Spatial matter-wave interference via adiabatic recombination of atomic wave packets

We propose and analyze an all-optical atomic beam splitter based on a multistep adiabatic passage in a ``tripod'' atomic level configuration. The spatial interference patterns obtained may exhibit extremely fine structure due to splittings of many times the photon momentum. The visibility of the obtained interference pattern is also shown to exhibit collapses and revivals as the distance from the interaction region is varied.