@article{40321,
  author       = {{Behrens, Ulrike and Kitzerow, Heinz-Siegfried}},
  issn         = {{1042-7147}},
  journal      = {{Polymers for Advanced Technologies}},
  keywords     = {{Polymers and Plastics}},
  number       = {{8}},
  pages        = {{433--437}},
  publisher    = {{Wiley}},
  title        = {{{Utility of a liquid crystalline diacrylate for bistable switching cholesteric gel displays}}},
  doi          = {{10.1002/pat.1994.220050806}},
  volume       = {{5}},
  year         = {{1994}},
}

@article{40318,
  author       = {{Jain, Sukhmal C. and Kitzerow, Heinz-Siegfried}},
  issn         = {{0003-6951}},
  journal      = {{Applied Physics Letters}},
  keywords     = {{Physics and Astronomy (miscellaneous)}},
  number       = {{22}},
  pages        = {{2946--2948}},
  publisher    = {{AIP Publishing}},
  title        = {{{Bulk‐induced alignment of nematic liquid crystals by photopolymerization}}},
  doi          = {{10.1063/1.111419}},
  volume       = {{64}},
  year         = {{1994}},
}

@article{42055,
  author       = {{Herzog, Bernd and Huber, Klaus and Rennie, Adrian R.}},
  issn         = {{0021-9797}},
  journal      = {{Journal of Colloid and Interface Science}},
  keywords     = {{Colloid and Surface Chemistry, Surfaces, Coatings and Films, Biomaterials, Electronic, Optical and Magnetic Materials}},
  number       = {{2}},
  pages        = {{370--381}},
  publisher    = {{Elsevier BV}},
  title        = {{{Characterization of Worm-like Micelles Containing Solubilized Dye-Molecules by Light Scattering Techniques}}},
  doi          = {{10.1006/jcis.1994.1179}},
  volume       = {{164}},
  year         = {{1994}},
}

@article{42054,
  author       = {{Maloney, Colette and Huber, Klaus}},
  issn         = {{0021-9797}},
  journal      = {{Journal of Colloid and Interface Science}},
  keywords     = {{Colloid and Surface Chemistry, Surfaces, Coatings and Films, Biomaterials, Electronic, Optical and Magnetic Materials}},
  number       = {{2}},
  pages        = {{463--470}},
  publisher    = {{Elsevier BV}},
  title        = {{{Mixtures of Polyacrylic Acid and Nonionic Surfactants at the Water/Air Interface}}},
  doi          = {{10.1006/jcis.1994.1189}},
  volume       = {{164}},
  year         = {{1994}},
}

@inbook{43514,
  author       = {{Schroeter-Wittke, Harald}},
  booktitle    = {{Gottesdienstpraxis. Serie A. IV. Perikopenreihe Band 2}},
  editor       = {{Domay, Erhard}},
  pages        = {{128--135}},
  title        = {{{4. Sonntag nach Trinitatis. Predigttext: 1. Petrus 3,8-15a(15b-17)}}},
  year         = {{1994}},
}

@inbook{43597,
  abstract     = {{Transient four-wave mixing (TFWM) experiments have been widely used to study the excitation dynamics of excitons in quantum wells [1]. Recently is has been observed that TFWM signals, especially quantum beats between heavy-hole (hh) and light-hole (lh) excitons, strongly depend on the polarization of the incident laser pulses [2–6]. This dependence is presently being investigated.}},
  author       = {{Meier, Torsten and Bennhardt, D. and Thomas, P. and Hu, Y.Z. and Binder, R. and Koch, S.W.}},
  booktitle    = {{Coherent Optical Interactions in Semiconductors}},
  editor       = {{Phillips, R.T.}},
  issn         = {{978-1-4757-9750-3}},
  pages        = {{349--354}},
  publisher    = {{Springer Science+Business Media}},
  title        = {{{Theory of polarization-dependent four-wave mixing using the optical Bloch equations}}},
  doi          = {{10.1007/978-1-4757-9748-0_26}},
  year         = {{1994}},
}

@inproceedings{44283,
  abstract     = {{The strong influence of exciton/exciton interaction on the nonlinear optical response of the 2D exciton in GaAs quantum wells has been demonstrated in several recent experimental studies. The theoretical model for the microscopic coupling mechanism is still the subject of controversy, however. In ref. [1], we have presented a model including a density dependent coupling between opposite spin excitons which assumes that the interaction results in a renormalization of the matrix elements, dephasing rates and energies of the transition from the single-exciton state to the two-exciton state with respect to the corresponding quantities for the single exciton transitions. In contrast, Wang et al. claim that all experimental observations are explained by a density induced dephasing rate and that biexciton states play no role [2]. Here we present a new 3-pulse degenerate-four-wave-mixing (DFWM) configuration which is able to differentiate between pure local field effects and biexcitonic contributions to the time-integrated signal. Experiments were performed on an almost homogeneously broadened GaAs/Al0.3Ga0.7As single QW (well width 20 nm, photoluminescence line 0.3 meV, homogenous linewidth 0.15 meV) in the backward reflection geometry. The sample was cooled to 10 K and excited by a sequence of three pulses (1.1 ps duration) with equal intensity, wave vectors 𝑘→1,𝑘→2,𝑘→3
 and delays τ12 and τ13 between the second and first and the third and first pulse, respectively. The signal was monitored in the direction 𝑘→𝑠=𝑘→1+𝑘→2−𝑘→3
 which provides no signal for the chosen pulse length if local field and renormalization effects are negligible. The peak intensity of the time-integrated DFWM signal has been calculated by solving the optical Bloch for a system of two non-interacting two-level systems (2LS) with opposite circular polarization selection rules (local field effect) and for the renormalized four-level system (4LS) depicted in Fig. 1 which assumes the formation of biexcitons between excitons with opposite spins. The signal strength is proportional to the strength of the local field in the case of the 2LS and to the renormalization for the 4LS. The peak signal intensities expected for pure local field and pure biexction contributions are summarized in the second and third column of Table 1 for eight experimental configurations applying different linear and circularly polarized pulses. The values are normalized to the signal strength predicted for three parallel linearly polarized pulses. Close inspection of the data reveals remarkable differences of the peak amplitude with polarization geometry for the two coupling models.}},
  author       = {{Meier, Torsten and Kuhl, J. and Mayer, E.J. and Smith, G.O. and Bennhardt, D. and Schulze, A. and Thomas, P. and Hey, R. and Ploog, K.}},
  booktitle    = {{International Conference on Ultrafast Phenomena}},
  location     = {{California, United States}},
  title        = {{{Contributions of Bound and Unbound Two-Exciton States to the Nonlinear Optical Response of GaAs Quantum Wells}}},
  doi          = {{10.1364/UP.1994.MD.5}},
  year         = {{1994}},
}

@inproceedings{44284,
  abstract     = {{Several recent experimental and theoretical studies have demonstrated the importance of exciton/exciton coupling due to Coulomb interactions for the nonlinear optical response of the 2D exciton in GaAs quantum wells (QWs).1,2 These results imply that multilevel models are required in order to provide a theoretically appropriate description of the nonlinear behavior. Previous application of a renormalized 9-level system has proven successful in describing the third-order response of hh-excitons in GaAs quantum wells.2 We present a comprehensive experimental and theoretical investigation of the polarization selection rules for degenerate- four-wave-mixing (DFWM) and quantum beating of hh and lh transitions in a GaAs QW. Depending on the polarization and temporal sequence of the three pulses simultaneous excitation of the hh and lh transitions generates either quantum beats (QB), no modulation of the signal, or a superposition of QB and polarization interference (PI) effects as proved by spectrally resolved (SR)-DFWM.}},
  author       = {{Meier, Torsten and Mayer, E.J. and Smith, G.O. and Kuhl, J. and Schulze, A. and Bennhardt, D. and Koch, S.W. and Thomas, P. and Hey, R. and Ploog, K.}},
  booktitle    = {{Proceedings of the 5th European Quantum Electronics Conference}},
  location     = {{Amsterdam, Netherlands}},
  pages        = {{187--188}},
  title        = {{{Polarization selection rules for quantum beating between light and heavy holes in GaAs quantum wells}}},
  year         = {{1994}},
}

@inproceedings{44282,
  abstract     = {{Although the importance of exciton/exciton interactions for the nonlinear optical response of GaAs quantum wells (QW) is well established by many experimental observations, the role of biexciton states in these processes is still an open question, even at low excitation densities. Evidence for the formation of biexcitons has been independently derived from pump-probe studies [1], from the density dependence of the photoluminescence (PL) line shape [2] and from signal modulations observed in degenerate-four-wave-mixing (DFWM) with incoherent light pulses [3]. Here, we report on time-resolved DFWM with parallel (PP) and cross-polarized (CP) pulses. Depending on the polarization geometry, the signals reveal strong quantum beats which correspond to the splitting between either the heavy hole (hh) and light hole (lh) exciton or the hh exciton and the biexciton.}},
  author       = {{Meier, Torsten and Mayer, E.J. and Smith, G.O. and Kuhl, J. and Bennhardt, D. and Schulze, A. and Thomas, P. and Hey, R. and Ploog, K.}},
  booktitle    = {{International Conference on Ultrafast Phenomena}},
  location     = {{California, United States}},
  title        = {{{Observation of Biexcitons in Time-Resolved Degenerate-Four-Wave-Mixing on GaAs Quantum Wells}}},
  year         = {{1994}},
}

@inproceedings{44279,
  abstract     = {{The strong nonlinear optical response of the 2D exciton in GaAs quantum wells at relatively low excitation densities has been observed in many experimental studies in accordance with theoretical predictions. In principle, exciton/exciton interaction results in a renormalization of the transition matrix elements, dephasing rates and frequencies of the excitonic states. Wang et al.1 claimed that all experimental results can be explained by a density- induced enhanced dephasing rate. In a previous paper,2 we have suggested a density dependent coupling between opposite spin excitons, which involves all three renormalization phenomena.}},
  author       = {{Meier, Torsten and Smith, G.O. and Mayer, E.J. and Kuhl, J. and Schulze, A. and Bennhardt, D. and Koch, S.W. and Thomas, P. and Hey, R. and Ploog, K.}},
  booktitle    = {{European Quantum Electronics Conference}},
  location     = {{Amsterdam, Netherlands}},
  title        = {{{Direct verification of the existence of biexcitons in GaAs qauntum wells}}},
  year         = {{1994}},
}

@techreport{45230,
  author       = {{Tulodziecki, G. and Herzig, Bardo}},
  publisher    = {{FB 2, Universität Paderborn}},
  title        = {{{Hinweise zur Statistik. Arbeitspapier}}},
  year         = {{1994}},
}

@inproceedings{8089,
  author       = {{Krauter, Stefan and Hanitsch, Rolf}},
  booktitle    = {{Proceedings of the Cairo International Conference of Renewable Energy Sources, Kairo (Ägypten), 30. Dezember 1992 – 2. Januar 1993}},
  title        = {{{Calculating the Influence of Skylight-Polarization on the Transmission of Encapsulations of PV-Modules}}},
  year         = {{1993}},
}

@inproceedings{11904,
  abstract     = {{This paper gives a status report of the Philips research system for phoneme-based, large-vocabulary, continuous-speech recognition. Like for many other systems, the recognition architecture is based on an integrated statistical approach. We describe the characteristic features of the system as opposed to other systems: 1. The Viterbi criterion is consistently applied both in training and testing. 2. Continuous mixture densities are used without tying or smoothing. 3. Time-synchronous beam search in connection with a phoneme look-ahead is applied to a tree-organized lexicon. The system has been successfully applied to the American English DARPA RM task. Here, we report experimental results for a German 13 000-word Philips internal dictation task. In addition to the scientific prototype, a PC version has been set up which is described here for the first time.}},
  author       = {{Steinbiss, Volker and Ney, Hermann and Haeb-Umbach, Reinhold and Train, B.-H. and Essen, U. and Kneser, Reinhard and Oerder, Martin and Meier, H. G. and Aubert, X. and Dugast, Christian and Geller, Dieter and Hoellerbauer, W. and Bartosik, H.}},
  booktitle    = {{EUROSPEECH, Berlin}},
  title        = {{{The Philips Research System for Large-Vocabulary Continuous-Speech Recognition}}},
  year         = {{1993}},
}

@article{35389,
  author       = {{Schnepp, W. and Disch, S. and Schmidt, Claudia}},
  issn         = {{0267-8292}},
  journal      = {{Liquid Crystals}},
  keywords     = {{Condensed Matter Physics, General Materials Science, General Chemistry}},
  number       = {{3}},
  pages        = {{843--852}},
  publisher    = {{Informa UK Limited}},
  title        = {{{<sup>2</sup>H NMR study on the lyomesophases of the system hexaethylene glycol dodecyl methyl ether/water Temperature dependence of quadrupole splittings}}},
  doi          = {{10.1080/02678299308027761}},
  volume       = {{14}},
  year         = {{1993}},
}

@article{35387,
  author       = {{Rosen, M. E. and Rucker, S. P. and Schmidt, Claudia and Pines, A.}},
  issn         = {{0022-3654}},
  journal      = {{The Journal of Physical Chemistry}},
  keywords     = {{Physical and Theoretical Chemistry, General Engineering}},
  number       = {{15}},
  pages        = {{3858--3866}},
  publisher    = {{American Chemical Society (ACS)}},
  title        = {{{Two-dimensional proton NMR studies of the conformations and orientations of n-alkanes in a liquid-crystal solvent}}},
  doi          = {{10.1021/j100117a037}},
  volume       = {{97}},
  year         = {{1993}},
}

@article{40003,
  author       = {{Kitzerow, Heinz-Siegfried and Crooker, P. P.}},
  issn         = {{0267-8292}},
  journal      = {{Liquid Crystals}},
  keywords     = {{Condensed Matter Physics, General Materials Science, General Chemistry}},
  number       = {{1}},
  pages        = {{31--43}},
  publisher    = {{Informa UK Limited}},
  title        = {{{Electric field effects on the droplet structure in polymer dispersed cholesteric liquid crystals}}},
  doi          = {{10.1080/02678299308029051}},
  volume       = {{13}},
  year         = {{1993}},
}

@article{40005,
  author       = {{Kitzerow, Heinz-Siegfried and Schmid, H. and Ranft, A. and Heppke, G. and Hikmet, R. A. M. and Lub, J.}},
  issn         = {{0267-8292}},
  journal      = {{Liquid Crystals}},
  keywords     = {{Condensed Matter Physics, General Materials Science, General Chemistry}},
  number       = {{3}},
  pages        = {{911--916}},
  publisher    = {{Informa UK Limited}},
  title        = {{{Observation of blue phases in chiral networks}}},
  doi          = {{10.1080/02678299308027768}},
  volume       = {{14}},
  year         = {{1993}},
}

@article{40074,
  author       = {{Dolganov, V. K. and Lourie, O. R. and Heppke, G. and Kitzerow, Heinz-Siegfried}},
  issn         = {{1155-4312}},
  journal      = {{Journal de Physique II}},
  keywords     = {{Physics and Astronomy (miscellaneous), General Engineering, Atomic and Molecular Physics, and Optics}},
  number       = {{7}},
  pages        = {{1087--1096}},
  publisher    = {{EDP Sciences}},
  title        = {{{Anomalies of the temperature dependence of electrostriction in blue phases}}},
  doi          = {{10.1051/jp2:1993185}},
  volume       = {{3}},
  year         = {{1993}},
}

@article{40071,
  author       = {{Kitzerow, Heinz-Siegfried and Crooker, P. P.}},
  issn         = {{1155-4312}},
  journal      = {{Journal de Physique II}},
  keywords     = {{Physics and Astronomy (miscellaneous), General Engineering, Atomic and Molecular Physics, and Optics}},
  number       = {{5}},
  pages        = {{719--726}},
  publisher    = {{EDP Sciences}},
  title        = {{{UV-cured cholesteric polymer-dispersed liquid crystal display}}},
  doi          = {{10.1051/jp2:1993162}},
  volume       = {{3}},
  year         = {{1993}},
}

@inproceedings{40516,
  author       = {{Molsen, H. and Bardon, R. and Kitzerow, Heinz-Siegfried}},
  booktitle    = {{SID Conference Proceedings, 13th International Display Research Conference}},
  pages        = {{113--116}},
  publisher    = {{Society for Information Display (SID)}},
  title        = {{{Electrooptics of Polymer-Dispersed Ferroelectric Liquid Crystals}}},
  year         = {{1993}},
}