  We investigate a photoinduced insulator-metal transition in the
Falicov-Kimball model with the dynamical mean-field theory (DMFT) extended to
nonequilibrium systems in periodic modulations in time. When the photon energy
of the pump light is $\Omega \approx U$ ($U$: the interaction strength), a
Drude-like peak is found to grow in the optical conductivity spectrum, which is
an evidence that the system is driven into a metallic state. During the
transition, the band gap does not collapse, whereas the distribution function
exhibits a non-monotonic behaviour away from the Fermi distribution. This
indicates that the transition cannot be accounted for by heating effects, but
creation of photo-carriers is responsible.
