We experimentally study the scattering of guided matter waves on an amplitude-modulated optical lattice. We observe different types of frequency-dependent dips in the asymptotic output density distribution. Their positions are compared quantitatively with numerical simulations. A semiclassical model that combines local Floquet-Bloch bands analysis and Landau-Zener transitions provides a simple picture of the observed phenomena in terms of elementary Floquet photon absorption-emission processes and envelope-induced reflections. Finally, we propose and demonstrate the use of this technique with a bichromatic modulation to design a tunable subrecoil velocity filter. Such a filter can be transposed to all species since it does not rely on a specific internal level configuration of the atoms.

• Received 16 June 2012

DOI:https://doi.org/10.1103/PhysRevA.87.013623