Gray and dark spatial solitary waves in slab waveguides

The possibility of the stationary propagation of light waves in a thin linear film bounded by a self-defocusing nonlinear medium is examined. Both gray and dark solitary waves are found to be possible trapped-mode patterns, in addition to a series of trapped dark oscillatory wave patterns. This contrasts with a uniform self-defocusing medium, in which self-guidance can occur only for dark spatial solitary waves.