Regensburg 2000 – wissenschaftliches Programm

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SYUO: Ultrakurzzeitdynamik an Oberflächen

SYUO 4: Ultrakurzzeitdynamik III (1)

SYUO 4.2: Hauptvortrag

Donnerstag, 30. März 2000, 15:00–15:30, H45

Dephasing of Optical Induced Excitonic Coherences in Semiconductors — •Duncan G. Steel — The University of Michigan, Ann Arbor, MI/USA

Coherent optical induced excitation of excitons in semiconductor heterostructures leads to various kinds of excitonic coherences that decay due to various dephasing processes. These processes reflect decay due to energy relaxation in the system as well as so-called pure dephasing processes that result only in the loss of phase coherence with no accompanying state relaxation. These processes are experimentally studied by use of both high resolution frequency domain coherent nonlinear laser spectroscopy as well as transient techniques including the stimulated photon echo and homodyne detected four-wave mixing. The methods have remarkable sensitivity that enable studies not only of single quantum well structures, but of single quantum dots. The measurements provide information not only on the mechanisms of the dephasing processes, but also show that in some cases, the nonlinear optical response is due to dephasing.