  Photoinduced nonequilibrium states in the Mott insulators reflect the
fundamental nature of competition between itinerancy and localization of the
charge degrees of freedom. The spin degrees of freedom will also contribute to
the competition in a different manner depending on lattice geometry. We
investigate pulse-excited optical responses of a half-filled two-leg Hubbard
ladder and compare them with those of a one-dimensional extended Hubbard chain.
Calculating the time-dependent optical conductivity, we find that strong
mono-cycle pulse inducing quantum tunneling gives rise to anomalous suppression
of photo-induced in-gap weight, leading to negative weight. This is in contrast
to finite positive weight in the Hubbard chain. The origin of this anomalous
behavior in the two-leg ladder is attributed to photoinduced localized exciton
that reflects strong spin-singlet dimer correlation in the ground state.
