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HL: Halbleiterphysik

HL 39: Ultrakurzzeitph
änomene I

HL 39.5: Vortrag

Donnerstag, 27. März 2003, 12:00–12:15, BEY/81

Coherent Control of Excitonic Polarization Detected in Pulse Transmission Experiments — •Tobias Voß, Hans Georg Breunig, Iryna Kudyk, Ilja Rückmann, and Jürgen Gutowski — Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee, 28359 Bremen

Coherent control of heavy-hole excitonic polarization is analyzed by sending a pair of phase-locked 100 fs laser pulses either through a 5 nm or a 10 nm ZnSe single-quantum-well. The transmitted pulses and the induced excitonic polarization are measured time-resolved by use of an up-conversion technique which provides a real-time resolution of less than 50 fs. For low excitation densities the coherent amplification or destruction of the linear excitonic polarization as well as the simultaneous absorption or amplification of the second pulse of the pulse pair is monitored. For increased excitation densities a strong excitation-induced dephasing of the excitonic polarization is found which leads to a strong reduction of the achievable contrast ratio of the coherent switching and strongly influences the switching behavior, i.e., a fine structure occurs in the coherent-control signal. In this case also biexcitonic effects are found and studied.