Coupled Complex Ginzburg-Landau Equations Research Articles

Modulated blood waves in the coupled complex Ginzburg–Landau equations of Jeffrey fluids in arteries

Modulated blood waves in the coupled complex Ginzburg–Landau equations of Jeffrey fluids in arteries

Lie symmetry properties of the two-component complex Ginzburg–Landau system with variable coefficients

We classify the Lie point symmetries of a system of nonlinearly coupled complex Ginzburg–Landau equations with time and space dependent potentials and nonlinearities. New families of systems with exact solutions and conservation laws are identified. When there is only space dependence, the system can be reduced to a set of ordinary differential equations for the amplitude and phase components, for which integrability and first integrals are discussed.

Phase Models Beyond Weak Coupling.

We use the theory of isostable reduction to incorporate higher order effects that are lost in the first order phase reduction of coupled oscillators. We apply this theory to weakly coupled complex Ginzburg-Landau equations, a pair of conductance-based neural models, and finally to a short derivation of the Kuramoto-Sivashinsky equations. Numerical and analytical examples illustrate bifurcations occurring in coupled oscillator networks that can cause standard phase-reduction methods to fail.

Manipulation of Gaussian derivative pulses and vector solitons in fiber lasers with analytic modeling by the coupled complex Ginzburg–Landau equations

Both positive- and negative-polarity Gaussian monocycle and doublet pulses, for which the pulse shapes are the first and second derivatives of Gaussian functions plus some continuous-wave backgrounds respectively, are generated in a ring-cavity erbium-doped fiber laser from polarization-locked vector solitons by using passive optical technology. The pulse states are switchable and are found to be the superposition of bright and dark solitons with different widths, amplitudes, time delays, polarizations, and wavelengths. Qualitative analysis of the properties of vector solitons are performed by solving coupled complex Ginzburg–Landau equations, and analytic modeling of the fiber laser is presented. By representing the envelopes of bright soliton by sech- and dark soliton by tanh-based functions, the incoherent superposition of these two soliton components have simulated the experimental observations, and the underlying mechanisms for the formation of monocycle and doublet pulses are attributed to the polarization locking of bright and dark solitons. The theoretical modeling is used to calculate the pulse parameters of the fiber laser, and the intracavity birefringence can be estimated. The results of tunable optical vector solitons are compared with atomic solitons in the system of Bose–Einstein condensation. Since the governing equations for soliton generation in fiber lasers and Bose–Einstein condensation have many properties in common, thus the simulation and propagation of pulsating waves may open a new route to explore the classical solitary dynamics in nonlinear optics and its quantum analogy in ultracold fields.

Amplitude death criteria for coupled complex Ginzburg–Landau systems

Amplitude death, which occurs in a system when one or more macroscopic wavefunctions collapse to zero, has been observed in mutually coupled solid-state lasers, analog circuits, and thermoacoustic oscillators, to name a few applications. While studies have considered amplitude death on oscillator systems and in externally forced complex Ginzburg–Landau systems, a route to amplitude death has not been studied in autonomous continuum systems. We derive simple analytic conditions for the onset of amplitude death of one macroscopic wavefunction in a system of two coupled complex Ginzburg–Landau equations with general nonlinear self- and cross-interaction terms. Our results give a more general theoretical underpinning for recent amplitude death results reported in the literature, and suggest an approach for tuning parameters in such systems so that they either permit or prohibit amplitude death of a wavefunction (depending on the application). Numerical simulation of the coupled complex Ginzburg–Landau equations, for example, including cubic, cubic–quintic, and saturable nonlinearities, is used to illustrate the analytical results.

Analytic homoclinic wave and soliton solutions for 2D coupled complex Ginzburg–Landau equations

Analytic wave solutions including homoclinic wave, kink wave and soliton solutions for the 2D coupled complex Ginzburg–Landau equations are obtained using the auxiliary function method, Hirota method and the ansatz function technique under certain constraint conditions of coefficients in equations, respectively. The result shows that there exists a kink-wave solution which tends to one and the same periodic wave solution as time tends to infinite.

Dissipative Mayer’s waves in fluid-filled viscoelastic tubes

Wave propagation in a viscoelastic tube filled with viscous fluid is addressed. We show that the dissipative Navier–Stokes equations can asymptotically be reduced to a pair of nonlinearly coupled complex Ginzburg–Landau equations. Modulational instability is then investigated analytically and numerically. The instability domain, using the growth rate, is shown to be importantly dependent on the vessel relative stiffness and fluid viscosity. A comprehensive analysis is proposed to that effect, which is confirmed by direct numerical simulations. Dissipative trains of impulses are found as the main manifestation of modulational instability and results are recorded for some hemodynamic factors such as the pressure, velocity and vessel cross-section.

Dynamics of coupled mode solitons in bursting neural networks.

Using an electrically coupled chain of Hindmarsh-Rose neural models, we analytically derived the nonlinearly coupled complex Ginzburg-Landau equations. This is realized by superimposing the lower and upper cutoff modes of wave propagation and by employing the multiple scale expansions in the semidiscrete approximation. We explore the modified Hirota method to analytically obtain the bright-bright pulse soliton solutions of our nonlinearly coupled equations. With these bright solitons as initial conditions of our numerical scheme, and knowing that electrical signals are the basis of information transfer in the nervous system, it is found that prior to collisions at the boundaries of the network, neural information is purely conveyed by bisolitons at lower cutoff mode. After collision, the bisolitons are completely annihilated and neural information is now relayed by the upper cutoff mode via the propagation of plane waves. It is also shown that the linear gain of the system is inextricably linked to the complex physiological mechanisms of ion mobility, since the speeds and spatial profiles of the coupled nerve impulses vary with the gain. A linear stability analysis performed on the coupled system mainly confirms the instability of plane waves in the neural network, with a glaring example of the transition of weak plane waves into a dark soliton and then static kinks. Numerical simulations have confirmed the annihilation phenomenon subsequent to collision in neural systems. They equally showed that the symmetry breaking of the pulse solution of the system leaves in the network static internal modes, sometime referred to as Goldstone modes.

Synchronized nonlinear patterns in electrically coupled Hindmarsh–Rose neural networks with long-range diffusive interactions

Two electrically coupled Hindmarsh–Rose neural networks are considered, each including power-law long-range dispersive interactions. The whole dynamics of the system is reduced to a set of two coupled complex Ginzburg–Landau equations. The linear stability analysis of the plane wave solutions brings about the existence of two dynamical regimes that predict direct and indirect synchronization of the two networks, under the activation of modulational instability. The conditions for the latter to develop are discussed and used to observe numerically the synchronized longtime dynamics of action potentials, under the effect of both long-range intra-coupling and electrical inter-coupling parameters. Mainly, the synchronization criterion depends on the plane wave amplitudes and for some of their values, perfect and partial inter-network synchronization phenomena are observed. It is also found that indirect synchronization between adjacent networks requires local synchronization among neurons of the same fiber. This is discussed based on some further formulation of the synchronization error, additionally to the time series of action potentials. Some spatiotemporal behaviors of the corresponding bursts of spikes are also discussed using coupling parameters.

Similarity of spiral structures between phase and amplitude in coupled complex Ginzburg-Landau equation

Similarity of spiral structures between phase and amplitude in coupled complex Ginzburg-Landau equation

Bright-dark soliton pairs in a self-mode locking fiber laser

We have experimentally observed bright-dark soliton pairs in an erbium-doped fiber ring laser for the first time. This approach is different from the vector dark domain wall solitons which separate the two orthogonal linear polarization eigenstates of the laser emission. In our laser, the bright-dark soliton pairs can co-exist in any one polarization state. Numerical simulations based on the coupled complex Ginzburg-Landau equations have confirmed the experimental results.

Dynamics of Coherent Structures in the Coupled Complex Ginzburg-Landau Equations

Problem statement: In this study, we study the analytical construction of some exact solutions of a system of coupled physical differential equations, namely, the Complex Ginzburg-Landau Equations (CGLEs). CGLEs are intensively studied models of pattern formation in nonlinear dissipative media, with applications to biology, hydrodynamics, nonlinear optics, plasma physics, reaction-diffusion systems and many other fields. Approach: A system of two coupled CGLEs modeling the propagation of pulses under the combined influence of dispersion, self and cross phase modulations, linear and nonlinear gain and loss will be discussed. A Solitary Pulse (SP) is a localized wave form and a front (also termed as shock) refers to a transition connecting two constant, but unequal, asymptotic states. A SP-front pair solution can be analytically obtained by the modified Hirota bilinear method. Results: These wave solutions are deduced by a system of six nonlinear algebraic equations, allowing the amplitudes, wave-numbers, frequency and velocities to be determined. Conclusion: The final exact solution can then be computed by applying the Groebner basis method with a large amount of algebraic simplifications done by the computer software Maple.

Amplitude spiral wave in coupled complex Ginzburg-Landau equation

A novel amplitude spiral wave in coupled complex Ginzburg-Landau equation (CGLE) system is proposed. The stability conditions and the relevant factors are investigated via numerical simulations. On the tip of an amplitude spiral wave there exist no topological defect, which is different from the commonly observed phase spiral wave, and in its amplitude part (instead of phase part) there is a spiral structure. In this research, the stability of amplitude spiral wave is studied by considering the different initial patterns in the case of the system parameter mismatches.

Exact Solutions for Domain Walls in Coupled Complex Ginzburg–Landau Equations

The complex Ginzburg Landau equation (CGLE) is a ubiquitous model for the evolution of slowly varying wave packets in nonlinear dissipative media. A front (shock) is a transient layer between a plane-wave state and a zero background. We report exact solutions for domain walls, i.e., pairs of fronts with opposite polarities, in a system of two coupled CGLEs, which describe transient layers between semi-infinite domains occupied by each component in the absence of the other one. For this purpose, a modified Hirota bilinear operator, first proposed by Bekki and Nozaki, is employed. A novel factorization procedure is applied to reduce the intermediate calculations considerably. The ensuing system of equations for the amplitudes and frequencies is solved by means of computer-assisted algebra. Exact solutions for mutually-locked front pairs of opposite polarities, with one or several free parameters, are thus generated. The signs of the cubic gain/loss, linear amplification/attenuation, and velocity of the coupled-front complex can be adjusted in a variety of configurations. Numerical simulations are performed to study the stability properties of such fronts.

A “Localized Pulse–Moving Front” Pair in a System of Coupled Complex Ginzburg–Landau Equations

A system of nonlinearly coupled complex Ginzburg–Landau equations, CGLEs, serves as a simple model for the dynamics of pulse propagation in dissipative, inhomogeneous media under the combined influence of dispersion, self and cross phase modulations, linear and nonlinear gain or loss. A solitary pulse (SP) is a localized wave form, and a kink or a front refers to a transition connecting two constant, but unequal, asymptotic states. Exact expressions for a “solitary pulse–kink” pair are obtained by a modified Hirota bilinear method. Parameters for these wave configurations are governed by a system of six algebraic equations, allowing the amplitudes, frequencies, and velocities to be determined. Exact solutions for special cases of the dispersive and nonlinear coefficients are obtained by computer algebra software.

Novel type of amplitude spiral wave in a two-layer system

Interaction of spiral waves in a two-layer system described by a model of coupled complex Ginzburg-Landau equations with negative-feedback couplings ε(1) and ε(2) is studied. Synchronization of two spiral waves can be broadly found if ε(1)+ε(2) is sufficiently large. Prior to the synchronization, under the condition of strongly asymmetric coupling (∣ε(1)-ε(2)∣≫0), a novel type of spiral wave, amplitude spiral wave, exists in the driven system. The pattern of amplitude spiral wave shows the spiral in the amplitude and without a singularity point (tip), compared to usual spiral waves known for phase with amplitude uniform far away from tips and rotating around tips.

Synchronization of Two Target Patterns

We have studied the interaction between two target patterns using the coupled complex Ginzburg–Landau equations with two oscillatory modes proposed by Mizuguchi. Two types of synchronizations of oscillation, in- and anti-phase, have been observed. The type of synchronization depends on the distance between the centers of the target patterns. Before synchronization is achieved, the characteristic spatial pattern appears in the other oscillatory mode, which forms a hole at the core of the target. This pattern only depends on the types of synchronization, and we think this mode plays an important role for the synchronization of target patterns.

Dissipative Solitons in Coupled Complex Ginzburg–Landau Equations

Pulse propagation in inhomogeneous nonlinear media with linear and nonlinear gain and loss, described by a system of nonlinearly coupled complex Ginzburg–Landau equations (CGLEs) with variable coefficients, is considered. Exact solitary pulse (SP) solutions are obtained analytically, for special choices of variable coefficients of the nonlinear gain/loss terms, by a modified Hirota bilinear method. The solutions include space- or time-dependent wave numbers, which imply dilatation or compression of the SPs. Stability of the solutions is tested by means of direct simulations, which demonstrate that, in many cases, the SPs are stable against perturbations.

Stability analysis of explosive crystallization front in the ESPE mode

We consider a nonlinear two-dimensional heat conduction model for the dynamics of explosive crystallization (in the ESPE mode) of amorphous films in the case when some thermophysical properties of the amorphous and crystalline phases differ. Conditions for the linear monotonic and oscillatory instabilities of a plane crystallization front are found. For the description of the nonlinear development of the instability, nonlocally coupled complex Ginzburg–Landau equations for the amplitudes of the unstable modes, which involve averaged terms, are derived. The plane wave solutions of the amplitude equations are found, and the regions of stability for these solutions are determined.

Modulational instability in a purely nonlinear coupled complex Ginzburg–Landau equations through a nonlinear discrete transmission line

We study wave propagation in a nonlinear transmission line with dissipative elements. We show analytically that the telegraphers' equations of the electrical transmission line can be modeled by a pair of continuous coupled complex Ginzburg-Landau equations, coupled by purely nonlinear terms. Based on this system, we investigated both analytically and numerically the modulational instability (MI). We produce characteristics of the MI in the form of typical dependence of the instability growth rate on the wavenumbers and system parameters. Generic outcomes of the nonlinear development of the MI are investigated by dint of direct simulations of the underlying equations. We find that the initial modulated plane wave disintegrates into waves train. An apparently turbulent state takes place in the system during the propagation.