Approximate solutions and scaling transformations for quadratic solitons

We study quadratic solitons supported by two- and three-wave parametric int eractions in chi((2)) nonlinear media. Both planar and two-dimensional case s are considered We obtain very accurate, "almost exact," explicit analytic al solutions, matching the actual bright soliton profiles, with the help of a specially developed approach, based on analysis of the scaling propertie s. Additionally, we use these approximations to describe the linear tails o f solitary waves which are related to the properties of the soliton bound s tates.