Temporal fluctuations of waves in weakly nonlinear disordered media
arXiv:cond-mat/0101059 · doi:10.1103/PhysRevE.63.056614
Abstract
We consider the multiple scattering of a scalar wave in a disordered medium with a weak nonlinearity of Kerr type. The perturbation theory, developed to calculate the temporal autocorrelation function of scattered wave, fails at short correlation times. A self-consistent calculation shows that for nonlinearities exceeding a certain threshold value, the multiple-scattering speckle pattern becomes unstable and exhibits spontaneous fluctuations even in the absence of scatterer motion. The instability is due to a distributed feedback in the system "coherent wave + nonlinear disordered medium". The feedback is provided by the multiple scattering. The development of instability is independent of the sign of nonlinearity.
RevTeX, 15 pages (including 5 figures), accepted for publication in Phys. Rev. E
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