TY - JOUR AU - Kitzerow, Heinz-Siegfried AU - Molsen, Henning AU - Heppke, Gerd ID - 40329 IS - 25 JF - Applied Physics Letters KW - Physics and Astronomy (miscellaneous) SN - 0003-6951 TI - Linear electro‐optic effects in polymer‐dispersed ferroelectric liquid crystals VL - 60 ER - TY - JOUR AU - Kitzerow, Heinz-Siegfried AU - Molsen, Henning AU - Heppke, Gerd ID - 40330 IS - 5 JF - Polymers for Advanced Technologies KW - Polymers and Plastics SN - 1042-7147 TI - Helical unwinding in polymer-dispersed ferroelectric liquid crystals VL - 3 ER - TY - JOUR AB - We investigated the switching behavior of the well-known antiferroelectric liquid crystal (R)-4-(1-methylheptyloxycarbonyl)phenyl-4'-octyloxybiphenyl-4-carboxylate (MHPOBC), embedded in a polymer matrix. The alignment of the liquid crystal in the UV-cured adhesive was controlled by mechanical shear during the polymerization-induced phase separation. Multistable switching with time constants down to 150 µs indicates that antiferroelectric PDLC devices are promissing for electrooptic application as flexible displays. AU - Molsen, Henning AU - Kitzerow, Heinz-Siegfried AU - Heppke, Gerd ID - 40328 IS - 8A JF - Japanese Journal of Applied Physics KW - General Physics and Astronomy KW - General Engineering SN - 0021-4922 TI - Antiferroelectric Switching in Polymer-Dispersed Liquid Crystals VL - 31 ER - TY - JOUR AU - Molsen, H. AU - Kitzerow, Heinz-Siegfried AU - Heppke, G. ID - 40515 JF - SID Digest of Technical Papers TI - Deformed-Helix Ferroelectric Effect in Polymer-Dispersed Ferroelectric Liquid Crystals VL - XXIII ER - TY - JOUR AU - Crooker, P. P. AU - Kitzerow, Heinz-Siegfried ID - 40514 JF - Condensed Matter News TI - Blue Phases VL - 1 ER - TY - JOUR AB - The authors present a detailed study of coherent tunneling oscillations of an optically excited electronic wavepacket in a semiconductor double quantum-well structure. The oscillation of the wavepacket between the two wells is traced by time-resolved pump-probe spectroscopy as well as time-resolved degenerate four-wave mixing. The experimental observations are compared with a simple theoretical model. The motion of the wave packet is studied as a function of both an external electric field and the lattice temperature. While the oscillation frequency shows the expected dependence on electric field, it increases with temperature at fixed electric field when perfectly delocalized electronic states exist at low temperature. AU - Meier, Torsten AU - Leo, K. AU - Shah, J. AU - Damen, T.C. AU - Schulze, A. AU - Schmitt-Rink, S. AU - Thomas, P. AU - Göbel, E.O. AU - Chuang, S.L. AU - Luo, M.S.C. AU - Schäfer, W. AU - Köhler, K. AU - Ganser, P. ID - 43444 IS - 10 JF - IEEE journal of quantum electronics SN - 0018-9197 TI - Dissipative Dynamics of an Electronic Wavepacket in a Semiconductor Double Well Potential VL - 28 ER - TY - JOUR AB - We report the study of optical dephazing of Wannier-Stark ladder excitations in a semiconductor superlattice by means of transient degenerate four-wave mixing. We observe pronounced modulations of the signal with a time period varying linearly with the electric field. The time period is found to equal the temporal periodicity of Bloch oscillations, in agreement with theory. In addition, we find that the dephazing time decreases with increasing localization of the Wannier-Stark states, which is attributed to carrier escape out of the lowest miniband. AU - Meier, Torsten AU - Feldmann, J. AU - Leo, K. AU - Shah, J. AU - Miller, D.A.B. AU - Cunningham, J.E. AU - von Plessen, G. AU - Schulze, A. AU - Thomas, P. AU - Schmitt-Rink, S. ID - 43443 IS - 11 JF - Physical Review B TI - Optical investigation of Bloch oscillations in a semiconductor superlattice VL - 46 ER - TY - JOUR AB - Femtosecond nonlinear laser spectroscopy is applied to study the dynamics of coherent optical excitations in semiconductors. In particular, excitonic excitations in quantum wells and superlattice structures are considered. Two examples demonstrate that four-wave mixing experiments with time-resolved detection of the nonlinear signal are able to distinguish between quantum beats and polarization interference.v 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. ID - 43445 IS - 1 JF - physica status solidi (b) TI - Time Resolved Four Wave Mixing in GaAs/AlAs Quantum Well Structures VL - 173 ER - TY - CONF AU - Hilleringmann, Ulrich AU - Adams, S AU - Goser, K ID - 39917 T2 - Proceedings ISSSE’92 TI - A Silicon Technology for Monolithic Integration of Optical Waveguides, Photodetectors and VLSI CMOS Circuits ER - TY - CONF AU - Adams, S AU - Hilleringmann, Ulrich AU - Goser, K ID - 39918 T2 - EFOC LAN TI - Electrooptical coupling of waveguides and VLSI circuits integrated on one silicon chip ER -