Generation and manipulation of Bloch wave packets

We show how the spatial dynamics of a Bloch oscillating wave packet can directly be measured and manipulated by means of optical techniques. For excitation below and above the Wannier-Stark ladder (WSL) center, the wave packet performs harmonic oscillations, following the predictions of Zener; for excitation near the WSL center the wave packet is in the so-called breathing mode: a symmetric oscillation with virtually zero center of mass motion. How the position and line width of the excitation laser changes the initially excited wave packets and their dynamics will be discussed.