@ARTICLE\{IMM2001-0162,
    author       = "W. Krolikowski and O. Bang and J. J. Rasmussen and J. Wyller",
    title        = "Modulational instability in nonlocal nonlinear Kerr media",
    year         = "2001",
    month        = "jul",
    pages        = "1-8/016612",
    journal      = "Physical Review E",
    volume       = "64",
    editor       = "",
    number       = "1",
    publisher    = "",
    url          = "http://www2.compute.dtu.dk/pubdb/pubs/162-full.html",
    abstract     = "We study modulational instability (MI) of plane waves in nonlocal nonlinear Kerr media. For a focusing nonlinearity we show that, although the nonlocality tends to suppress {MI,} it can never remove it completely, irrespective of the particular profile of the nonlocal response function. For a defocusing nonlinearity the stability properties depend sensitively on the response function profile: for a smooth profile (e.g., a Gaussian) plane waves are always stable, but {MI} may occur for a rectangular response. We also find that the reduced model for a weak nonlocality predicts {MI} in defocusing media for arbitrary response profiles, as long as the intensity exceeds a certain critical value. However, it appears that this regime of {MI} is beyond the validity of the reduced model, if it is to represent the weakly nonlocal limit of a general nonlocal nonlinearity, as in optics and the theory of Bose-Einstein condensates."
}