GAUSSIAN-BEAM TO SPATIAL SOLITON FORMATION IN KERR MEDIA

We present a detailed analysis of the generation and propagation of br ight spatial soliton beams in nonlinear Kerr media, in which an input beam is assumed to be of a Gaussian or hyperbolic secant form. The pro blem is solved by the use of the inverse-scattering transform (IST). T he analysis of the discrete spectrum obtained from the direct-scatteri ng problem gives exact information about the parameters of the generat ed soliton. A condition of soliton appearance in the spectrum as a fun ction of the complex width of the initial Gaussian beam is given numer ically. The similarities and differences between the hyperbolic secant and Gaussian beams entering the Kerr medium are analyzed in detail. A case is found in which almost all (approximately 99.5%) the total int ensity of the Gaussian beam entering the Kerr medium is transformed in to the soliton beam. However, this analogy to the self-trapping of sol iton beams occurs for higher total-intensity values than in the case o f the soliton input profile. The evolution from the Gaussian to the so liton envelope is studied and the condition of self-trapping in the ne ar field is found. The numerical method based on the IST of the soluti on to the nonlinear Schrodinger equation is refined.