Forward and backward optical waves in nonlinear metamaterials: Parametric processes

Propagation of the fundamental and third harmonic solitary waves in medium characterized by negative refraction index at the frequency of fundamental wave and by positive refractive index at the third harmonic frequency and simultons formation are considered. Gap soliton in a novel kind of nonlinear coupler with one channel or both channels fabricated from nonlinear medium having negative refraction index is found.