Helmholtz solitons at nonlinear interfaces

The evolution of Helmholtz solitons at the interface separating two Kerr-type media is described by means of a generalized nonlinear Helmholtz equation. The bright soliton solution for this equation and arbitrary media properties are presented. Numerical simulations show that, when there is only mismatch in the linear refractive index, Helmholtz solitons behave according to Snell's law. Also, the general reflection and refraction properties of optical solitons show features that cannot be captured in the paraxial theory.