@article{43586, abstract = {{We report results on selection rules and polarization conditions for quantum beating between light hole and heavy hole excitons in GaAs quantum wells. The measurements were conducted using time-integrated degenerate-four-wave-mixing in a three-pulse configuration. By choosing particular polarization configurations of the ultrashort optical pulses exciting heavy and light hole excitons simultaneously, degenerate four-wave-mixing signals show either quantum beating or no modulation at all. The experiments are analyzed using a model that takes into account exciton/exciton interaction.}}, author = {{Meier, Torsten and Smith, G.O. and Mayer, E.J. and Heuckeroth, V. and Kuhl, J. and Bott, K. and Schulze, A. and Bennhardt, D. and Koch, S.W. and Thomas, P. and Hey, R. and Ploog, K.}}, journal = {{Solid state communications}}, number = {{5}}, pages = {{373--377}}, publisher = {{Pergamon}}, title = {{{Polarization selection rules for quantum beating between light-and heavy-hole excitons in GaAs quantum wells}}}, doi = {{10.1016/0038-1098(95)00052-6}}, volume = {{94}}, year = {{1995}}, } @article{43590, abstract = {{The effective dimensionality of excitons can be drastically changed by applying an alternating electric field. On the basis of a full three-dimensional description of both coherent and incoherent phenomena in anisotropic structures it is found that appropriate applied oscillating fields change the exciton wave function from anisotropic three dimensional to basically two dimensional. This effective-dimension change is caused by dynamic localization which leads to an increase of the exciton binding energy and of the corresponding oscillator strength.}}, author = {{Meier, Torsten and Rossi, F. and Thomas, P. and Koch, S.W.}}, journal = {{Physical review letters}}, number = {{13}}, pages = {{2558--2561}}, publisher = {{American Physical Society}}, title = {{{Dynamic Localization in Anisotropic Coulomb Systems: Field induced Crossover of the Exciton Dimension}}}, doi = {{10.1103/PhysRevLett.75.2558}}, volume = {{75}}, year = {{1995}}, } @article{43591, abstract = {{Quasiequilibrium nonlinear optical absorption spectra are computed for semiconductor superlattices. The theory generalizes the semiconductor Bloch equations to describe anisotropic structures. The equation for the interband polarization is solved numerically and the carrier‐density dependent optical nonlinearities are computed. Starting from excitonic absorption, with increasing density exciton saturation and the development of gain is observed. The dependence of the gain spectra on structural parameters of the superlattice is discussed.}}, author = {{Meier, Torsten and Je, K.-C and Rossi, F. and Koch, S.W.}}, journal = {{Applied physics letters}}, number = {{20}}, pages = {{2978--2980}}, publisher = {{American Institute of Physics}}, title = {{{Theory of quasi-equilibrium nonlinear optical absorption in semiconductor superlattices}}}, doi = {{10.1063/1.114831}}, volume = {{67}}, year = {{1995}}, } @article{43589, author = {{Meier, Torsten and Kuhl, J. and Mayer, E.J. and Smith, G.O. and Bott, K. and Schulze, A. and Heuckeroth, V. and Heller, O. and Cundiff, S.T. and Bennhardt, D. and Koch, S.W. and Thomas, P. and Hey, R. and Ploog, K.}}, journal = {{Laser Physics}}, number = {{3}}, pages = {{616--620}}, publisher = {{INTERPERIODICA}}, title = {{{Transient degenerate four-wave-mixing on excitons in GaAs quantum wells}}}, volume = {{5}}, year = {{1995}}, } @inproceedings{43604, author = {{Meier, Torsten and Kuhl, J. and Mayer, E.J. and Smith, G.O. and Schulze, A. and Bennhardt, D. and Koch, S.W. and Thomas, P. and Hey, R. and Ploog, K.}}, booktitle = {{Proceedings of the 22nd International Conference on the Physics of Semiconductors ICPS}}, editor = {{Lockwood, D.J.}}, location = {{Vancouver, Canada}}, pages = {{1776--1779}}, publisher = {{World Scientific}}, title = {{{Biexciton Contributions to the Excitonic Nonlinearity in GaAs Quantum Wells}}}, year = {{1995}}, } @inproceedings{43451, author = {{Meier, Torsten and Feldmann, J. and Koch, M. and von Plessen, G. and Stolz, W. and Thomas, P. and Göbel, E.O.}}, booktitle = {{Proceedings of the 22nd International Conference on the Physics of Semiconductors ICPS}}, editor = {{Lockwood, D.J.}}, location = {{Vancouver, Canada}}, pages = {{1296--1303}}, publisher = {{World Scientific}}, title = {{{Coherent dynamics of exciton wave packets in quantum wells and superlattices}}}, year = {{1995}}, } @article{43452, abstract = {{We report time-resolved degenerate four-wave-mixing experiments on a high-quality single GaAs quantum well. The signals for parallel and cross-polarized exciting pulses show pronounced quantum beats with different frequencies corresponding to the heavy/light-hole splitting and the biexciton binding energy, respectively. Comparison of the experimental data with solutions of the optical Bloch equations for a phenomenological model system shows that these features result from strong contributions of the biexcitonic state. The importance of biexcitons to the nonlinear coherent response of the two-dimension exciton is further confirmed by the frequency dependence of the time-integrated four-wave-mixing signal amplitudes measured for the two polarization geometries.}}, author = {{Meier, Torsten and Mayer, E.J. and Smith, G.O. and Heuckeroth, V. and Kuhl, J. and Bott, K. and Schulze, A. and Koch, S.W. and Thomas, P. and Hey, R. and Ploog, K.}}, journal = {{Physical Review B}}, number = {{16}}, pages = {{10909--10914}}, publisher = {{American Physical Society}}, title = {{{Polarization dependence of beating phenomena at the energetically lowest exciton transition in GaAs quantum wells}}}, doi = {{10.1103/PhysRevB.51.10909}}, volume = {{51}}, year = {{1995}}, } @inbook{43520, author = {{Schroeter-Wittke, Harald}}, booktitle = {{Frömmigkeit und Freiheit. Theologische, ethische und seelsorgerliche Anfragen. Hans-Dieter Bastian zum 60. Geburtstag}}, editor = {{Wintzer, Friedrich and Schröer, Henning and Heide, Johannes}}, pages = {{93--116}}, publisher = {{CMZ-Verlag}}, title = {{{Das geht zu z/weit. Frömmigkeit und Blasphemie als Problem theologischer Ästhetik}}}, year = {{1995}}, } @inbook{43517, author = {{Schroeter-Wittke, Harald and Fermor, Gotthard}}, booktitle = {{Was suchst du hier, Elia? Ein hermeneutisches Arbeitsbuch}}, editor = {{Grünwaldt, Klaus and Schroeter-Wittke, Harald}}, pages = {{308--319}}, publisher = {{CMZ-Verlag}}, title = {{{Sounds of Silence. Popmusikalische Kontrapunkte zu Elia}}}, year = {{1995}}, } @inbook{43518, author = {{Schroeter-Wittke, Harald}}, booktitle = {{Was suchst du hier, Elia? Ein hermeneutisches Arbeitsbuch}}, editor = {{Grünwaldt, Klaus and Schroeter-Wittke, Harald}}, pages = {{333--348}}, title = {{{Bist du's Elia? Streiflichter zum homiletischen Gebrauch der Elia-texte im 20. Jahrhundert}}}, year = {{1995}}, } @inbook{43519, author = {{Schroeter-Wittke, Harald}}, booktitle = {{Was suchst du hier, Elia? Ein hermeneutisches Arbeitsbuch}}, editor = {{Grünwaldt, Klaus and Schroeter-Wittke, Harald}}, pages = {{349--355}}, title = {{{Mit Elia Gottesdienst feiern. Anregungen zur liturgischen Gestaltung von Elia-Texten}}}, year = {{1995}}, } @book{43516, editor = {{Grünwaldt, Klaus and Schroeter-Wittke, Harald}}, isbn = {{9783870620202}}, pages = {{424}}, publisher = {{CMZ-Verlag}}, title = {{{Was suchst du hier, Elia? Ein hermeneutisches Arbeitsbuch. Werner H. Schmidt und Horst Seebass zum 60. geburtstag}}}, year = {{1995}}, } @article{43522, author = {{Schroeter-Wittke, Harald}}, journal = {{Zeitschrift für Gottesdienst und Predigt}}, number = {{1}}, pages = {{33--35}}, title = {{{Animation zum Schlafen. Predigt (Mk 4,26-29)}}}, volume = {{13}}, year = {{1995}}, } @misc{43521, author = {{Schroeter-Wittke, Harald}}, booktitle = {{Theologische Realenzyklopädie}}, pages = {{530--533}}, title = {{{Ostern/Osterfest/Osterpredigt II. Osterpredigt}}}, volume = {{25}}, year = {{1995}}, } @article{43581, abstract = {{The ultrafast dynamics of photoexcited carriers in semiconductor superlattices is studied theoretically on the basis of a Monte Carlo solution of the coupled Boltzmann transport equations for electrons and holes. The approach allows a kinetic description of the relevant interaction mechanisms such as intra- miniband and interminiband carrier-phonon scattering processes. The energy relaxation of photoexcited carriers, as well as their vertical transport, is investigated in detail. The effects of the multiminiband nature of the superlattice spectrum on the energy relaxation process are discussed with particular emphasis on the presence of Bloch oscillations induced by an external electric field. The analysis is performed for different superlattice structures and excitation conditions. It shows the dominant role of carrier–polar-optical-phonon interaction in determining the nature of the carrier dynamics in the low-density limit. In particular, the miniband width, compared to the phonon energy, turns out to be a relevant quantity in predicting the existence of Bloch oscillations.}}, author = {{Meier, Torsten and Rossi, F. and Thomas, P. and Koch, S.W. and Selbmann, P.E. and Molinari, E.}}, journal = {{Physical Review B}}, number = {{23}}, pages = {{16943--16953}}, publisher = {{American Physical Society}}, title = {{{Ultrafast carrier relaxation and vertical-transport phenomena in semiconductor superlattices: A Monte Carlo analysis}}}, doi = {{10.1103/PhysRevB.51.16943}}, volume = {{51}}, year = {{1995}}, } @article{43575, abstract = {{Optical transitions into discrete levels coupled to an optically active continuum lead to asymmetrical Fano lines in the linear absorption spectra, reflecting interference between the excitation channels. We investigate the corresponding four-wave-mixing spectra for the nonlinear optical response within a model of noninteracting electrons. Our results show that four-wave-mixing experiments provide a useful tool to identify Fano resonances.}}, author = {{Meier, Torsten and Schulze, A. and Thomas, P. and Vaupel, H. and Maschke, K.}}, journal = {{Physical Review B}}, number = {{20}}, pages = {{13977--13986}}, publisher = {{American Physical Society}}, title = {{{Signatures of Fano-resonances in four-wave mixing experiments}}}, doi = {{10.1103/PhysRevB.51.13977}}, volume = {{51}}, year = {{1995}}, } @inproceedings{43568, abstract = {{The effective dimensionality of excitons can be drastically changed by applying an alternating electric field. On the basis of a full three-dimensional description of both coherent and incoherent phenomena in anisotropic structures it is found that appropriate applied oscillating fields change the exciton wave function from anisotropic three dimensional to basically two dimensional. This effective-dimension change is caused by dynamic localization which leads to an increase of the exciton binding energy and of the corresponding oscillator strength.}}, author = {{Meier, Torsten and Rossi, F. and Je, K.-C and Hader, J. and Thomas, P. and Koch, S.W.}}, booktitle = {{Proceedings of IV International Conference on Optics of Excitons in Confined Systems}}, location = {{Cortona, Italy}}, pages = {{1693--1697}}, publisher = {{Kluwer Academic Publishers}}, title = {{{Linear and Non-linear Optical Properties of Semiconductor Superlattices: Excitonic and Field-Induced Effects}}}, doi = {{10.1007/BF02457265}}, volume = {{17}}, year = {{1995}}, } @inproceedings{43571, abstract = {{We study exciton ionization induced by an axial electric field in a strongly coupled GaAs/Al0.3 Ga0.7 As superlattice at low temperatures. The field-induced ionization times of the heavy-hole 1s exciton in the miniband field regime are determined from transient four-wave-mixing experiments and theoretical model calculations. They are found to lie between the field ionization times of excitons in bulk semiconductors, and in strongly confined quantum well systems.}}, author = {{Meier, Torsten and von Plessen, G. and Koch, M. and Feldmann, J. and Koch, S.W. and Thomas, P. and Göbel, E.O. and Goosen, K.W. and Kuo, J.M. and Kopf, R.F.}}, booktitle = {{Proceedings of IV International Conference on Optics of Excitons in Confined Systems}}, location = {{Cortona, Italy}}, pages = {{1759--1762}}, title = {{{Electric-Field-Induced Exciton Ionization in a GaAs/AlGaAs Superlattice}}}, doi = {{10.1007/BF02457276}}, volume = {{17}}, year = {{1995}}, } @inproceedings{44278, abstract = {{Transient four-wave mixing (TFWM) has been extensively used during the last few years to study exciton dynamics in semiconductors and in semiconductor heterostructures. These studies have provided significant insight into exciton dynamics in both ordered and disordered systems. There are, nevertheless, still certain aspects of the excitonic TFWM response that are not completely understood. In particular, a complete understanding of the polarization and intensity dependences of the signai strength, the decay of the time-integrated signal, and the temporal characteristics of the time-resolved signal has proven elusive. Recent theoretical and experimental work has indicated that exciton-exciton interactions are important.1·2 Such interactions include incoherent processes, such as excitation-induced dephasing, and the formation of biexcitons. Additionally, some of the phenomena result from disorder, making them sample dependent.}}, author = {{Meier, Torsten and Albrecht, T.F. and Schulze, A. and Koch, M. and Bott, K. and Feldmann, J. and Stolz, W. and Kuhl, J. and Mayer, E.J. and Koch, S.W. and Göbel, E.O. and Cundiff, S.T.}}, booktitle = {{Quantum Electronics and Laser Science Conference}}, isbn = {{1-55752-402-5}}, location = {{Baltimore, Maryland United States}}, publisher = {{Optical Society of America}}, title = {{{Quantum beats from biexcitons in narrow quantum wells: polarization and density dependence}}}, year = {{1995}}, } @inproceedings{44277, abstract = {{The appearance of quantum beats (QBs) between heavy-hole (hh) and light-hole (lh) excitons in GaAs quantum wells (QWs) has been observed in many degenerate-four- wave-mixing (DFWM) experiments with subpicosecond optical pulses. Although the variation of the beat amplitude and phase with polarization of the incident pulses was recognized early on, a consistent theoretical interpretation of exciton coherence for the case of simultaneous excitation of hh and lh excitons is still missing.}}, author = {{Meier, Torsten and Kuhl, J. and Mayer, E.J. and Smith, G.O. and Bott, K. and Heuckeroth, V. and Thomas, P. and Koch, M. and Hey, R. and Ploog, K.}}, booktitle = {{Quantum Electronics and Laser Science Conference}}, isbn = {{1-55752-402-5}}, location = {{Baltimore, Maryland United States}}, publisher = {{Optical Society of America}}, title = {{{Polarization dependence of quantum beats between light-hole and heavy-hole excitons in GaAs quantum wells}}}, year = {{1995}}, }