  We present Floquet-Keldysh non-equilibrium dynamical mean field calculations
(DMFT) with an iterative perturbative solver (IPT) for high pump-power induced
Stark states yielding a closing gap within semiconductor bulk and
nano-cavities. Our model predicts unusual broadening of bands in systems like
ZnO random lasers. This can be explained as an exciton-polariton coupling
within the single crystalline pillar meeting the Mie resonance condition.
Extraordinary enhancement of the lifetime of electronic states within the gap
can lead to stable lasing modes and gain narrowing.
