Search results for "Pattern formation"
showing 10 items of 408 documents
Incoherent Soliton Turbulence in Nonlocal Nonlinear Media
2011
The long-term behavior of a modulationally unstable nonintegrable system is known to be characterized by the soliton turbulence self-organization process: It is thermodynamically advantageous for the system to generate a large-scale coherent soliton in order to reach the (‘‘most disordered’’) equilibrium state. We show that this universal process of self-organization breaks down in the presence of a highly nonlocal nonlinear response. A wave turbulence approach based on a Vlasov-like kinetic equation reveals the existence of an incoherent soliton turbulence process: It is advantageous for the system to self-organize into a large-scale, spatially localized, incoherent soliton structure.
Efficient control of the energy exchange due to the Manakov vector-soliton collision
2003
By examining the concept of energy exchange among the orthogonally polarized components of each of two colliding (Manakov-like) vector solitons it is observed that a maximum or an efficient energy-exchange process is possible only for an appropriate choice of the initial physical parameters (namely, frequency separation, polarizations, time delay, and pulse-width separation between the colliding solitons) for which L(W) (walk-off length) >>L(NL) (nonlinear length). However, in this case only, the amount of energy-exchange can be considerably increased or decreased by appropriately changing the phases of colliding solitons without altering the walk-off length and the initial energy distribut…
A Look at Some Remarkable Mathematical Techniques
1996
The nonlinear equations that we have encountered in the previous chapters can be solved by using mathematical techniques such as the powerful inverse scattering transform (IST) (Gardner et al. 1967) and the remarkable Hirota method (Hirota 1971). Specifically, in addition to the one-soliton solutions, explicit multisoliton solutions representing the interaction of any number of solitons can be constructed. Moreover, in several cases a precise prediction, closely related to experiments, can be made by the IST of the nonlinear response of the physical system, that is, of the number of solitons that can emerge from a finite initial disturbance (Zakharov, 1980. Ablowitz and Segur 1981; Calogero…
Nonlocality and fluctuations near the optical analog of a sonic horizon
2013
We consider the behavior of fluctuations near the sonic horizon and the role of the nonlocality of interaction (nonlinearity) on their regularization. The nonlocality dominates if its characteristic length scale is larger than the regularization length. The influence of nonlocality may be important in the current experiments on the transonic flow in Kerr nonlinear media. Experimental conditions, under which the observation of straddled fluctuations can be observed, are discussed.
Transverse patterns in degenerate optical parametric oscillation and degenerate four-wave mixing.
1996
Transverse pattern formation in both degenerate optical parametric oscillation and degenerate four-wave mixing is considered both theoretically and numerically. In the limit of small signal detuning both systems are shown to be described by the real Swift-Hohenberg equation. Contrarily, for small signal and large pump detunings the Swift-Hohenberg equation is modified differently in both systems, by the appearance of additional nonlinear terms, which signal the existence of nonlinear resonances that are theoretically studied through the derivation of the amplitude equation for the roll pattern in both systems. Numerical analysis supports the theoretical predictions. \textcopyright{} 1996 Th…
Discrete-ring vortex solitons
2010
We study analytically and numerically the existence and stability of discrete vortex solitons in the circular arrays of nonlinear optical waveguides, governed by the discrete nonlinear Schrodinger equation. Stable vortex breathers with periodically oscillating topological charge are identified and a continuous interpolating map is constructed which allows to recover trajectories of individual phase dislocations in the form of hyperbolic avoided crossings.
Long-Range interaction of temporal incoherent solitons
2014
Contrary to conventional solitons, temporal incoherent solitons are sustained by a defocusing nonlinearity with anomalous dispersion and exhibit a non-mutual attractive-repulsive interaction. We explain these results by a long-range Vlasov formalism.
Breather compactons in nonlinear Klein-Gordon systems
1999
We demonstrate the existence of a localized breathing mode with a compact support, i.e., a stationary breather compacton, in a nonlinear Klein-Gordon system. This breather compacton results from a delicate balance between the harmonicity of the substrate potential and the total nonlinearity induced by the substrate potential and the coupling forces between adjacent lattice sites.
Solitons in Nonlinear Transmission Lines
1996
Although solitary waves and solitons were originally discovered in the context of water waves and lattice dynamics, consideration of these physical systems (which will be considered in Chaps.5 and 8) leads to calculations far too involved for pedagogical purposes. Thus, for an introduction to the soliton concept, we therefore consider simple wave propagation in electrical nonlinear transmission lines and electrical networks.
On the correlation between phase-locking modes and Vibrational Resonance in a neuronal model
2018
International audience; We numerically and experimentally investigate the underlying mechanism leading to multiple resonances in the FitzHugh-Nagumo model driven by a bichromatic excitation. Using a FitzHugh-Nagumo circuit, we first analyze the number of spikes triggered by the system in response to a single sinusoidal wave forcing. We build an encoding diagram where different phase-locking modes are identified according to the amplitude and frequency of the sinusoidal excitation. Next, we consider the bichromatic driving which consists in a low frequency sinusoidal wave perturbed by an additive high frequency signal. Beside the classical Vibrational Resonance phenomenon, we show in real ex…