Cooperative superfluorescence in nanodusters

The features of superfluorescence (SF) in nanoclusters, which consist of a few neighboring particles interacting! with each other by exchange or/and electrostatic forces, are investigated theoretically. It is shown that there are two types of cooperative SF depending on the ratio between the linear size of a nanocluster and the cooperative interaction range. Experiments on cooperative luminescence in Ytterbium-doped silica fibers are analyzed. It is shown that the intensity of cooperative SF in such a system should be proportional to the fourth degree of Ytterbium concentration.