  Light-manipulation of correlated electronic phases in solids offers the
tantalizing prospect of realizing electronic devices operating at the ultrafast
time-scale. In this context, the experimental realization of non-equilibrium
transitions from a metal to a band or Mott insulator has shown to be
particularly elusive. Using dynamical mean-field theory, we study a simple
model representing the main physical properties of the oxygen-enriched compound
LaTiO$_{3+x}$. By properly optimizing the photo-doping of electrons from a
low-energy band into the valence states of the system, we show it is possible
to induce a valence transition from a correlated metallic state to a Mott
insulator at ultrashort time scales and to contain the heating during this
process, with the final non-thermal valence insulator having almost the same
effective temperature of the starting metal.
