  We developed the theory of spin dependent transport through a spin-modulator
device (so-called Datta-and-Das spin transistor) in the presence of a
high-frequency electromagnetic field (dressing field). Solving the
Schr\"odinger problem for dressed electrons, we demonstrated that the field
drastically modifies the spin transport. In particular, the dressing field
leads to renormalization of spin-orbit coupling constants that varies
conductivity of the spin transistor. The present effect paves the way for
controlling the spin-polarized electron transport with light in prospective
spin-optronic devices.
