@inbook{43260,
  author       = {{Güdde, J. and Rohleder, M. and Meier, Torsten and Koch, S.W. and Höfer, U.}},
  booktitle    = {{Dynamics at Solid State Surfaces and Interfaces}},
  editor       = {{Bovensiepen, U. and Petek, H. and Wolf, M.}},
  pages        = {{579--591}},
  publisher    = {{Wiley‐VCH Verlag}},
  title        = {{{Coherently controlled electrical currents at surfaces}}},
  doi          = {{10.1002/9783527633418.ch24}},
  volume       = {{1}},
  year         = {{2010}},
}

@article{4127,
  abstract     = {{The dynamics of charge and spin injection currents excited by circularly polarized, one-color laser beams in
semiconductor quantum wells is analyzed. Our microscopic approach is based on a 14x14 k · p band-structure
theory in combination with multisubband semiconductor Bloch equations which allows a detailed analysis of
the photogenerated carrier distributions and coherences in k space. Charge and spin injection currents are
numerically calculated for [110]- and [001]-grown GaAs quantum wells including dc population contributions
and ac contributions that arise from intersubband coherences. The dependencies of the injection currents on the
excitation conditions, in particular, the photon energy are computed and discussed.}},
  author       = {{Duc, Huynh Thanh and Förstner, Jens and Meier, Torsten}},
  issn         = {{1098-0121}},
  journal      = {{Physical Review B}},
  keywords     = {{tet_topic_qw}},
  number       = {{11}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Microscopic analysis of charge and spin photocurrents injected by circularly polarized one-color laser pulses in GaAs quantum wells}}},
  doi          = {{10.1103/physrevb.82.115316}},
  volume       = {{82}},
  year         = {{2010}},
}

@inproceedings{43261,
  abstract     = {{We report the development of an experimental technique to measure the dynamics of electrical currents on the femtosecond timescale. The technique combines methods of coherent control with time- and angle-resolved photoelectron spectroscopy. Direct snapshots of the momentum distribution of the excited electrons as function of time are then determined by photoelectron spectroscopy. In this way we gain information on the generation and decay of ultrashort current pulses in unprecedented detail. In particular, this technique allows the observation of elastic electron scattering in terms of an incoherent population dynamics in momentum space. We have applied this optical current generation and detection scheme to electrons in so-called image-potential states which represent a prototype of two-dimensional electronic surface states. Electrons in these states are bound perpendicular to the metal surface by the Coulombic image potential whereas they can move almost freely parallel to the surface. For the (n=1) image-potential state of Cu(100) we find a decay time of 10 fs due to electron scattering with steps and surface defects.}},
  author       = {{Güdde, J. and Rohleder, M. and Meier, Torsten and Koch, S.W. and Höfer, U.}},
  booktitle    = {{Ultrafast Phenomena in Semiconductors and Nanostructure Materials XIV}},
  editor       = {{Song, Jin-Joo and Tsen, Kong-Thon and Betz, Markus and Y. Elezzabi, Abdulhakem}},
  publisher    = {{SPIE}},
  title        = {{{Ultrafast coherent control of electric currents at metal surfaces}}},
  doi          = {{10.1117/12.839672}},
  volume       = {{7600}},
  year         = {{2010}},
}

@inproceedings{4176,
  abstract     = {{A microscopic theory that describes injection currents in GaAs quantum wells is presented. 14 × 14 band k.p theory is used to compute the band structure including anisotropy and spin-orbit interaction. Transient injection currents are obtained via numerical solutions of the semiconductor Bloch equations. Depending on the growth direction of the considered quantum well system and the propagation and polarization directions of the incident light beam, it is possible to generate charge and/or spin photocurrents on ultrashort time scales. The dependence of the photocurrents on the excitation conditions is computed and discussed.}},
  author       = {{Duc, Huynh Thanh and Förstner, Jens and Meier, Torsten}},
  booktitle    = {{Ultrafast Phenomena in Semiconductors and Nanostructure Materials XIV}},
  editor       = {{Song, Jin-Joo and Tsen, Kong-Thon and Betz, Markus and Elezzabi, Abdulhakem Y.}},
  keywords     = {{tet_topic_qw}},
  pages        = {{76000S--76000S--9}},
  publisher    = {{SPIE}},
  title        = {{{Microscopic theoretical analysis of optically generated injection currents in semiconductor quantum wells}}},
  doi          = {{10.1117/12.840388}},
  volume       = {{7600}},
  year         = {{2010}},
}

@article{44063,
  abstract     = {{We present an analysis of the coupling between photonic crystal cavities in different geometries. Inline‐, side‐ and angle‐coupled L3‐geometries are investigated numerically in three dimensions. Asymmetric mode splitting of the fundamental mode for the L3‐cavity is shown for all geometrical setups evidencing for strong cavity‐cavity interactions. The coupling efficiency for the fundamental mode is shown to be best for a 30° angle between the cavity‐centers due to the direction of in‐plane leackage out of the cavites.}},
  author       = {{Meier, Torsten and Declair, S. and Förstner, J.}},
  journal      = {{AIP Conference Proceedings}},
  number       = {{46 }},
  publisher    = {{American Institute of Physics}},
  title        = {{{Numerical Analysis of Coupled Photonic Crystal Cavities}}},
  doi          = {{10.1063/1.3506125}},
  volume       = {{1291}},
  year         = {{2010}},
}

@article{24980,
  abstract     = {{We discuss transport and localization properties on the insulating side of the disorder dominated superconductor-insulator transition, described in terms of the dirty boson model. Analyzing the spectral properties of the interacting bosons in the absence of phonons, we argue that the Bose glass phase admits three distinct regimes. For strongest disorder the boson system is a fully localized, perfect insulator at any temperature. At smaller disorder, only the low temperature phase exhibits perfect insulation while delocalization takes place above a finite temperature. We argue that a third phase must intervene between these perfect insulators and the superconductor. This conducting Bose glass phase is characterized by a mobility edge in the many body spectrum, located at finite energy above the ground state. In this insulating regime purely electronically activated transport occurs, with a conductivity following an Arrhenius law at asymptotically low temperatures, while a tendency to superactivation is predicted at higher T. These predictions are in good agreement with recent transport experiments in highly disordered films of superconducting materials.}},
  author       = {{Gögh, N. and Thomas, P. and Kuznetsova, I. and Meier, Torsten and Varga, I.}},
  issn         = {{0003-3804}},
  journal      = {{Annalen der Physik}},
  number       = {{12}},
  pages        = {{905--909}},
  title        = {{{Localization of excitons in weakly disordered semiconductor structures: A model study}}},
  doi          = {{10.1002/andp.20095211219}},
  volume       = {{18}},
  year         = {{2010}},
}

@article{23480,
  abstract     = {{We discuss transport and localization properties on the insulating side of the disorder dominated superconductor-insulator transition, described in terms of the dirty boson model. Analyzing the spectral properties of the interacting bosons in the absence of phonons, we argue that the Bose glass phase admits three distinct regimes. For strongest disorder the boson system is a fully localized, perfect insulator at any temperature. At smaller disorder, only the low temperature phase exhibits perfect insulation while delocalization takes place above a finite temperature. We argue that a third phase must intervene between these perfect insulators and the superconductor. This conducting Bose glass phase is characterized by a mobility edge in the many body spectrum, located at finite energy above the ground state. In this insulating regime purely electronically activated transport occurs, with a conductivity following an Arrhenius law at asymptotically low temperatures, while a tendency to superactivation is predicted at higher T. These predictions are in good agreement with recent transport experiments in highly disordered films of superconducting materials.}},
  author       = {{Gögh, N. and Thomas, P. and Kuznetsova, I. and Meier, Torsten and Varga, I.}},
  issn         = {{0003-3804}},
  journal      = {{Annalen der Physik}},
  number       = {{12}},
  pages        = {{905--909}},
  title        = {{{Localization of excitons in weakly disordered semiconductor structures: A model study}}},
  doi          = {{10.1002/andp.200910382}},
  year         = {{2010}},
}

@inproceedings{44064,
  abstract     = {{We compute photocurrents generated by femtosecond single-color laser pulses in non-centrosymmetric semiconductor quantum wells by combining a 14 x 14 k.p band structure theory with multi-band semiconductor Bloch equations. The transient photocurrents are investigated experimentally by measuring the associated Terahertz emission. The dependencies of the photocurrent and the Terahertz emission on the excitation conditions are discussed for (110)-oriented GaAs quantum wells. The comparison between theory and experiment shows a good agreement.}},
  author       = {{Meier, Torsten and Duc, Huynh Thanh and Foerstner, Jens and Priyadarshi, S. and Racu, Ana Maria and Pierz, Klaus and Siegner, Uwe and Bieler, Mark}},
  booktitle    = {{DPG Spring meeting 2010 }},
  issn         = {{0420-0195}},
  location     = {{Regensburg, Germany}},
  number       = {{3}},
  title        = {{{Experimental and theoretical investigations of photocurrents in non-centrosymmetric semiconductor quantum wells}}},
  volume       = {{45}},
  year         = {{2010}},
}

@inproceedings{44067,
  abstract     = {{Semiconductor nanostructures always contain a certain degree of disorder due to interface roughness and/or alloy disorder. The disorder has significant influence on the optical properties, e.g., excitonic absorption spectra. An adaptive wavelet approach for the solution of the excitonic Schroedinger equation, i.e., the semiconductor Bloch equation for the interband coherence linear in the external field, has been developed and applied to compute absorption spectra and/or wave functions. Results obtained for a thin GaAs semiconductor quantum wire considering a number of different model disorder potentials are presented and discussed.}},
  author       = {{Meier, Torsten and Mollet, Christian and Kunoth, Angela}},
  booktitle    = {{DPG Spring meeting 2010}},
  issn         = {{ 0420-0195}},
  location     = {{Regensburg, Germany}},
  number       = {{3}},
  title        = {{{A numerical adaptive wavelet approach to excitonic absorption spectra of disordered semiconductor nanostructures}}},
  volume       = {{45}},
  year         = {{2010}},
}

@inproceedings{44065,
  abstract     = {{The behavior of waveguide plasmon polaritons is studied employing ultrafast coherent control like schemes for a gold lattice coupled to a photonic waveguide for the structure. Different models to describe the third-harmonic generation are presented and the resulting equations are solved numerically. The calculations are compared to recent experimental data and show good agreement for the most prominent features in the time-integrated third order intensity.}},
  author       = {{Meier, Torsten and Podzimski, Reinold and Reichelt, Matthias and Utikal, Tobias and Giessen, Harald}},
  booktitle    = {{DPG Spring meeting 2010}},
  issn         = {{0420-0195}},
  location     = {{Regensburg, Germany}},
  number       = {{3}},
  title        = {{{Controlling the third-harmonic generation in a metallic photonic crystal coupled to a waveguide}}},
  volume       = {{45}},
  year         = {{2010}},
}

@inproceedings{44066,
  abstract     = {{We present a joint theoretical study of the optical properties of GaAs and AlAs bulk and heterostructures. Thereby, we compare the theoretical description of optical excitation on several levels of theory. Results obtained from kp theory are discussed along with data from ab initio calculations within the frameworks of independent-particle (DFT), independent quasiparticle (GW), or Coulomb-correlated quasiparticle (BSE) approximation.}},
  author       = {{Meier, Torsten and Landmann, Marc and Pochwala, Michal and Foerstner, Jens and Rauls, Eva and Schmidt, Wolf Gero}},
  booktitle    = {{DPG Spring meeting 2010}},
  issn         = {{0420-0195}},
  location     = {{Regensburg, Germany}},
  number       = {{3}},
  title        = {{{Theoretical description of optical properties in III-V semiconductor nanostructures}}},
  volume       = {{45}},
  year         = {{2010}},
}

@article{4177,
  abstract     = {{Excitonic spectra of weakly disordered semiconductor heterostructures are simulated on the basis of a
one-dimensional tight-binding model. The influence of the length scale of weak disorder in quantum wells on
the redshift of the excitonic peak and its linewidth is studied. By calculating two-dimensional Fouriertransform
spectra we are able to determine the contribution of disorder to inhomogeneous and also to homogeneous
broadenings separately. This disorder-induced dephasing is related to a Fano-type coupling and leads
to contributions to the homogeneous linewidth that depends on energy within the inhomogeneously broadened
line. The model includes heavy- and light-hole excitons and yields smaller inhomogeneous broadening for the
light-hole exciton if compared to the heavy-hole exciton, which agrees qualitatively with the experiment.}},
  author       = {{Kuznetsova, I. and Gőgh, N. and Förstner, Jens and Meier, Torsten and Cundiff, S. T. and Varga, I. and Thomas, P.}},
  issn         = {{1098-0121}},
  journal      = {{Physical Review B}},
  keywords     = {{tet_topic_qw}},
  number       = {{7}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Modeling excitonic line shapes in weakly disordered semiconductor nanostructures}}},
  doi          = {{10.1103/physrevb.81.075307}},
  volume       = {{81}},
  year         = {{2010}},
}

@article{4125,
  abstract     = {{We numerically investigate the behavior of Whispering Gallery Modes (WGMs) in circularly shaped resonators like microdisks, with diameters in the range of optical vacuum wavelengths. The microdisk is embedded in an uniaxial anisotropic dielectric environment. By changing the optical anisotropy, one obtains spectral tunability of the optical modes. The degree of tunability strongly depends on the radial (azimuthal) mode order M (N). As the modes approach each other spectrally, anticrossing is observed, leading to a rearrangement of the optical states.}},
  author       = {{Declair, S. and Meier, Cedrik and Meier, Torsten and Förstner, Jens}},
  issn         = {{1569-4410}},
  journal      = {{Photonics and Nanostructures - Fundamentals and Applications}},
  keywords     = {{tet_topic_microdisk}},
  number       = {{4}},
  pages        = {{273--277}},
  publisher    = {{Elsevier BV}},
  title        = {{{Anticrossing of Whispering Gallery Modes in microdisk resonators embedded in an anisotropic environment}}},
  doi          = {{10.1016/j.photonics.2010.03.002}},
  volume       = {{8}},
  year         = {{2010}},
}

@article{4547,
  abstract     = {{The coherent state manipulation of single quantum systems is a fundamental requirement for the implementation of quantum information processors. Exciton qubits are of particular interest for coherent optoelectronic applications, in particular due to their excellent coupling to photons. Until now, coherent manipulations of exciton qubits in semiconductor quantum dots have been performed predominantly by pulsed laser fields. Coherent control of the population of excitonic states with a single laser pulse, observed by Rabi oscillations, has been demonstrated by several groups using different techniques1,2,3. By using two laser pulses, more general state control can be achieved4, and coupling of two excitons has been reported5,6. Here, we present a conceptually new approach for implementing the coherent control of an exciton two-level system (qubit) by means of a time-dependent electric interaction. The new scheme makes use of an optical clock signal and a synchronous electric gate signal, which controls the coherent manipulation.}},
  author       = {{Michaelis de Vasconcellos, S. and Gordon, S. and Bichler, M. and Meier, Torsten and Zrenner, Artur}},
  issn         = {{1749-4885}},
  journal      = {{Nature Photonics}},
  number       = {{8}},
  pages        = {{545--548}},
  publisher    = {{Springer Nature}},
  title        = {{{Coherent control of a single exciton qubit by optoelectronic manipulation}}},
  doi          = {{10.1038/nphoton.2010.124}},
  volume       = {{4}},
  year         = {{2010}},
}

@article{4123,
  abstract     = {{GaAs-based semiconductor microdisks with high quality whispering gallery modes (Q44000) have been fabricated.A layer of self-organized InAs quantumdots (QDs) served as a light source to feed the optical modes at room temperature. In order to achieve frequency tuning of the optical modes, the microdisk devices have been immersed in 4 – cyano – 4´-pentylbiphenyl (5CB), a liquid crystal(LC) with a nematic phase below the clearing temperature of  TC≈34°C .We have studied the device performance in the temperature rangeof T=20-50°C, in order to investigate the influence of the nematic–isotropic phase transition on the optical modes. Moreover,we havea pplied an AC electric field to the device,which leads in the nematic phase to a reorientation of the anisotropic dielectric tensor of the liquid crystal.This electrical anisotropy can be used to achieve electrical tunability of the optical modes.Using the finite-difference time domain (FDTD) technique with an anisotropic material model, we are able to describe the influence of the liquid crystal qualitatively.}},
  author       = {{Piegdon, Karoline A. and Offer, Matthias and Lorke, Axel and Urbanski, Martin and Hoischen, Andreas and Kitzerow, Heinz-Siegfried and Declair, Stefan and Förstner, Jens and Meier, Torsten and Reuter, Dirk and Wieck, Andreas D. and Meier, Cedrik}},
  issn         = {{1386-9477}},
  journal      = {{Physica E: Low-dimensional Systems and Nanostructures}},
  keywords     = {{tet_topic_qd, tet_topic_microdisk}},
  number       = {{10}},
  pages        = {{2552--2555}},
  publisher    = {{Elsevier BV}},
  title        = {{{Self-assembled quantum dots in a liquid-crystal-tunable microdisk resonator}}},
  doi          = {{10.1016/j.physe.2009.12.051}},
  volume       = {{42}},
  year         = {{2010}},
}

@article{4169,
  abstract     = {{It is demonstrated that valence-band mixing in GaAs quantum wells tremendously modifies electronic
transport. A coherent control scheme in which ultrafast currents are optically injected into undoped GaAs
quantum wells upon excitation with femtosecond laser pulses is employed. An oscillatory dependence of
the injection current amplitude and direction on the excitation photon energy is observed. A microscopic
theoretical analysis shows that this current reversal is caused by the coupling of the light- and heavy-hole
bands and that the hole currents dominate the overall current response. These surprising consequences of
band mixing illuminate fundamental physics as they are unique for experiments which are able to monitor
electronic transport resulting from carriers with relatively large momenta.}},
  author       = {{Priyadarshi, S. and Racu, A. M. and Pierz, K. and Siegner, U. and Bieler, M. and Duc, H. T. and Förstner, Jens and Meier, Torsten}},
  issn         = {{0031-9007}},
  journal      = {{Physical Review Letters}},
  keywords     = {{tet_topic_qw}},
  number       = {{21}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Reversal of Coherently Controlled Ultrafast Photocurrents by Band Mixing in Undoped GaAs Quantum Wells}}},
  doi          = {{10.1103/physrevlett.104.217401}},
  volume       = {{104}},
  year         = {{2010}},
}

@inproceedings{4167,
  abstract     = {{The electromagnetic field in the vicinity of sharp edges needs a special treatment in numeric calculation whenever accurate, fast converging results are necessary. One of the fundamental works concerning field singularities has been proposed in 1972 [1] and states that the electromagnetic energy density must be integrable over any finite
domain, even if this domain contains singularities. It is shown, that the magnetic field H(, ϕ) and electric field E(, ϕ) are proportional to ∝ (t−1) for  → 0. The variable  is the distance to the edge and t has to fulfill the integrability condition and thus is restricted to 0 < t < 1. This result is often used to reduce the error corresponding to the singularity without increasing the numerical effort [2 - 5]. For this purpose, a correction factor K is estimated by inserting the proportionality into the wave equation. It is shown, that this method improves the accuracy of the result significantly, however the order of convergence is often not studied. In [4] a method to modify the material parameters in order to use analytic results to improve the numeric calculation is presented. In this contribution we will - inspired by the scheme given in [4] - develop a new method to estimate a correction factor for perfect conducting materials (PEC) and demonstrate the improvement of the results compared to the standard edge correction. Therefore analytic results (comparable to [1]) are consequently merged with the scheme in [4]. The main goal of this work is the calculation of the second harmonic generation (SHG) in the wave response of so-called metamaterials [6]. Frequently these structures
contain sharp metallic edges with field singularities at the interfaces which have a strong impact on the SHG signals. Thus, an accurate simulation of singularities is highly important. However, the following approach can also be applied to many other setups, and one of them is shown in the example below.}},
  author       = {{Classen, C and Förstner, Jens and Meier, Torsten and Schuhmann, R}},
  booktitle    = {{2010 IEEE Antennas and Propagation Society International Symposium}},
  isbn         = {{9781424449675}},
  keywords     = {{tet_topic_numerics}},
  location     = {{Toronto, ON, Canada}},
  publisher    = {{IEEE}},
  title        = {{{Enhanced FDTD edge correction for nonlinear effects calculation}}},
  doi          = {{10.1109/aps.2010.5562017}},
  year         = {{2010}},
}

@article{4172,
  abstract     = {{Microdisks made from GaAs with embedded InAs quantum dots are immersed in the liquid crystal 4-cyano-4’-pentylbiphenyl (5CB). The quantum dots serve as emitters feeding the optical modes of the photonic cavity. By changing temperature, the liquid crystal undergoes a phase transition from the isotropic to the nematic state, which can be used
as an effective tuning mechanism of the photonic modes of the cavity. In the nematic state, the uniaxial electrical anisotropy of the liquid crystal molecules can be exploited for orienting the material in an electric field,
thus externally controlling the birefringence of the material. Using this effect, an electric field induced tuning of the modes is achieved. Numerical simulations using the finite-differences time-domain (FDTD) technique
employing an anisotropic dielectric medium allow to understand the alignment of the liquid crystal molecules on the surface of the microdisk resonator.}},
  author       = {{Piegdon, Karoline A. and Declair, Stefan and Förstner, Jens and Meier, Torsten and Matthias, Heiner and Urbanski, Martin and Kitzerow, Heinz-Siegfried and Reuter, Dirk and Wieck, Andreas D. and Lorke, Axel and Meier, Cedrik}},
  issn         = {{1094-4087}},
  journal      = {{Optics Express}},
  keywords     = {{tet_topic_qd, tet_topic_microdisk}},
  number       = {{8}},
  publisher    = {{The Optical Society}},
  title        = {{{Tuning quantum-dot based photonic devices with liquid crystals}}},
  doi          = {{10.1364/oe.18.007946}},
  volume       = {{18}},
  year         = {{2010}},
}

@inproceedings{44108,
  author       = {{Meier, Torsten and Zhang, Tianhao and Kuznetsova, Irina and Yang, Lijun and Bristow, Alan D and Dai, Xingcan and Li, Xiaoqin and Thomas, P. and Mukamel, S. and Mirin, Richard P. and Cundiff, S.T.}},
  booktitle    = {{Ultrafast Phenomena XVI: Proceedings of the 16th International Conference, Palazzo dei Congressi Stresa, Italy, June 9--13, 2008}},
  location     = {{Palazzo dei Congressi Stresa, Italy}},
  pages        = {{247--249}},
  publisher    = {{Springer Berlin Heidelberg}},
  title        = {{{Ultrafast Coherent Interactions in Quantum Wells Studied by Two-Dimensional Fourier Transform Spectroscopy}}},
  year         = {{2009}},
}

@article{44107,
  abstract     = {{We demonstrate a technique for the generation and detection of electron currents at surfaces on a femtosecond time scale with a contact-free experimental setup based on a combination of coherent control and photoemission spectroscopy. We have applied this technique for electrons excited into image-potential states on a Cu(100) surface that form a free-electron-like band in the direction parallel to the surface. The photogeneration of currents is described by optical Bloch equations for a multiband model. By incorporating field-induced interband and intersubband transitions together with intraband accelerations into the model, the observed phase dependence of the population and of the current can be reproduced.}},
  author       = {{Meier, Torsten and Güdde, Jens and Rohleder, M. and Koch, S.W. and Höfer, Ulrich}},
  journal      = {{physica status solidi c}},
  number       = {{2}},
  pages        = {{461--465}},
  publisher    = {{WILEY‐VCH Verlag}},
  title        = {{{Generation and time‐resolved detection of coherently controlled electric currents at surfaces}}},
  doi          = {{10.1002/pssc.200880350}},
  volume       = {{6}},
  year         = {{2009}},
}