SKM 2023 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 35: Focus Session: Transient multi-wave mixing on excitonic resonances

HL 35.9: Vortrag

Donnerstag, 30. März 2023, 13:15–13:30, POT 251

Multi-photon pump probe of magnetic-field-induced quantum beats in Cu₂O — •Nikita V. Siverin, Andreas Farenbruch, Dietmar Fröhlich, Dmitri R. Yakovlev und Manfred Bayer — TU Dortmund, Dortmund, Germany

Multi-photon processes such as second harmonic generation are suitable for the investigation of exciton symmetries by analyzing the linear polarization angles of the incoming and the outgoing light. We use difference frequency generation (DFG) with two-photon as the optical technique. The initial laser pulse excites an exciton population by a two-photon excitation process. Probe pulse stimulates a DFG photon. Delaying the second pulse in time enables us the measurement of exciton coherence times and quantum beats between several states. There is also an additional degree of freedom compared to the SHG technique in the polarization of the emission channel. We measure the coherence time of yellow series in Cu₂O. By applying a magnetic field up to 10T in Voigt geometry the 1S orthoexciton splits into three states denoted by the quantum number M = -1,0,1. We observe a beating between these three states. By a selection of the linear polarization setting in the emission channel one can deliberately choose to detect single-frequency beats between the M=+1 and M=-1, triple-frequency beats between all three states or only the M=0 state without beats. Beat frequencies scale with magnetic field strength.