  We consider the coupled electromagnetic waves propagating in a nonlinear
coupler and in nonlinear waveguide array, which consists of alternating
waveguides of positive and negative refraction indexes. The forward wave and
backward wave interaction is realized in these devices. Gap solitons in a
nonlinear oppositely directional coupler with one channel or both channels
fabricated from nonlinear medium having negative refraction index are
discussed. Generalization of the usually waveguide array is zigzag array. Due
to zigzag configuration there are interactions between both nearest and next
nearest neighboring waveguides exist. The system of evolution equations for
coupled waves has the steady state solution describing the electromagnetic
pulse running in the array. Numerical simulation demonstrates robustness of
these solitary waves.
