Theory of Self-Trapped Spatially Incoherent Light Beams

We present a modal theory of self-trapping spatially incoherent light beams in any general nonlinear media. We find that a self-trapped incoherent beam induces a multimode waveguide which guides the beam itself by multiply populating the guided modes. The self-trapping process alters the statistics of the incoherent beam, rendering it localized. We find the conditions for self-trapping (“existence region” in parameter space) and the correlation function of the incoherent self-trapped beam.