GRAY AND DARK MODES IN NONLINEAR WAVE-GUIDES

Propagation of light waves in a thin, self-defocusing, nonlinear film bounded by an infinite self-defocusing medium of a different nonlinearity is investigated. It is shown that both gray and dark solitary waves can be trapped in the film when the linear refractive index of the film, n(f), is smaller than that of the cladding, n(o), and the wave's effective index, n(e), is n(f) < n(e) < n(o). On the other hand, a series of trapped dark oscillatory solitary waves results when ne < min{n(f), n(o)}.