New results on high-field transport in semiconductor superlattices

The optical properties of an electrically biased semiconductor superlattice are strongly influenced by coupling to other bands. As these coupling mechanisms depend on the strength of the applied electric field, we find a distinct variation in transition line broadening, dephasing time and spatial extension of the wavefunction. The fundamental Bloch-oscillating transport in a periodic structure is drastically modified and exhibits a strong damping with a surprising revival of polarization coherence which reappears on a picosecond scale.