Parametric Three-Wave Soliton Generated from Incoherent Light

We show analytically and numerically that, under certain conditions, coherent localized structures can be generated and sustained from an incoherent source in quadratic nonlinear media. This phenomenon, which relies on the convection between the waves interacting in the medium, leads to the formation of a novel type of three-wave parametric soliton composed of both coherent and incoherent fields.