Asymptotical solutions of coupled nonlinear Schrodinger equations with perturbations

In this paper Lou＇s direct perturbation method is applied to the perturbed coupled nonlinear Schrodinger equations to obtain their asymptotical solutions, which include not only the zero-order solutions but also the first-order modifications. Based on the asymptotical solutions, the effects of perturbations on soliton parameters and the collision between two solitons are then discussed in brief. Furthermore, we directly simulate the perturbed coupled nonlinear SchrSdinger equations by split-step Fourier method to check the validity of the direct perturbation method. It turns out that our analytical results are well supported by the numerical calculations.

Dynamics of optical rogue waves in inhomogeneous nonlinear waveguides

We propose a unified theory to construct exact rogue wave solutions of the （2＋1）-dimensional nonlinear Schr6dinger equation with varying coefficients. And then the dynamics of the first- and the second-order optical rogues are investigated. Finally, the controllability of the optical rogue propagating in inhomogeneous nonlinear waveguides is discussed. By properly choosing the distributed coefficients, we demonstrate analytically that rogue waves can be restrained or even be annihilated, or emerge periodically and sustain forever. We also figure out the center-of-mass motion of the rogue waves.

Approximate Solutions of Perturbed Nonlinear Schroedinger Equations

By applying Lou＇s direct perturbation method to perturbed nonlinear Schroedinger equation and the critical nonlinear SchrSdinger equation with a small dispersion, their approximate analytical solutions including the zero-order and the first-order solutions are obtained. Based on these approximate solutions, the analytical forms of parameters of solitons are expressed and the effects of perturbations on solitons are briefly analyzed at the same time. In addition, the perturbed nonlinear Schroedinger equations is directly simulated by split-step Fourier method to check the validity of the direct perturbation method. It turns out that the analytical results given by the direct perturbation method are well supported by numerical calculations.

Exotic Localized Coherent Structures of New (2+1)-Dimensional Soliton Equation

The variable separation approach is used to obtain localized coherent structures of the new (2+1)-dimensional nonlinear partialdifferential equation. Applying the Backlund transformation and introducing the arbitraryfunctions of the seed solutions, the abundance of the localized structures of this model are derived. Some special types ofsolutions solitoff, dromions, dromion lattice, breathers and instantons are discussed by selecting the arbitrary functionsappropriately. The breathers may breath in their amplititudes, shapes, distances among the peaks and even the numberof the peaks.

Abundant Multisoliton Structures of the Generalized Nizhnik-Novikov-Veselov Equation

Using the extended homogenous balance method, we obtainabundant exact solution structures ofa (2+1)dimensional integrable model, the generalized Nizhnik-Novikov-Veselov equation. By means of the leading order termanalysis, the nonlinear transformations of generalized Nizhnik-Novikov-Veselov equation are given first, and then somespecial types of single solitary wave solution and the multisoliton solutions are constructed.

Multiple Soliton Solutions of the Dispersive Long-Wave Equations

Using a simple homogeneous balance method,which is very concise and primary,we find the multiple soliton solutions of the dispersive long-wave equations.The method can be generalized to deal with the higher dimensional dispersive long-wave equations and other class of nonlinear equation.

Dynamic stability and manipulation of bright matter-wave solitons by optical lattices in Bose-Einstein condensates

An extended variation approach to describing the dynamic evolution of self-attractive Bose-Einstein condensates is developed. We consider bright matter-wave solitons in the presence of a parabolic magnetic potential and a timespace periodic optical lattice. The dynamics of condensates is shown to be well approximated by four coupled nonlinear differential equations. A noteworthy feature is that the extended variation approach gives a critical strength ratio to support multiple stable lattice sites for the condensate. We further examine the existence of the solitons and their stabilities at the multiple stable lattice sites. In this case, the analytical predictions of Bose-Einstein condensates variational dynamics are found to be in good agreement with numerical simulations. We then find a stable region for successful manipulating matter-wave solitons without collapse, which are dragged from an initial stationary to a prescribed position by a moving periodic optical lattice.

Solitary Wave Solutions of Discrete Complex Ginzburg-Landau Equation by Modified Adomian Decomposition Method

In this paper, exact and numerical solutions are calculated for discrete complex Ginzburg-Landau equation with initial condition by considering the modified Adomian decomposition method （mADM）, which is an efficient method and does not need linearization, weak nonlinearity assumptions or perturbation theory. The numerical solutions are also compared with their corresponding analytical solutions. It is shown that a very good approximation is achieved with the analytical solutions. Finally, the modulational instability is investigated and the corresponding condition is given.

Vortical Solitons of Three-Dimensional Bose-Einstein Condensates under Both a Bichromatic Optical Lattice and Anharmonic Potentials

We study Bose–Einstein condensate vortical solitons under both a bichromatic optical lattice and anharmonic potential.The vortical solitons are built in the form of a layer-chain structure made up of two fundamental vortices along the bichromatic optical lattice direction,which have not been reported before in the three-dimensional Bose–Einstein condensate.A variation approach is applied to find the optimum initial solutions of vortical solitons.The stabilities of the vortical solitons are confirmed by the numerical simulation of the time-dependent Gross–Pitaevskii equation.In particular,stable Bose–Einstein condensate vortical solitons with fundamental vortices of different atomic numbers in the external potential within a range of experimentally achievable timescales are found.We further manipulate the vortical solitons to an arbitrary position by steadily moving the bichromatic optical lattice,and find a stable region for the successful manipulation of vortical solitons without collapse.These results provide insight into controlling and manipulating the Bose–Einstein condensate vortical solitons for macroscopic quantum applications.

Symmetries of the Variable Coefficient KdV Equation and Three Hierarchies of the Integrodifferential Variable Coefficient KdV Equation

By using a simple method to factorize the recursion operator,the inverse recursion operator of the variable coefficient KdV cquqtion is exhibited explicitly.Thee new sets of symmetries of the variable coefficient KdV equation arc given in addition to the known K symmetries andτsymmetries.Starting from these three sets of symmetries,we obtained three hierarchies of the variable coefficient KdV integro-differential equations.

A New Class of Periodic Solutions to （2＋1）-Dimensional KdV Equations

We investigate a new class of periodic solutions to (2+1)-dimensional KdV equations, by both the linear superposition approach and the mapping deformation method. These new periodic solutions are suitable combinations of the periodic solutions to the (2+1)-dimensional KdV equations obtained by means of the Jacobian elliptic function method, but they possess different periods and velocities.

Multisoliton Solutions of the (2+1)-Dimensional KdV Equation

Using the extension homogeneous balance method,we have obtained some new special types of soliton solutions of the (2+1)-dimensional KdV equation.Starting from the homogeneous balance method,one can obtain a nonlinear transformation to simple (2+1)-dimensional KdV equation into a linear partial differential equation and two bilinear partial differential equations.Usually,one can obtain only a kind of soliton-like solutions.In this letter,we find further some special types of the multisoliton solutions from the linear and bilinear partial differential equations.

Modulational Instability of （1 ＋ 1）-Dimensional Bose-Einstein Condensate with Three-Body Interatomic Interaction

The modulational instability of Bose-Einstein condensate with three-body interatomic interaction and external harmonic trapping potential is investigated. Both of our analytical and numerical results show that the external potential will either cause the excitation of modulationally unstable modes or restrain the modulationally unstable modes from growing.

Controlled Manipulation with a Bose-Einstein Condensates N-Soliton Train under the Influence of Harmonic and Tilted Periodic Potentials

A model of the perturbed complex Toda chain （PCTC） to describe the dynamics of a Bose-Einstein condensate （BEC） N-soliton train trapped in an applied combined external potential consisting of both a weak harmonic and tilted periodic component is first developed. Using the developed theory, the BEC N-soliton train dynamics is shown to be well approximated by 4N coupled nonlinear differential equations, which describe the fundamental interactions in the system arising from the interplay of amplitude, velocity, centre-of-mass position, and phase. The simplified analytic theory allows for an efficient and convenient method for characterizing the BEC N-soliton train behaviour. It further gives the critical values of the strength of the potential for which one or more localized states can be extracted from a soliton train and demonstrates that the BEC N-soliton train can move selectively from one lattice site to another by simply manipulating the strength of the potential.

Soliton and Periodic Travelling Wave Solutions for Quadratic Nonlinear Media

Many sets of the soliton and periodic travelling wave solutions for the quadratic χ^（2） nonlinear system are obtained by the Backlund transformation and the trial method. The property of the propagation for some travelling waves is investigated.

Solutions to the equations describing materials with competing quadratic and cubic nonlinearities

The Lie group theoretical method is used to study the equations describing materials with competing quadratic and cubic nonlinearities. The equations shave some of the nice properties of soliton equations. From the elliptic functions expansion method, we obtain large families of analytical solutions, in special cases, we have the periodic, kink and solitary solutions of the equations. Furthermore, we investigate the stability of these solutions under the perturbation of amplitude noises by numerical simulation.

Variable-Coefficient Mapping Method Based on Elliptical Equation and Exact Solutions to Nonlinear SchrSdinger Equations with Variable Coefficient

In this paper, by means of the variable-coefficient mapping method based on elliptical equation, we obtain explicit solutions of nonlinear Schrodinger equation with variable-coefficient. These solutions include Jacobian elliptic function solutions, solitary wave solutions, soliton-like solutions, and trigonometric function solutions, among which some are found for the first time. Six figures are given to illustrate some features of these solutions. The method can be applied to other nonlinear evolution equations in mathematical physics.

Generation and Control of Shock Waves in Exciton-Polariton Condensates

We propose a scheme to generate and control supersonic shock waves in a non-resonantly incoherent pumped exciton-polariton condensate,and different types of shock waves can be generated.Under conditions of different initial step waves,the ranges of parameters about various shock waves are determined by the initial incidence function and the cross-interaction between the polariton condensate and the reservoir.In addition,shock waves are successfully found by regulating the incoherent pump.In the case of low condensation rate from polariton to condensate,these results are similar to the classical nonlinear Schr¨odinger equation,and the effect of saturated nonlinearity resulted from cross interaction is equivalent to the self-interaction between polariton condensates.At high condensation rates,profiles of shock waves become symmetrical due to the saturated nonlinearity.Compared to the previous studies in which the shock wave can only be found in the system with repulsive self-interaction(defocusing nonlinearity),we not only discuss the shock wave in the exciton-polariton condensate system with the repulsive self-interaction,but also find the shock wave in the condensates system with attractive self-interaction.Our proposal may provide a simple way to generate and control shock waves in non-resonantly pumped excitonpolariton systems.

Explicit Soliton and Periodic Solutions to Three-Wave System with Quadratic and Cubic Nonlinearities

Lie group theoretical method and the equation of the Jacobi elliptic function are used to study the three wave system that couples two fundamental frequency （FF） and a single second harmonic （SH） one by competing X^（2） （quadratic） and X^（3） （cubic） nonlinearities and birefringence. This system shares some of the nice properties of soliton system. On the phase-locked condition; we obtain large families of analytical solutions as the soliton, kink and periodic solutions of this system.

Perturbative Painlevé Analysis of General KdV System and Its Exact Soliton Solutions

Using the standard Painlevé analysis and the perturbative method, the Painlevé test for the logarithmic branch is investigated. Nine arbitrary functions are obtained and the Baecklund transformation of the logarithmic branch is given. Using the new type Baecklund transformation, many exact solutions are obtained.