Phys. Rev. E 73, 036614 (2006) [10 pages]Nonlocal description of X waves in quadratic nonlinear materialsReceived 23 December 2005; published 22 March 2006 We study localized light bullets and X waves in quadratic media and show how the notion of nonlocality can provide an alternative simple physical picture of both types of multidimensional nonlinear waves. For X waves we show that a local cascading limit in terms of a nonlinear Schrödinger equation does not exist—one needs to use the nonlocal description, because the nonlocal response function does not converge toward a δ function. Also, we use the nonlocal theory to show that the coupling to the second harmonic is able to generate an X shape in the fundamental field despite having anomalous dispersion, in contrast to the predictions of the cascading limit. © 2006 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevE.73.036614
DOI:
10.1103/PhysRevE.73.036614
PACS:
03.50.De, 05.45.Yv, 42.65.Jx, 42.65.Tg
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