Coherent effects in photoexcited semiconductor superlattices with electric fields

A microscopic many-body theory is reviewed which allows one to compute the linear and nonlinear properties of photoexcited semiconductor superlattices in the presence of static and time-dependent electric fields applied in the growth direction. The theory includes the process of optical excitation, the Coulomb interaction among the carriers, carrier-phonon coupling, and the acceleration induced by the electric field. For static fields the influence of Coulomb effects, carrier relaxation, carrier-phonon scattering, and intra-and interband polarization dephasing on the Bloch-oscillation dynamics is analyzed. Furthermore, the observability of dynamic localization, which may occur for appropriately chosen alternating applied fields using optical spectroscopy, is discussed.