  A system of resonance atoms is placed in a medium with developed polariton
effect. In the spectrum of polariton states there can exist a band gap. If an
atom with a resonance frequency inside the polariton gap is incorporated into
the medium, the atomic spontaneous emission can be strongly suppressed. This is
what is called the localization of light. Nevertheless, an ensemble of
resonance atoms inside the polariton gap can radiate if their coherent
interaction is sufficiently strong. Conditions when coherent polariton
radiation can appear and the properties of this coherent polariton emission are
studied.
