  We study numerically the photon emission from a semiconductor microcavity
containing $N\ge 2$ quantum wells under the influence of a periodic external
forcing. The emission is determined by the interplay between external forcing
and internal interaction between the wells. While the external forcing
synchronizes the periodic motion, the internal interaction destroys it. The
nonlinear term of the Hamiltonian supports the synchronization. The numerical
results show a jump of the photon intensity to very large values at a certain
critical value of the external forcing when the number of quantum wells is not
too large. We discuss the dynamics of the system across this transition.
