  We describe optimized coherent control methods for two-photon transitions in
atoms of a ladder-type three-state energy configuration. Our approach is based
on the spatial coherent control scheme which utilizes counter-propagating
ultrashort laser pulses to produce complex excitation patterns in an extended
space. Since coherent control requires constructive interference of constituent
transition pathways, applying it to an atomic transition with a specific energy
configuration requires specially designed laser pulses. Here, we show, in an
experimental demonstration, that the two-photon transition with an intermediate
resonant energy state can be coherently controlled and retrieved out from the
resonance-induced background, when phase-flipping of the laser spectrum near
the resonant intermediate transition is used. A simple reason for this behavior
is the fact that the transition amplitude function (to be added to give an
overall two-photon transition) changes its sign at the intermediate resonant
frequency, thus, by a proper spectral-phase programming, the excitation
patterns (or the position-dependent interference of the transition given as a
consequence of the spatial coherent control) are well isolated in space along
the focal region of the counter-propagating pulses.
