Abstract

On a time scale shorter than the periods of elementary excitations, e.g. phonons or plasmons, quantum kinetic phenomena play an important role for the ultrafast dynamics of optically excited semiconductors. Ultrafast spectroscopy with laser pulses as short as 20 fs allows a direct study of coherent optical polarizations and nonequilibrium carriers in this regime [1]. In this paper we demonstrate for the first time heavy hole (HH)-light hole (LH) quantum beats which originate from the coherent nonlinear coupling of interband polarizations between the respective valence and the conduction band in bulk GaAs. Our data directly show that the different interband transitions must be taken into account for a correct theoretical description of the optical response on a sub-100 fs time scale.

© 1996 IEEE