Manakov solitons and polarization mode dispersion

The effect of polarization mode dispersion (PMD) on Manakov solitons and dispersion managed solitons is treated analytically and by numerical simulation. In the analytic approach the internal motion of the Manakov soliton is represented as a damped harmonic oscillator. The PMD functions as a white noise source driving the oscillations. It is shown that the solitons can withstand PMD up to a certain instability threshold for which an analytic expression is obtained. This threshold is also evaluated for dispersion managed solitons. (c) 2000 American Institute of Physics.     

Nonautonomous solitons in external potentials

Novel soliton solutions for the nonautonomous nonlinear Schr?dinger equation models with linear and harmonic oscillator potentials substantially extend the concept of classical solitons and generalize it to the plethora of nonautonomous solitons that interact elastically and generally move with varying amplitudes, speeds, and spectra adapted both to the external potentials and to the dispersion and nonlinearity variations. The nonautonomous soliton concept can be applied to different physical systems, from hydrodynamics and plasma physics to nonlinear optics and matter waves, and offer many opportunities for further scientific studies.     

Optical Solitons in Fibers for Communication Systems

A brief history of attempts to use solitons for optical fiber communications and of the technical developments toward making soliton transmission practical is reviewed. The main problems affecting long-distance soliton transmission, as well as techniques to solve them, are described. Recent developments concerning the use of dispersion management and some of the remarkable properties of dispersion managed solitons are also discussed.     

Optical Solitons in Fibers for Communication Systems

Abstract

A brief history of attempts to use solitons for optical fiber communications and of the technical developments toward making soliton transmission practical is reviewed. The main problems affecting long-distance soliton transmission, as well as techniques to solve them, are described. Recent developments concerning the use of dispersion management and some of the remarkable properties of dispersion managed solitons are also discussed.     

Dispersion-Managed Optical Solitons with Higher-Order Nonlinearity

In this paper we have investigated the propagation characteristics of optical solitons in dispersion managed optical communication systems taking into account of the effect of quintic nonlinearity. Using variational formalism, several ordinary differential equations have been established for pulse parameters. These equations have been solved numerically to investigate the propagation characteristics. It has been noticed that stable periodic pulse propagation is possible over long distance. Numerical simulation has been undertaken to show that parabolic nonlinearity reduces collision distance between neighbouring pulses of the same channel.     

Prospects for neutron spectrometry of new-type bound multiphonon solitons and bisolitons generated by ultrasound and hypersound

It has been shown using the molecular dynamics method that new-type solitons and bisolitons are generated under the action of pulsed of ultrasound and hypersound on the crystalline single-atom materials. The dispersion curve of new-type bisolitons adjoins the dispersion curve of conventional solitons. A subsonic compression soliton is found, the dispersion curve of which intersects the phonon dispersion curve. Nuclei of new phases are generated under the inelastic collision of solitons in the fcc and hcp crystal systems at the early stage of structural phase transitions. The solitons of the new undulator type, which generate nuclei, are found. Characteristics of solitons and bisolitons in crystal lattices of uranium and plutonium are presented.     

Reduced-power optical solitons in fiber lines with short-scale dispersion management

We examine the properties of dispersion-managed (DM) solitons in fiber lines with dispersion-compensation period L much shorter than amplification distance Z(a) . DM solitons in systems with short-scale dispersion compensation have reduced power compared with DM solitons in previously studied regimes with L>/=Z(a) power (for the same local and average dispersion and the same pulse width). As a result, chirped DM soliton transmission with reasonably low power can be realized with shorter pulses when DM solitons in systems with large L/Z(a) ratios have energies that are too high to be used in practice.     

色散管理孤子中 Raman效应引起的时移及定时抖动

给出了色散管理孤子中Raman效应所引起的脉冲中心位置时移的解析表达式并讨论了孤子脉宽的波动所引起的Raman定时抖动.结果表明:时移的演化和不同的色散配置有关,并且色散管理孤子Raman时移和常规孤子一样与传输距离及平均色散的平方成正比,但是比常规孤子的比例大.     

Dispersion-Managed Optical Solitons with Higher-Order Nonlinearity

In this paper we have investigated the propagation characteristics of optical solitons in dispersion managed optical communication systems taking into account of the effect of quintic nonlinearity. Using variational formalism, several ordinary differential equations have been established for pulse parameters. These equations have been solved numerically to investigate the propagation characteristics. It has been noticed that stable periodic pulse propagation is possible over long distance. Numerical simulation has been undertaken to show that parabolic nonlinearity reduces collision distance between neighbouring pulses of the same channel.     

Self-equalization of energies of solitons in transmission systems by guiding filters

In this paper, the regulating effect of guiding filters on the energies of solitons in wave-length division multiplexing (WDM) transmission systems is rigorously studied. More precisely, it is shown that guiding filters prevent the energies of solitons from decaying to zero in long distances. This goal is achieved by studying a mathematical model of the evolution of energies of solitons in transmission systems. The approach is mathematical and does not use numerical or experimental results available in the literature; nevertheless, it reaffirms such results.     

Mathematical theory of slow light optical solitons

This paper studies the dynamics of slow light optical solitons from a mathematical point of view. It is mathematically proved that optical solitons, with a proper choice of time-dependent coefficients of dispersion and nonlinearity, can be made to slow down, and in the limiting case, to zero velocity. The types of nonlinearity that are studied in this paper are the Kerr law, power law, parabolic law, dual-power law and log law. Both bright and dark solitons are studied.     

Effect of group-delay ripples on dispersion-managed soliton communication systems with chirped fiber gratings

The effect of group-delay ripples in dispersion-managed soliton communication systems that use chirped fiber gratings for dispersion compensation is studied. Using both a reduced model and direct numerical simulation, we find that dispersion-managed solitons exist even in the presence of large dispersion variation caused by group-delay ripples. The dispersion-managed solitons suppress the growth of intersymbol interference induced by the group-delay ripples.     

Dispersion and nonlinear management for femtosecond optical solitons

We consider the concept of femtosecond propagation for optical solitons in a dispersion management fiber and study the optimal amplification of optical solitons through dispersion wells and barriers and also for the dispersion tailored profile case. For the former, we observed periodic soliton trapping for the in-phase injection case when their respective velocities were equal and opposite with their amplitudes being unequal and no soliton trapping for the off-phase injection case when the two pulses are having a phase difference of π. For the latter, we observed an enormous amplification of the soliton pulses which is one of our main results in this Letter.     

非均匀光纤中暗孤子传输特性研究

由于变系数非线性Schrödinger方程的增益、色散和非线性项都是变化的, 根据方程这一特点可以研究光脉冲在非均匀光纤中的传输特性. 本文利用Hirota方法, 得到非线性Schrödinger方程的解析暗孤子解. 然后根据暗孤子解对暗孤子的传输特性进行讨论, 并且分析各个物理参量对暗孤子传输的影响. 经研究发现, 通过调节光纤的损耗、色散和非线性效应都能有效的控制暗孤子的传输, 从而提高非均匀光纤中的光脉冲传输质量. 此外, 本文还得到了所求解方程的解析双暗孤子解, 最后对两个暗孤子相互作用进行了探讨. 本文得到的结论有利于研究非均匀光纤中的孤子控制技术.     

Dispersion managed dissipative solitons with higher order nonlinearity and frequency-selective feedback

We present the generation and interaction dynamics of dispersion managed soliton in a dissipative cubic-quintic nonlinear optical fiber coupled with frequency-selective feedback. Analytically, perturbative variational method is used to obtain evolution equations for different soliton parameters that are subsequently solved to study the propagation characteristics of the dispersion managed dissipative solitons (DMDS). The DMDSs show breather like characteristics and are found to be robust against certain level of initial noise. Both the standard Gaussian and more generic super-Gaussian pulse profile are shown to yield stable DMDS. Interaction of two DMDSs of same phase may lead to a bound state. By varying the temporal separation and phase difference between the DMDSs the bound state can be switched between low to high speed regime.     

色散渐变光纤中相移控制研究

相移控制能有效的避免孤子间的相互作用.通过利用符号计算和双线性方法,本文解析研究用于描述色散渐变光纤传输特点的非线性Schr?dinger方程,并得到该方程的双孤子解.基于所得到的双孤子解,通过研究发现,当色散渐变光纤中的群速度色散呈Gauss型变化时,可以利用该类光纤实现孤子相移控制,从而避免孤子相互作用,提高光通信系统中信号传输质量.此外,本文还将讨论色散渐变光纤中各类参数对相移控制的影响.本文结论还有助于逻辑门和全光开光的研究.     

非均匀系统中非自治孤子的色散和非线性管理

基于包含自发拉曼散射和外电光调制效应的非自治非线性薛定谔方程,采用简单的变换方法,解析研究了三种非均匀系统中非自治孤子的管理和传输。结果发现,在非均匀的非线性渐增或色散渐减光纤系统中都存在精确的啁啾非自治孤子解,都可以实现孤子的放大和压缩,但具有不同的速度、频移和啁啾特性;而在非均匀的色散和非线性均渐减光纤系统中,可以支持无啁啾的非自治孤子,该孤子具有不变的脉宽和振幅以及振荡衰减的速度,孤子的频移仅由自发拉曼散射决定。同时,数值模拟结果进一步证实在三种非均匀管理系统中都可支持非自治孤子的传输。该研究结果为实际非均匀孤子管理系统中实现孤子的压缩和传输提供了理论依据。     

Angular pseudomomentum theory for the generalized nonlinear Schrödinger equation in discrete rotational symmetry media

We develop a complete mathematical theory for the symmetrical solutions of the generalized nonlinear Schrödinger equation based on the concept of angular pseudomomentum. We consider the symmetric solitons of a generalized nonlinear Schrödinger equation with a nonlinearity depending on the modulus of the field. We provide a rigorous proof of a set of mathematical results justifying that these solitons can be classified according to the irreducible representations of a discrete group. Then we extend this theory to non-stationary solutions and study the relationship between angular momentum and pseudomomentum. We illustrate these theoretical results with numerical examples.