modes in the emission spectrum of a cubic AlN microdisk.}}, author = {{Bürger, M. and Kemper, R.M. and Bader, C.A. and Ruth, M. and Declair, S. and Meier, Cedrik and Förstner, Jens and As, D.J.}}, issn = {{0022-0248}}, journal = {{Journal of Crystal Growth}}, keywords = {{tet_topic_qd, tet_topic_microdisk}}, pages = {{287--290}}, publisher = {{Elsevier BV}}, title = {{{Cubic GaN quantum dots embedded in zinc-blende AlN microdisks}}}, doi = {{10.1016/j.jcrysgro.2012.12.058}}, volume = {{378}}, year = {{2013}}, } @article{3963, abstract = {{Whispering gallery modes (WGMs) were observed in 60 nm thin cubic AlN microdisk resonators containing a single layer of non-polar cubic GaN quantum dots. Freestanding microdisks were patterned by means of electron beam lithography and a two step reactive ion etching process. Micro-photoluminescence spectroscopy investigations were performed for optical characterization. We analyzed the mode spacing for disk diameters ranging from 2-4 lm. Numerical investigations using three dimensional finite difference time domain calculations were in good agreement with the experimental data. Whispering gallery modes of the radial orders 1 and 2 were identified by means of simulated mode field distributions.}}, author = {{Bürger, M. and Ruth, M. and Declair, S. and Förstner, Jens and Meier, Cedrik and As, Donat Josef}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, keywords = {{tet_topic_qd, tet_topic_microdisk}}, number = {{8}}, pages = {{081105}}, publisher = {{AIP Publishing}}, title = {{{Whispering gallery modes in zinc-blende AlN microdisks containing non-polar GaN quantum dots}}}, doi = {{10.1063/1.4793653}}, volume = {{102}}, year = {{2013}}, } @inproceedings{4039, abstract = {{We perform experiments on resonant second-harmonic generation from planar gold split-ring-resonator arrays under normal incidence of light as a function of the lattice constant. Optimum nonlinear conversion occurs at intermediate lattice constants.}}, author = {{Niesler, Fabian B. and Linden, Stefan and Förstner, Jens and Grynko, Yevgen and Meier, Torsten and Wegener, Martin}}, booktitle = {{Conference on Lasers and Electro-Optics 2012}}, isbn = {{9781557529435}}, keywords = {{tet_topic_shg, tet_topic_meta}}, location = {{San Jose, California United States}}, number = {{1}}, publisher = {{OSA}}, title = {{{Collective effects in second-harmonic generation from split-ring-resonator arrays}}}, doi = {{10.1364/qels.2012.qth3e.2}}, volume = {{109}}, year = {{2013}}, } @inproceedings{3961, abstract = {{Previous experimental measurements and numerical simulations give evidence of strong electric and magnetic field interaction between split-ring resonators in dense arrays. One can expect that such interactions have an influence on the second harmonic generation. We apply the Discontinuous Galerkin Time Domain method and the hydrodynamic Maxwell-Vlasov model to simulate the linear and nonlinear optical response from SRR arrays. The simulations show that dense placement of the constituent building blocks appears not always optimal and collective effects can lead to a significant suppression of the near fields at the fundamental frequency and, consequently, to the decrease of the SHG intensity. We demonstrate also the great role of the symmetry degree of the array layout which results in the variation of the SHG efficiency in range of two orders of magnitude.}}, author = {{Grynko, Yevgen and Meier, Torsten and Linden, Stefan and Niesler, Fabian B. P. and Wegener, Martin and Förstner, Jens}}, booktitle = {{Ultrafast Phenomena and Nanophotonics XVII}}, editor = {{Betz, Markus and Elezzabi, Abdulhakem Y. and Song, Jin-Joo and Tsen, Kong-Thon}}, keywords = {{tet_topic_shg, tet_topic_meta}}, pages = {{86230L--86230L--9}}, publisher = {{SPIE}}, title = {{{Optimal second-harmonic generation in split-ring resonator arrays}}}, doi = {{10.1117/12.2003279}}, volume = {{8623}}, year = {{2013}}, } @inproceedings{3980, abstract = {{Paper Abstract High harmonic generation is investigated for a two-band model of a semiconductor nanostructure. Similar to an atomic two-level system, the semiconductor emits high harmonic radiation. We show how one can specifically enhance the emission for a given frequency by applying a non-trivially shaped laser pulse. Therefore, the semiconductor Bloch equations including the interband and additionally the intraband dynamics are solved numerically and the spectral shape of the input pulse is computed via an optimization algorithm. It is demonstrated that desired emission frequencies can be favored even though the overall input power is kept constant. We also suggest special metallic nano geometries to achieve enhanced localized optical fields. They are found by geometric optimization.}}, author = {{Reichelt, Matthias and Hildebrandt, Andre and Walther, Andrea and Förstner, Jens and Meier, Torsten}}, booktitle = {{Ultrafast Phenomena and Nanophotonics XVI}}, isbn = {{9780819489036 }}, keywords = {{tet_topic_shg}}, publisher = {{SPIE}}, title = {{{Engineering high harmonic generation in semiconductors via pulse shaping}}}, doi = {{10.1117/12.906338}}, volume = {{8260}}, year = {{2012}}, } @inproceedings{2106, abstract = {{Although the benefits of FPGAs for accelerating scientific codes are widely acknowledged, the use of FPGA accelerators in scientific computing is not widespread because reaping these benefits requires knowledge of hardware design methods and tools that is typically not available with domain scientists. A promising but hardly investigated approach is to develop tool flows that keep the common languages for scientific code (C,C++, and Fortran) and allow the developer to augment the source code with OpenMPlike directives for instructing the compiler which parts of the application shall be offloaded the FPGA accelerator. In this work we study whether the promise of effective FPGA acceleration with an OpenMP-like programming effort can actually be held. Our target system is the Convey HC-1 reconfigurable computer for which an OpenMP-like programming environment exists. As case study we use an application from computational nanophotonics. Our results show that a developer without previous FPGA experience could create an FPGA-accelerated application that is competitive to an optimized OpenMP-parallelized CPU version running on a two socket quad-core server. Finally, we discuss our experiences with this tool flow and the Convey HC-1 from a productivity and economic point of view.}}, author = {{Meyer, Björn and Schumacher, Jörn and Plessl, Christian and Förstner, Jens}}, booktitle = {{Proc. Int. Conf. on Field Programmable Logic and Applications (FPL)}}, keywords = {{funding-upb-forschungspreis, funding-maxup, tet_topic_hpc}}, pages = {{189--196}}, publisher = {{IEEE}}, title = {{{Convey Vector Personalities – FPGA Acceleration with an OpenMP-like Effort?}}}, doi = {{10.1109/FPL.2012.6339370}}, year = {{2012}}, } @article{3974, abstract = {{We study the quantum properties and statistics of photons emitted by a quantum-dot biexciton inside a cavity. In the biexciton-exciton cascade, fine-structure splitting between exciton levels degrades polarization-entanglement for the emitted pair of photons. However, here we show that the polarization-entanglement can be preserved in such a system through simultaneous emission of two degenerate photons into cavity modes tuned to half the biexciton energy. Based on detailed theoretical calculations for realistic quantum-dot and cavity parameters, we quantify the degree of achievable entanglement.}}, author = {{Schumacher, Stefan and Förstner, Jens and Zrenner, Artur and Florian, Matthias and Gies, Christopher and Gartner, Paul and Jahnke, Frank}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{tet_topic_qd}}, number = {{5}}, pages = {{5335--5342}}, publisher = {{OSA}}, title = {{{Cavity-assisted emission of polarization-entangled photons from biexcitons in quantum dots with fine-structure splitting}}}, doi = {{10.1364/oe.20.005335}}, volume = {{20}}, year = {{2012}}, } @inproceedings{3965, abstract = {{We design the geometrical shape of plasmonic nanostructures to achieve field patterns with desired properties. For this, we combine Maxwell simulations and automatic optimization techniques. By allowing variations of the geometrical shape, which can be based on either boxes or arbitrary polygons, we maximize the desired objective.}}, author = {{Hildebrandt, Andre and Reichelt, Matthias and Meier, Torsten and Förstner, Jens}}, keywords = {{tet_topic_optical antenna, tet_topic_plasmonics}}, location = {{Bad Honnef}}, number = {{59}}, publisher = {{AIP AIP Conference Proceedings 1475}}, title = {{{Optimization of the intensity enhancement in plasmonic nanoantennas}}}, doi = {{10.1063/1.4750095}}, year = {{2012}}, } @article{3972, abstract = {{Using a finite-difference time-domain method, we theoretically investigate the optical spectra of crossing perpendicular photonic crystal waveguides with quantum dots embedded in the central rod. The waveguides are designed so that the light mainly propagates along one direction and the cross talk is greatly reduced in the transverse direction. It is shown that when a quantum dot (QD) is resonant with the cavity, strong coupling can be observed via both the transmission and crosstalk spectrum. If the cavity is far off-resonant from the QD, both the cavity mode and the QD signal can be detected in the transverse direction since the laser field is greatly suppressed in this direction. This structure could have strong implications for resonant excitation and in-plane detection of QD optical spectroscopy.}}, author = {{Song, Xiaohong and Declair, Stefan and Meier, Torsten and Zrenner, Artur and Förstner, Jens}}, issn = {{1094-4087}}, journal = {{Optics Express}}, keywords = {{tet_topic_phc, tet_topic_qd}}, number = {{13}}, pages = {{14130--14136}}, publisher = {{The Optical Society}}, title = {{{Photonic crystal waveguides intersection for resonant quantum dot optical spectroscopy detection}}}, doi = {{10.1364/oe.20.014130}}, volume = {{20}}, year = {{2012}}, } @inproceedings{3967, abstract = {{We simulate the linear and nonlinear optical response from split-ring resonator (SRR) arrays to study collective effects between the constituent SRRs that determine spectral properties of the second harmonic generation (SHG). We apply the Discontinuous Galerkin Time Domain (DGTD) method and the hydrodynamic Maxwell-Vlasov model to calculate the SHG emission. Our model is able to qualitatively reproduce and explain the non-monotonic dependence of the spectral SHG transmission measured experimentally for SRR arrays with different lattice constants}}, author = {{Grynko, Yevgen and Meier, Torsten and Linden, Stefan and Niesler, Fabian B. P. and Wegener, Martin and Förstner, Jens}}, keywords = {{tet_topic_meta, tet_topic_shg}}, location = {{Bad Honnef}}, number = {{1}}, pages = {{128--130}}, publisher = {{AIP Conference Proceedings}}, title = {{{Near-field coupling and second-harmonic generation in split-ring resonator arrays}}}, doi = {{10.1063/1.4750118}}, volume = {{1475}}, year = {{2012}}, } @article{3970, abstract = {{Optical experiments on second-harmonic generation from split-ring-resonator square arrays show a nonmonotonic dependence of the conversion efficiency on the lattice constant. This finding is interpreted in terms of a competition between dilution effects and linewidth or near-field changes due to interactions among the individual elements in the array.}}, author = {{Linden, S. and Niesler, F. B. P. and Förstner, Jens and Grynko, Yevgen and Meier, Torsten and Wegener, M.}}, issn = {{0031-9007}}, journal = {{Physical Review Letters}}, keywords = {{tet_topic_shg, tet_topic_meta}}, number = {{1}}, publisher = {{American Physical Society (APS)}}, title = {{{Collective Effects in Second-Harmonic Generation from Split-Ring-Resonator Arrays}}}, doi = {{10.1103/physrevlett.109.015502}}, volume = {{109}}, year = {{2012}}, } @misc{4171, abstract = {{The method involves exciting a quantum system with photons in a polarization state. Two states of the quantum system are excited with linear horizontal and vertical polarizations that are orthogonal to each other, where the states exhibit an energetic gap smaller than energetic bandwidth of photons. The states are assigned based on the polarizations, where the quantum system is arranged in a superposition state. The quantum system is formed by a quantum bit that is formed as a two-level system.}}, author = {{Förstner, Jens and Mantei, D. and de Vasconcellos, S. Michaelis and Zrenner, Artur}}, keywords = {{tet_topic_qd}}, title = {{{Method for transmission of information about polarization state of photons to stationary system}}}, year = {{2011}}, } @inproceedings{4312, abstract = {{The intensity dependence of optically-induced injection currents in semiconductor quantum wells is investigated numerically. Oscillatory behavior of the electron charge current transients as function of intensity and time is predicted and explained.}}, author = {{Pochwala, Michal and Duc, Huynh Thanh and Förstner, Jens and Meier, Torsten}}, booktitle = {{CLEO:2011 - Laser Applications to Photonic Applications}}, isbn = {{9781557529107}}, issn = {{2160-8989 }}, keywords = {{tet_topic_qw}}, location = {{Baltimore, Maryland (USA)}}, publisher = {{Optical Society of America}}, title = {{{Intensity dependence of optically-induced injection currents in semiconductor quantum wells}}}, doi = {{10.1364/qels.2011.qmk4}}, year = {{2011}}, }