Regensburg 1998 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 24: Poster II

HL 24.46: Poster

Mittwoch, 25. März 1998, 10:30–19:00, A

Nonlinear Absorption and Pulse Propagation in ZnSe — •Q.Y. Peng, G. Manzke, U. Moldzio, and K. Henneberger — Fachbereich Physik, Universit"at Rostock, Universit"atsplatz 3, D-18051 Rostock

The optical properties of bulk ZnSe are investigated in a large range of density and temperature. Solving the semiconductor Bloch equation for a weak probe pulse including dynamical screening and both carrier-carrier and carrier-polarization scattering [1], we present the nonlinear absorption spectra of excitons. The influence of the center-of-mass motion of the electron-hole pair on the susceptibility is taken into account describing the effect of spatial dispersion. This enables us to determine the nonlinear effects in the polariton dispersion including the band edge absorption in contrast to a simple oscillator model. Finally we study the nonlinear behaviour of polariton beats observed in pulse propagation experiments in ZnSe/ZnS_xSe_1−x microstructures [2]. We find, that absorption above the band edge decreases the slope of the excitonic branch of the polariton dispersion and correspondingly the frequency of the polariton beats.

[1] G. Manzke, Q.Y Peng, U. Moldzio, and K. Henneberger,
phys. stat. sol.(b), accepted.

[2] U. Neukrich, K. Wundke, Phys. Rev. B55, 15408 (1997).