TY - JOUR AU - EBBERG, A AU - Noé, Reinhold AU - STOLL, L AU - SCHIMPE, R ID - 38496 IS - 5-6 JF - JOURNAL OF LIGHTWAVE TECHNOLOGY SN - 0733-8724 TI - A COHERENT OFDM SWITCHING-SYSTEM FOR FLEXIBLE OPTICAL NETWORK CONFIGURATION VL - 11 ER - TY - JOUR AU - Heppke, G. AU - Kitzerow, Heinz-Siegfried AU - Molsen, H. ID - 40327 IS - 1 JF - Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals KW - Condensed Matter Physics SN - 1058-725X TI - Electroclinic Effect in a Polymer-Dispersed Ferroelectric Liquid Crystal VL - 237 ER - TY - JOUR AU - Krüerke, D. AU - Kitzerow, Heinz-Siegfried AU - Heppke, G. AU - Vill, V. ID - 40324 IS - 10 JF - Berichte der Bunsengesellschaft für physikalische Chemie KW - General Chemical Engineering SN - 0005-9021 TI - First Observation of Selective Reflection and Blue Phases in Chiral Discotic Liquid Crystals VL - 97 ER - TY - JOUR AU - Baena, Maria J. AU - Buey, Julio AU - Espinet, Pablo AU - Kitzerow, Heinz-Siegfried AU - Heppke, Gerd ID - 40326 IS - 8 JF - Angewandte Chemie International Edition in English KW - General Chemistry KW - Catalysis SN - 0570-0833 TI - Metallomesogens with a Cholesteric Mesophase VL - 32 ER - TY - CONF AU - Brab, E. AU - Hilleringmann, Ulrich AU - Schumacher, K. ID - 39909 T2 - ESSCIRC ’93: Nineteenth European Solid-State Circuits Conference TI - Monolithic System Integration of Optical Devices, Photodetectors and Analog Transimpedance CMOS Amplifiers VL - 1 ER - TY - CONF AU - Schonstein, I. AU - Muller, J. AU - Hilleringmann, Ulrich AU - Goser, K. ID - 39910 T2 - ESSDERC ’93: 23rd European solid State Device Research Conference TI - Hot Carrier Monitoring in NMOS Transistors by Visible Light Emission ER - TY - CONF AU - Hilleringmann, Ulrich AU - Adam, S AU - Goser, K ID - 39913 T2 - ESSDtRC’93 TI - Micromechanic pressure sensors with optical readout and CMOS-preamplifiers on one silicon chip: Processing and first results ER - TY - JOUR AB - We present subpicosecond time-resolved four-wave-mixing studies on GaAs/AlAs short-period superlattices having different miniband widths. Photon echoes are observed as a consequence of the inhomogeneous broadening of the excitonic resonance. In addition, the photon-echo signal exhibits periodic modulations as a function of the time delay between the excitation laser pulses. Free excitons and excitons bound to neutral acceptors are identified as the underlying three-level system leading to the observed photon-echo quantum beats. From the beat period we can directly infer the dissociation energy of the bound exciton. In accordance with theory, we find that the dissociation energy decreases with increasing miniband width, i.e., when the excitons become less confined. In addition, we find that the dephasing rate of bound excitons is about one order of magnitude less than that of free excitons and is mainly determined by energy relaxation. AU - Meier, Torsten AU - Koch, M. AU - Weber, D. AU - Feldmann, J. AU - Göbel, E.O. AU - Schulze, A. AU - Thomas, P. AU - Schmitt-Rink, S. AU - Ploog, K. ID - 43449 IS - 3 JF - Physical Review B TI - Subpicosecond photon-echo spectroscopy on GaAs/AlAs short-period superlattices VL - 47 ER - TY - CHAP AB - Femtosecond nonlinear laser spectroscopy is applied to study the dynamics of coherent optical excitations in semiconductors. In particular, beat phenomena of excitonic excitations in quantum wells and superlattice structures will be considered. We will demonstrate that four wave mixing experiments with time resolved detection of the nonlinear signal are able to distinguish between quantum beats and polarization interference. In addition, we report for a GaAs/AlAs superlattice the observation of quantum beats in the photon echo signal. The occurence of these beats is attributed to the simultaneous excitation of bound and localized excitons. AU - Meier, Torsten AU - Göbel, E.O. AU - Koch, M. AU - Feldmann, J. AU - von Plessen, G. AU - Schulze, A. AU - Thomas, P. AU - Schmitt-Rink, S. AU - Köhler, K. AU - Ploog, K. ED - Lookwood, D. ED - Pinczuk, A. ID - 43442 SN - 978-94-010-4845-3 T2 - Optical Phenomena in Semiconductor Structures of Reduced Dimension TI - Time resolved Four Wave Mixing in GaAs/AlAs Quantum Well Structures ER - TY - JOUR AB - We report on the coherent dynamics of excitonic wave packets observed in transient four-wave mixing experiments on strained InGaAs/GaAs quantum-well structures. The excitonic noneigenstates are created by using laser pulses shorter than the electron round trip time within the exciton orbital. A characteristic temporal modulation of the diffracted signal is observed, which resembles the coherent dynamics of an electron wave packet in a hydrogen atom expected for the case of a simultaneous excitation of all bound and the lowest continuum states. AU - Meier, Torsten AU - Feldmann, J. AU - von Plessen, G. AU - Koch, M. AU - Göbel, E.O. AU - Thomas, P. AU - Bacher, G. AU - Hartmann, C. AU - Schweizer, H. AU - Schäfer, W. AU - Nickel, H. ID - 43448 IS - 20 JF - Physical review letters TI - Coherent Dynamics of Excitonic Wave Packets VL - 70 ER -