  Valley degrees of freedom offer a potential resource for quantum information
processing if they can be effectively controlled. We discuss an optical
approach to this problem in which intense light breaks electronic symmetries of
a two-dimensional Dirac material. The resulting quasienergy structures may then
differ for different valleys, so that the Floquet physics of the system can be
exploited to produce highly polarized valley currents. This physics can be
utilized to realize a valley valve whose behavior is determined optically. We
propose a concrete way to achieve such valleytronics in graphene as well as in
a simple model of an inversion-symmetry broken Dirac material. We study the
effect numerically and demonstrate its robustness against moderate disorder and
small deviations in optical parameters.
