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Your search keyword '"Damen, T.C."' showing total 93 results
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93 results on '"Damen, T.C."'

1. Dissipative dynamics of an electronic wavepacket in a semiconductor double well potential

Author

Leo, Karl, Shah, J., Damen, T.C., Schulze, A., Meier, T., Schmitt-Rink, S., Thomas, P., Gobel, Ernst O., Shun Lein Chuang, Luo, M.S.C., Schafer, W., Kohler, K., and Ganser, P.

Subjects
Energy dissipation -- Research, Wave packets -- Research, Semiconductors -- Research, Quantum wells -- Research, Potential theory (Physics) -- Research, Business, Computers, Electronics, Electronics and electrical industries
Abstract

Double quantum-well structures (DQWs) and superlattice periodic arrays are analyzed in view of quantum mechanical resonance phenomena and tunneling. Optical experiments are shown to be suited to DQWs in illustrating coherent wavepacket dynamics and obtaining basic principles of quantum mechanics. Results show that the optically excited wavepacket as a function of applied electric field can be derived using simple principles while the wavepacket as a function of temperature is a more complicated relationship.

Published
1992

3. Subpicosecond four-wave mixing in GaAs/Al(x)Ga(1-x)As quantum wells

Author

Leo, K., Shah, J., Schmitt-Rink, S., Schäfer, W., Müller, J.F., Damen, T.C., Ganser, P., Göbel, E.O., Köhler, K., and Publica

Subjects
III-V semiconductors, zeitaufgelöste Photolumineszenz, heterostructure, III-V Halbleiter, time resolved photoluminescence, Heterostruktur
Abstract

We investigate the properties of coherent exciton states in GaAs/AlxGa1-xAs quantum wells using the four-wave-mixing technique with subpicosecond time resolution. In the first part of this work, we show that many-body interactions in a solid manifest themselves in a line shape of the four-wave-mixing signal that is substantially different from the predictions of the generally used simple two-level model. In particular, the coherent interaction of the quasiparticles leads to a signal at negative delay times, in agreement with recent theoretical predictions. In the second part, we report in detail about experiments where energetically close exciton transitions are excited coherently with a short laser pulse. The quantum or polarization interference leads to the observation of quantum beats in the decay of the diffracted signal. These results demonstrate that quantum-beat spectroscopy can be applied to study intrinsic excitations in solids.

Published
1991

4. Quantum beats of light hole and heavy hole excitons in quantum wells

Author

Damen, T.C., Köhler, K., Leo, K., Shah, J., and Publica

Subjects
III-V semiconductors, quantum wells, zeitaufgelöste Photolumineszenz, time-resolved photoluminescence, gekoppelte Quantum Wells, III-V Halbleiter, coupled quantum wells
Abstract

We report the first observation of quantum beats due to the interference of the polarization decay of heavy hole and light hole excitons in semiconductor quantum wells.

Published
1990

5. Quantum beats of free and bound excitons in GaAs/Al(x)Ga(1-x)As quantum wells

Author

Leo, K., Shah, J., Köhler, K., Damen, T.C., and Publica

Subjects
PL, tunneln, tunnelling, III-V semiconductors, quantum wells, tunneling, time resolved PL, gekoppelte Quantum Wells, photoluminescence, III-V Halbleiter, coupled quantum wells, Zeitaufgelöste PL
Abstract

We report the observation of quantum beats in the decay of the coherent polarization of intrinsic excitations in GaAs/GaAlAs quantum wells. The beating arises from interference of excitons with slightly different quantum confinement energy due to well-width fluctuations.

Published
1990

6. Tunneling in semiconductor heterostructures studied by subpicosecond four-wave mixing

Author

Damen, T.C., Ganser, P., Göbel, E.O., Köhler, K., Leo, K., Shah, J., and Publica

Subjects
tunneln, III-V semiconductors, quantum wells, zeitaufgelöste Photolumineszenz, time-resolved photoluminescence, gekoppelte Quantum Wells, III-V Halbleiter, coupled quantum wells, tunnelung
Abstract

We apply time-resolved four-wave mixing as novel tool to study resonant tunneling of carriers in semiconductor heterostructures. The polarization decay of excitons in a quantum well is much faster when the alignment of the electron levels in adjacent wells leads to resonant tunneling and subsequent scattering of the carriers.

Published
1990

18. Femtosecond Transient-Grating Experiments in Quantum Wells

Author

Leo, Karl, primary, Göbel, Ernst O., additional, Damen, T.C., additional, Shah, Jagdeep, additional, Schmitt-Rink, S., additional, Schäfer, W., additional, Stafford, C., additional, Müller, J.F., additional, Köhler, K., additional, and Ganser, P., additional

Published
1990
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20. Outdoor BLAST Measurement System at 2.44 GHz: Calibration and Initial Results.

Author

Gans, Michael J., Amitay, Noach, Yu Shuan Yeh, Hao Xu, Damen, T.C., Valenzuela, Reinaldo A., Sizer, Theodore, Storz, R., Taylor, D., MacDonald, W.M., Cuong Tran, and Adamiecki, Andrew

Subjects
CALIBRATION, SPACETIME, WIRELESS communications, TELECOMMUNICATION systems, DIGITAL communications
Abstract

Reports the calibration and initial results of outdoor Bell-Labs Layered Space-Time measurement system at 2.44 gigahertz. Background on the wireless communication technique; Description of the measurement system; Conclusion.

Published
2002
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21. Propagation measurements for fixed wireless loops (FWL) in a suburban region with foliage and terrain blockages.

Author

Gans, M.J., Amitay, N., Yeh, Y.S., Damen, T.C., Valenzuela, R.A., Choelhang Cheon, and Jeho Lee

Abstract

We present the results of propagation measurements at 2.485 GHz for fixed wireless loops. Path loss measurements were performed and characterized at 43 subscriber locations around a base station antenna located on top of Crawford Hill in Holmdel, NJ. This suburban location is characterized by rolling hills, foliage, and terrain blockages. Temporal and horizontal motion path loss fluctuations were found to be uncorrelated, each characterized by a different Ricean distribution. Lower r.m.s. delay spreads were obtained with directive subscriber antennas than with omni-directional antennas. No substantial gain loss (less than 2 dB) of subscribers' directive antennas was observed. The effects of trees, with foliage, surrounding the base station upon the path loss and the ratio of scattered power to specular power are also examined. The distance exponent of path loss versus distance (about 1.5) was observed to be less than free-space. Diffraction loss from hilltop trees, shadowing the base station, are suspected to be the cause. This loss decreases as the remote moves further away and comes out of the shadow. Scattered power from directions other than line-of-sight was observed to be as high as one half of the specular contribution when tree scattering near the base station was significant [ABSTRACT FROM PUBLISHER]

Published
2002
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24. Spin relaxation and thermalization of excitons in GaAs quantum wells.

Author

Damen, T.C., Leo, Karl, Shah, Jagdeep, and Cunningham, J.E.

Subjects
*QUANTUM wells, *EXCITON theory
Abstract

Studies the spin relaxation and thermalization of excitons in GaAs quantum wells. Spin relaxation time constants for resonant and nonresonant excitons; Exciton-acoustic phonon energy exchange rates.

Published
1991
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25. Time-resolved study of carrier capture and recombination in monolayer Be delta-doped GaAs.

Author

Damen, T.C. and Fritze, M.

Subjects
*ELECTRODYNAMICS, *RADIOACTIVE decay, *ELECTRON gas
Abstract

Examines the subpicosecond dynamics of carrier capture and decay in beryllium (Be) delta-doped gallium arsenide structures. Dependence of luminescence decay rates on hole energy in two-dimensional Fermi gas; Change in the spatial electron-hole overlap resulting from band-mixing effects; Attribution of Be density fluctuations to carrier localization.

Published
1995
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