SMALL-STENCIL PADE SCHEMES TO SOLVE NONLINEAR EVOLUTION EQUATIONS

A set of small-stencil new Pade schemes with the same denominator are presented to solve high-order nonlinear evolution equations. Using this scheme, the fourth-order precision can not only be kept, but also the final three-diagonal discrete systems are solved by simple Doolittle methods, or ODE systems by Runge-Kutta technique. Numerical samples show that the schemes are very satisfactory. And the advantage of the schemes is very clear compared to other finite difference schemes.     

The first-order perturbed SBS equations

Summary Using standard multiscale techniques, a first-order perturbation theory for SBS is developed. In the presence of small damping, we find that there is a stationary solution for a soliton which is a fixed point. The velocity of this soliton is determined by the damping coefficients. In addition, there is also a constant shift in the pump intensity in the region between the front of the backward moving soliton and the forward light cone of the pump.     

Soliton Resonances for the MKP-II

Using the second flow (derivative reaction-diffusion system) and the third one of the dissipative SL(2, ℝ) Kaup-Newell hierarchy, we show that the product of two functions satisfying those systems is a solution of the modified Kadomtsev-Petviashvili equation in 2+1 dimensions with negative dispersion (MKP-II). We construct Hirota’s bilinear representations for both flows and combine them as the bilinear system for the MKP-II. Using this bilinear form, we find one- and two-soliton solutions for the MKP-II. For special values of the parameters, our solution shows resonance behavior with the creation of four virtual solitons. Our approach allows interpreting the resonance soliton as a composite object of two dissipative solitons in 1+1 dimensions.__________Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 144, No. 1, pp. 133–142, July, 2005.     

Simulations of rare events in fiber optics by interacting particle systems

In this paper we study the robustness of linear pulses, solitons, and dispersion-managed solitons, under the influence of random perturbations. First, we address the problem of the estimation of the outage probability due to polarization-mode dispersion. Second, we compare the pulse broadening due to random fluctuations of the group-velocity dispersion. We use an original interacting particle system to estimate the tails of the probability density functions of the pulse widths. A new adaptative Monte Carlo method is applied that enforces the simulations to probe the regions of practical importance by selection and mutation steps.     

Spatial Dark Solitons in an Atom Laser Beam

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B(a)cklund Transformation and Multiple Soliton Solutions for (3+1)-Dimensional Potential-YTSF Equation

We study an approach to constructing multiple soliton solutions of the (3 1)-dimensional nonlinear evolu tion equation. We take the (3 1)-dimensional potential-YTSF equation as an example. Using the extended homogeneous balance method, one can find a Backlund transformation to decompose the (3 1)-dimensional potential-YTSF equa tion into a set of partial differential equations. Starting from these partial differential equations, some multiple soliton solutions for the (3 1)-dimensional potential-YTSF equation are obtained by introducing a class of formal solutions.     

Soliton Solutions of DNLS Equation Found by IST Anew and its Verification in Marchenko Formalism

A general procedure is proposed to derive the multi-soliton solutions of DNLS equation with vanishing boundary value, and the two-soliton solutions of it is given as an example. Furthermore, the verification of multi-soliton solutions is done through Marchenko formalism. PACS numbers: 05.45.Yv; 02.30.-f; 11.10.Ef     

The modified propagation equation for TM polarized subwavelength spatial solitons in a nonlinear planar waveguide

The wave equation of TM polarized subwavelength beam propagations in a nonlinear planar waveguide is derived beyond the paraxial approximation. This modified equation contains more higher-order linear and nonlinear terms than the nonlinear Schrödinger equation. The propagation of fundamental subwavelength spatial solitons is numerically studied. It is shown that the effect of the higher nonlinear terms is significant. That is, for the propagation of narrower beam the modified nonlinear Schrödinger equation is more suitable than the nonlinear Schrödinger equation.     

On timing Jitter in wavelength-division multiplexed soliton systems

Collision-induced timing shifts in a wavelength-division multiplexed soliton system are computed when damping, amplification, filtering and positive dispersion management following the loss profile are included. A statistical analysis is presented which takes into account the resulting effect of the large number of collisions occurring in the fiber. Analytic expressions are derived for the root mean square timing jitter and the maximum length of error-free transmission with an arbitrary number of channels. An extensive analysis of system performance corresponding to situations with and without filters and/or dispersion management is carried out.     

量子孤子在光纤中的传播特性

利用线性近似和分步傅里叶变换法，分析了量子孤子在无耗光纤中的传播规律.量子孤子在光纤中的行为由量子非线性薛定谔方程（QNSE）描述,用线性近似法求解此方程，将量子噪声与经典部分分离，着重讨论了孤子量子噪声的演化行为，分析了高阶色散对噪声压缩的影响.结果表明：在较短的传输距离内，孤子的压缩性依然存在，但无论初始时压缩参数如何，随着传输距离的增加，压缩比会达到一个极限;在负色散区，三阶色散对压缩效应无影响.