Beam Instabilities in the Scale Free Regime

Institute for Complex Systems-CNR, Department of Physics, University Sapienza, Piazzale Aldo Moro 2, 00185 Rome, Italy.
Physical Review Letters (Impact Factor: 7.51). 01/2012; 108(3). DOI: 10.1103/PhysRevLett.108.033901
Source: arXiv


The instabilities arising in a one-dimensional beam sustained by the
diffusive photorefractive nonlinearity in out-of-equilibrium ferroelectrics are
theoretically and numerically investigated. In the "scale-free model", in
striking contrast with the well-known spatial modulational instability, two
different beam instabilities dominate: a defocusing and a fragmenting process.
Both are independent of the beam power and are not associated to any specific
periodic pattern.

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    • "4(g)]; the excited modes coincide, and the dynamics that cause the spectrum to progressively shed off its peaks, show a consistent transfer of spectral content to the lower frequency component. The characteristic frequencies are identified as the first harmonic of the lattice K and the spatial scale introduced by the beam waist [24]. After this phase, the beam begins to modify the local index pattern and its propagation and interesting transient states can emerge; in Fig. 4 "
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