Coupled Complex Ginzburg-Landau Research Articles

Non-Lagrangian approach for coupled complex Ginzburg-Landau systems with higher order-dispersion

It is known that after a particular distance of evolution in fiber lasers, two (input) asymmetric soliton like pulses emerge as two (output) symmetric pulses having same and constant energy. We report such a compensation technique in dispersion managed fiber lasers by means of a semi-analytical method known as collective variable approach (CVA) with including third-order dispersion (TOD). The minimum length of fiber laser, at which the output symmetric pulses are obtained from the input asymmetric ones, is calculated for each and every pulse parameters numerically by employing Runge-Kutta fourth order method. The impacts of intercore linear coupling, asymmetric nature of initial parameters and TOD on the evolution of pulse parameters and on the minimum length are also investigated. It is found that strong intercore linear coupling and asymmetric nature of input pulse parameters result in the reduction of fiber laser length. Also, the role of TOD tends to increase the width of the pulses as well as their energies. Besides, chaotic patterns and bifurcation points on the minimum length of the fiber owing to the impact of TOD are also reported in a nutshell.

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.

Collective dynamics of globally delay-coupled complex Ginzburg-Landau oscillators.

The effect of time-delayed coupling on the collective behavior of a population of globally coupled complex Ginzburg-Landau oscillators is investigated. A detailed numerical study is carried out to study the impact of time delay on various collective states that include synchronous states, multicluster states, chaos, amplitude-mediated chimeras, and incoherent states. It is found that time delay can bring about significant changes in the dynamical properties of these states including their regions of existence and stability. In general, an increase in time delay is seen to lower the threshold value of the coupling strength for the occurrence of such states and to shift the existence domain toward more negative values of the linear dispersion parameter. Further insights into the numerical findings are provided, wherever possible, by exact equilibrium and stability analysis of these states in the presence of time delay.

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.

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

Anticipated synchronization in coupled complex Ginzburg-Landau systems.

We study the occurrence of anticipated synchronization in two complex Ginzburg-Landau systems coupled in a master-slave configuration. Master and slave systems are ruled by the same autonomous function, but the slave system receives the injection from the master and is subject to a negative delayed self-feedback loop. We give evidence that the magnitude of the largest anticipation time, obtained for complex-valued coupling constants, depends on the dynamical regime where the system operates (defect turbulence, phase turbulence, or bichaos) and scales with the linear autocorrelation time of the system. We also provide analytical conditions for the stability of the anticipated synchronization manifold that are in qualitative agreement with those obtained numerically. Finally, we report on the existence of anticipated synchronization in coupled two-dimensional complex Ginzburg-Landau systems.

Chimera states: the existence criteria revisited.

Chimera states, representing a spontaneous breakup of a population of identical oscillators that are identically coupled, into subpopulations displaying synchronized and desynchronized behavior, have traditionally been found to exist in weakly coupled systems and with some form of nonlocal coupling between the oscillators. Here we show that neither the weak-coupling approximation nor nonlocal coupling are essential conditions for their existence. We obtain, for the first time, amplitude-mediated chimera states in a system of globally coupled complex Ginzburg-Landau oscillators. We delineate the dynamical origins for the formation of such states from a bifurcation analysis of a reduced model equation and also discuss the practical implications of our discovery of this broader class of chimera states.

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.

Bounded Solutions of Nonlocal Complex Ginzburg–Landau Equations for a Subcritical Bifurcation

Stable periodic solutions of a system of two nonlocal coupled complex Ginzburg–Landau (CGL) equations describing the dynamics of a subcritical Hopf bifurcation in a spatially extended system are found analytically in the limit of large dispersion coefficients. The domains in the parameter space where these solutions exist and are stable are determined. It is shown that the existence and stability depend on the sign of the coupling parameter and on the ratio of the dispersion coefficients. Numerical simulations of the system of nonlocal coupled CGL equations confirm the analytical results and exhibit other bounded dynamic regimes, such as standing waves and spatio-temporal chaos.

Solitary pulses in linearly coupled Ginzburg-Landau equations

This article presents a brief review of dynamical models based on systems of linearly coupled complex Ginzburg-Landau (CGL) equations. In the simplest case, the system features linear gain, cubic nonlinearity (possibly combined with cubic loss), and group-velocity dispersion (GVD) in one equation, while the other equation is linear, featuring only intrinsic linear loss. The system models a dual-core fiber laser, with a parallel-coupled active core and an additional stabilizing passive (lossy) one. The model gives rise to exact analytical solutions for stationary solitary pulses (SPs). The article presents basic results concerning stability of the SPs; interactions between pulses are also considered, as are dark solitons (holes). In the case of the anomalous GVD, an unstable stationary SP may transform itself, via the Hopf bifurcation, into a stable localized breather. Various generalizations of the basic system are briefly reviewed too, including a model with quadratic (second-harmonic-generating) nonlinearity and a recently introduced model of a different but related type, based on linearly coupled CGL equations with cubic-quintic nonlinearity. The latter system features spontaneous symmetry breaking of stationary SPs, and also the formation of stable breathers.

Chimera Ising walls in forced nonlocally coupled oscillators

Nonlocally coupled oscillator systems can exhibit an exotic spatiotemporal structure called a chimera, where the system splits into two groups of oscillators with sharp boundaries, one of which is phase locked and the other phase randomized. Two examples of chimera states are known: the first one appears in a ring of phase oscillators, and the second is associated with two-dimensional rotating spiral waves. In this paper, we report yet another example of the chimera state that is associated with the so-called Ising walls in one-dimensional spatially extended systems. This chimera state is exhibited by a nonlocally coupled complex Ginzburg-Landau equation with external forcing.

Quantitative and qualitative characterization of zigzag spatiotemporal chaos in a system of amplitude equations for nematic electroconvection

It has been suggested by experimentalists that a weakly nonlinear analysis of the recently introduced equations of motion for the nematic electroconvection by M. Treiber and L. Kramer [Phys. Rev. E 58, 1973 (1998)] has the potential to reproduce the dynamics of the zigzag-type extended spatiotemporal chaos and localized solutions observed near onset in experiments [M. Dennin, D. S. Cannell, and G. Ahlers, Phys. Rev. E 57, 638 (1998); J. T. Gleeson (private communication)]. In this paper, we study a complex spatiotemporal pattern, identified as spatiotemporal chaos, that bifurcates at the onset from a spatially uniform solution of a system of globally coupled complex Ginzburg-Landau equations governing the weakly nonlinear evolution of four traveling wave envelopes. The Ginzburg-Landau system can be derived directly from the weak electrolyte model for electroconvection in nematic liquid crystals when the primary instability is a Hopf bifurcation to oblique traveling rolls. The chaotic nature of the pattern and the resemblance to the observed experimental spatiotemporal chaos in the electroconvection of nematic liquid crystals are confirmed through a combination of techniques including the Karhunen-Loeve decomposition, time-series analysis of the amplitudes of the dominant modes, statistical descriptions, and normal form theory, showing good agreement between theory and experiments.

Localized states in a triangular set of linearly coupled complex Ginzburg-Landau equations

We introduce a pattern-formation model based on a symmetric system of three linearly coupled cubic-quintic complex Ginzburg-Landau equations, which form a triangular configuration. This is the simplest model of a multicore fiber laser. We identify stability regions for various types of localized patterns possible in this setting, which include stationary and breathing triangular vortices.

Amplitude modulation and relaxation-oscillation of counterpropagating rolls within a broken-symmetry laser-induced electroconvection strip

We report a liquid-crystal pattern-formation experiment in which we break the lateral (translational) symmetry of a nematic medium with a laser-induced thermal gradient. The work is motivated by an improved measurement (reported here) of the temperature dependence of the electroconvection threshold voltage in planar-nematic 4-methoxybenzylidene-4-butylaniline. In contrast with other broken-symmetry-pattern studies that report a uniform drift, we observe a strip of counterpropagating rolls that collide at a sink point, and a strong temporally periodic amplitude modulation within a width of 3-4 rolls about the sink point. The time dependence of the amplitude at a fixed position is periodic but displays a nonsinusoidal relaxation-oscillation profile. After reporting experimental results based on spacetime contours and wave number profiles, along with a measurement of the change in the drift frequency with applied voltage at a fixed control parameter, we propose some potential guidelines for a theoretical model based on saddle-point solutions for Eckhaus-unstable states and coupled complex Ginzburg-Landau equations.

Chaotic dynamics of a passively mode-locked soliton fiber ring laser

We report on the experimental and numerical studies of the chaotic dynamics of a soliton fiber ring laser passively mode-locked by using the nonlinear polarization rotation (NPR) technique. Period-doubling route to chaos on the soliton repetition rate of either the single pulse soliton or the bound solitons of the laser was experimentally observed. Based on a coupled complex Ginzburg-Landau equation model and also taking into account the laser cavity effect, we further show numerically that the period-doubling bifurcations and route to chaos are intrinsic properties of the laser, whose appearance is independent of the details of the laser cavity design and the laser soliton operation. Property of the solitons under the dynamical bifurcations is also numerically investigated.

Solitary pulses in linearly coupled cubic–quintic Ginzburg–Landau equations

A dynamical model based on a symmetric system of linearly coupled complex Ginzburg–Landau (CGL) equations is introduced, with cubic–quintic (CQ) nonlinearities in the dissipative and conservative parts of the equations. In nonlinear optics, the system models a twin-core fiber laser. We focus on the study of spontaneous symmetry breaking in solitary pulses (SPs). For this purpose, direct simulations are used, aiming to reach stable SP states as attractors of the system. Different initial conditions lead to a set of established states, including symmetric and asymmetric stationary SPs, split pulses (ones with separated centers of the two components), and breathers (oscillating SPs which feature long-period beatings). Two diagrams of the stable states are constructed, starting from initial conditions of two different types. The system demonstrates hysteresis, which chiefly includes bistability, and in some cases tristability.

Controlling Chaos with Rectificative Feedback Injections in 2D Coupled Complex Ginzburg-Landau Oscillators**The project supported in part by National Natural Science Foundation of China (Nos. 10175009 and 19805002), the Special Funds for Major State Basic Research Projects (No. G2000077304), the Foundation for University Key Teacher by the MOE (No. GG-140-87501-1370), the Foundation for the Author of National Excellent Doctoral Dissertation of

A model of two-dimensional coupled complex Ginzburg-Landau oscillators driven by a rectificative feedback controller is used to study controlling spatiotemporal chaos without gradient force items. By properly selecting the signal injecting position with considering the maximum gap between signals and targets, and adjusting the control time interval, we have finally obtained the efficient chaos control via numerical simulations.

Synchronization of Spatiotemporal Chaos in Coupled Complex Ginzburg-Landau Oscillators**The project supported by National Natural Science Foundation of China, the Special Funds for Major State Basic Research Projects (G2000077304), the Huo Yingdong Foundation for Excellent Young Teachers, the Foundation for Excellent Doctoral Dissertation and the Foundation for University Key Teacher by the Ministry of Education of China

Synchronization of spatiotemporal distributed system is investigated by considering the model of 1D diffusively coupled complex Ginzburg–Landau oscillators. An itinerant approach is suggested to randomly move turbulent signal injections in the space of spatiotemporal chaos. Our numerical simulations show that perfect turbulence synchronization can be achieved with properly selected itinerant time and coupling intensity.