Journal of Russian Laser Research 34
TWO-EXCITON STATES AND COHERENT THIRD-ORDER RESPONSE FROM SEMICONDUCTOR QUANTUM WELLS
Hoang Ngoc Cam
We present a microscopic description of the coherent third-order response from a quantum well treated
as a quasi-two-dimensional semiconductor in the exciton representation. We establish a closed system
of dynamic equations including those for coherent spin-polarized photons and excitons and for
correlated two-exciton structures, called molecules. Employing such a system of equations, we calculate
all third-order contributions to the semiconductor coherent polarization in the case where the
eigenenergies and eigenfunctions of the molecules are available. Considering the molecular problem,
we calculate the interaction potential between excitons in molecules for the investigated samples in the
limit of small exciton momentum taking place in the close-to-normal-incidence excitation geometry.
The potential computed allows an approximate explicit determination of the molecular eigenenergies
and eigenfunctions in the slow scattering limit. The criterion for a coherent pump-probe experiment
to support the limit is pointed out.