  We systematically study the optical field localization in an active
three-dimensional (3D) disordered percolating system with light nanoemitters
incorporated in percolating clusters. An essential feature of such a hybrid
medium is that the clusters are combined into a fractal radiation pattern, in
which light is simultaneously emitted and scattered by the disordered
structures. Theoretical considerations, based on systematic 3D simulations,
reveal nontrivial dynamics in the form of propagation of localized field
bunches in the percolating material. We obtain the length of the field
localization and dynamical properties of such states as functions of the
occupation probability of the disordered clusters. A transition between the
dynamical states and narrow point-like fields pinned to the emitters is found.
The theoretical analysis of the fractal field properties is followed by an
experimental study of the light generation by nanoemitters incorporated in the
percolating clusters. The experimental results corroborate theoretical
predictions.
