  We consider ballistic transport through a lateral, two-dimensional
superlattice with experimentally realizable, sinusoidally oscillating
Rashba-type spin-orbit interaction. The periodic structure of the rectangular
lattice produces a spin-dependent miniband structure for static SOI. Using
Floquet theory, transmission peaks are shown to appear in the mini-bandgaps as
a consequence of the additional, time-dependent SOI. A detailed analysis shows
that this effect is due to the generation of harmonics of the driving
frequency, via which e.g., resonances that cannot be excited in the case of
static SOI become available. Additionally, the transmitted current shows space
and time-dependent partial spin-polarization, in other words, polarization
waves propagate through the superlattice.
