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Spatio-temporal dynamics of optical nonlinearities in semiconductor quantum wells

Title data

Axt, Vollrath M. ; Kuhn, Tilmann ; Siantidis, K. ; Grosse, S. ; Koch, M. ; Feldmann, Jochen ; Stolz, Wolfgang:
Spatio-temporal dynamics of optical nonlinearities in semiconductor quantum wells.
In: Tsen, Kong-Thon (ed.): Ultrafast Phenomena in Semiconductors III. - Bellingham, WA , 1999 . - pp. 68-78 . - (Proceedings / SPIE, International Society for Optical Engineering ; 3624 )
ISBN 0-8194-3094-3
DOI: https://doi.org/10.1117/12.349282

Project information

Project financing: Deutsche Forschungsgemeinschaft
European Union network Ultrafast Quantum Optoelectronics (FMRX-CT97-0134) and HLRZ Jülich

Abstract in another language

We present results of the optically excited dynamics in semiconductor quantum wells on short length and time scales. Nonlinear optical experiments are performed with high temporal and high spatial resolution. To interpret the experimental findings calculations are performed on different approximation levels. Two different time regimes are investigated: in the incoherent time regime we study the dynamics of heating, cooling, and the formation of excitons by measuring the temporal behavior of the lateral expansion rate of locally created electron-hole pairs or excitons. A monomolecular exciton formation process is found. The experimental results in this regime are well reproduced by the Boltzmann equation for incoherent exciton densities with phenomenological scattering rates. In addition we have performed a microscopic density matrix analysis for the heating scenario where we have modeled explicitly the initial transformation of coherent excitations into incoherent exciton densities. It is found that the heating due to scattering with acoustic phonons gives reasonable agreement with the observed rates. In the coherent time regime a spatio-temporal beating is observed. This unexpected non-monotonic modulation of the spatial width arises from excitonic wave-packets which modulate the detected lateral profile of the optical nonlinearity in a characteristic way. It is explained by the superposition of various signal components which are detected simultaneously due to the collinearity of our experiment. This effect is illustrated by calculations using a simplified model on the Hartree-Fock level.

Further data

Item Type: Article in a book
Refereed: Yes
Keywords: excitons; Semiconductors; laser excitation; ultrafast dynamics; non-linear optics; pump probe; exciton wave paket
Institutions of the University: Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Theoretical Physics III > Chair Theoretical Physics III - Univ.-Prof. Dr. Martin Axt
Faculties
Faculties > Faculty of Mathematics, Physics und Computer Science
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Theoretical Physics III
Result of work at the UBT: No
DDC Subjects: 500 Science > 530 Physics
Date Deposited: 25 Oct 2017 05:44
Last Modified: 06 Jun 2019 13:25
URI: https://eref.uni-bayreuth.de/id/eprint/40033