Resonantly absorbing one-dimensional photonic crystals

A compact theoretical description of the effects of dissipation on the propagation of light waves through amultilayer periodic mirror built from resonant absorbing atoms is presented. Depending on the lattice periodicity,ultranarrow photonic gaps, weak polaritonic gaps, as well as rather atypical gap structures may beobserved. Because of the atom's absorption line shape Bloch gap modes may acquire quite a cumbersomestructure which is thoroughly studied here or which may even disappear when dissipation becomes sufficientlystrong. The same approach well applies also to resonantly absorbing photonic crystals based on excitonicresonances.