Cooperative Phenomena in Resonant Propagation

B. M. Chernobrod

F. T. Arecchi, E. Courtens

Phenomena of coherent resonant propagation can be considered as resulting from the cooperative interaction of a certain number of excited two-level systems. It is shown that these phenomena can be characterized by a specific "maximum cooperation number" and by the associated "cooperation time." These are defined for the superradiant state, but their meaning and usefulness can be extended to other situations. The alternative description of of superradiance as a spontaneous or as a stimulated effect is also discussed and it is shown that with the help of the new concepts, the Dicke quantum perturbative treatment can be reconciled with the semiclassical theories.

Nicolai G. Basov

Valery I. Rupasov

In the quantum process of stimulated Raman scattering (SRS), a laser photon propagating in a resonance medium undergoes multifold conversions into a Stokes photon and back. The nontrivial ``cooperative'' behavior of the Stokes component of light transmitted through the medium is proven to be completely determined by the interference of scattering amplitudes in different sub-channels of the Stokes channel, which obviously combines all the sub-channels with an odd number of photon conversions. The theory of superfluorescence is then derived as the limiting case of the SRS theory.

Sergey G. Rautian, B. M. Chernobrod

L. N. Novikov, V. G. Pokazan'ev, G. V. Skrotskiǐ