Soliton-like pulse timing jitter in dispersion-managed systems

In this paper, the timing jitter in dispersion-managed soliton-like systems with the Gaussian pulse is studied by using two methods. Firstly, the derivation of the dynamic equations for the evolution of soliton-like parameters and the timing jitter expressions for the dispersion-managed soliton-like systems are carried out by the perturbed variational method. By analysing and simulating these timing jitter expressions, one can find that the timing jitter is induced by the amplified spontaneous emission noise and the frequency shift, etc. Nonlinear gain can suppress the timing jitter. The chirp sign and the filters action have also effects on the total timing jitter. Secondly, the timing jitter is calculated and analysed by using the moment method. The results of the two methods prove to be consistent with each other.     

Gordon–Haus timing jitter in dispersion-managed systems with distributed amplification

The moment method is used to study the Gordon–Haus timing jitter of optical pulses in dispersion-managed communication systems with distributed amplification. Timing-jitter formulas are derived for the dispersion-managed soliton and chirped return-to-zero formats. These formulas are used to study the effects of dispersion compensation on timing jitter. Just as distributed amplification reduces the amount of amplifier noise, so also does it reduce the timing jitter caused by amplifier noise. For both transmission formats, one can reduce the timing jitter significantly by choosing the amount of dispersion compensation judiciously.     

Studies on Timing Jitter in WDM Dispersion-Managed System by Variational Method

The variational method is employed to describe the basic properties of soliton parameters and to evaluate the timing jitter by considering multi-perturbations in wavelength-division-multiplexing (WDM) dispersion-managed soliton (DMS) system. The bit error rates (BER) of different dispersion managed systems, which induced by the timing jitter are given and compared. From that, there exist optimizations for the design of high-speed and long-distance practical WDM soliton system.     

在时域和频域控制下色散管理孤子系统的定时抖动

利用变分法研究了时域和频域的控制技术同步幅度调制器和固定频率滤波器对色散管理孤子系统的作用.得到了计算定时抖动的解析表达式,利用得到的公式,可以计算不同控制参量时,孤子系统定时抖动的大小,从而优化同步幅度调制器和固定频率滤波器的设计.结果也证明了滤波器对喇曼效应引起的时间抖动的抑制作用.     

Phase jitter in periodically dispersion-managed optical transmission systems

We investigate the phase jitter in long-haul optical transmission systems with periodic dispersion management and amplification. We compare different dispersion-managed soliton systems and a conventional soliton system having the same pulse width and path-averaged dispersion. Using the variational method, we derive the ordinary differential equations for the pulse parameters perturbed by amplifier noise and hence calculate the phase jitter. We verify the analytical results by numerically solving the nonlinear Schrödinger equation using split-step Fourier algorithm. The results suggest that the reduction of nonlinear phase noise in dispersion-managed soliton systems is possible compared to a conventional soliton system. It is also revealed that the phase noise is enhanced in stronger dispersion-managed systems. We also explore the phase noise effect in dispersion-managed quasi-linear systems and find that phase jitter is mitigated in highly dispersive fibers.     

Effects of precompensation and postcompensation on timing jitter in dispersion-managed systems

We present an analytic theory of timing jitter in dispersion-managed light-wave systems that is based on the moment method and the assumption of a chirped Gaussian pulse. We apply the theory to a soliton system and show that 50% postcompensation of the accumulated dispersion can reduce the jitter by a factor of 2. We also apply the theory to a low-power light-wave system employing the return-to-zero format and find that timing jitter can be minimized along the fiber link for an optimal choice of precompensation and postcompensation.     

Gordon Haus effect in dispersion-managed soliton systems

We derive an expression for the timing jitter of a soliton owing to amplifier noise in dispersion-managed fiber systems. We show that the timing jitter is a function of the pulse width as well as of the chirp at the amplifier location and that it can be minimized by a proper choice of the amplifier position relative to the dispersion map.     

Analysis of soliton collisions in a wavelength-division- multiplexed dispersion-managed soliton transmission system

Timing jitter induced by soliton collisions is the leading nonlinear penalty in wavelength-division-multiplexed (WDM) dispersion-managed soliton transmission. Through analysis and numerical simulations we show that consecutive complete collisions together with partial collisions at the system output cause approximately the same amount of timing shift as partial collisions at the system input. We further show that the worst-case timing shift diverges logarithmically with the total number of WDM channels and linearly with the total transmission distance. However, the probability for such worst cases to occur decreases exponentially with channel spacing, total number of WDM channels, and transmission distance. We conclude that only the effects caused by adjacent channels need to be considered in a high channel count WDM system.     

The Choice of Dispersion Managed Schemes in Standard Single-Mode Fiber

In this paper, the three allocated schemes of dispersion-managed soliton are proposed on standard single-mode fiber. Adopting variational method and on the proposed schemes, the timing jitter introduced from the perturbations of amplifier spontaneous-emission (ASE) and cross-phase modulation in wavelength-division multiplexing is studied. Compared with performances of different system schemes, the principles of optimal allocated dispersion management are obtained, which can be used to optimal allocated dispersion managed soliton system.     

Reduction of phase jitter in dispersion-managed systems by in-line filtering

The influence of in-line filters on the phase jitter of chirped optical pulses propagating in arbitrary dispersion-managed systems is studied with a semianalytic moment method. Because of its stabilizing effect on the amplitude, filtering reduces the nonlinear phase jitter that accumulates through self-phase modulation. As in the case of constant-dispersion soliton links, we observe that the phase variance grows only linearly with distance in the presence of filtering. Phase jitter reduction is observed and accurately predicted by the moment method in two dispersion-managed systems with different levels of nonlinearity and filter strength.     

Periodic dispersion management in soliton wavelength-division multiplexing transmission with sliding filters

We compare the performance of dispersion-managed fibers with that of dispersion-decreasing fibers and of fibers with uniform dispersion in filtered soliton wavelength-division multiplexing transmission. Alternating-sign dispersion management allows us to achieve values of collision-induced timing jitter that are comparable with what can be achieved by use of dispersion-decreasing fiber and are lower for some parameter values.     

Collisions in dispersion-managed soliton propagation

We study collisions in dispersion-managed soliton propagation for wavelength-division multiplexing application at zero net dispersion when the Gordon-Haus timing jitter is removed. We show that the collisions can lead to group-velocity changes and spectral collapse. Large channel separation ameliorates the effects. Filters prevent spectral collapse but do not affect the velocity changes.     

Timing-jitter reduction in a dispersion-managed soliton system

We found by using Monte Carlo simulations that the timing jitter in a dispersion-managed soliton system decreases as the strength of the dispersion management and hence the ratio of the pulse energy to the pulse bandwidth increases. The results are in qualitative but not quantitative agreement with earlier predictions that the decrease is inversely proportional to the square root of the pulse energy. Using an improved semi-analytical theory, we obtained quantitative agreement with the simulations.     

Collision-induced timing shifts in dispersion-managed soliton systems

The frequency and timing shifts associated with dispersion-managed solitons in a wavelength-division multiplexed system are computed by the numerically efficient Poisson sum technique. Analytical formulas are attainable by use of this approach with a Gaussian approximation for the soliton. The results are favorably compared with known results for the frequency shift. The method also applies to quasi-linear return-to-zero transmission formats.     

Efficient modeling of phase jitter in dispersion-managed soliton systems

The variational method is used to derive correlation equations that model phase jitter in dispersion-managed soliton systems. The predictions of these correlation equations are consistent with numerical solutions of the nonlinear Schr?dinger equation on which they are based.     

Noise-induced amplitude and chirp jitter in dispersion-managed soliton communications

An analytic theory is presented that demonstrates that noise-induced amplitude and quadratic chirp jitter in a dispersion-managed soliton system can impose a fundamental transmission limit. Using a variational method, we show that the nonlinear amplitude and chirp dynamics are well approximated by a two-dimensional random-walk process.     

脉冲内拉曼散射影响下的孤子之间的相互作用及其控制

研究了脉冲内拉曼散射效应影响下的同相和反相相邻孤子脉冲之间的相互作用,分析了孤子之间的相互作用对定时抖动的影响和脉冲内拉曼散射效应对孤子频移的影响。研究结果表明:在脉冲内,在拉曼散射效应的影响下,同相基态孤子脉冲的周期性离合被破坏了,两孤子脉冲一次碰撞后一直处于排斥状态,并且在碰撞后自频移现象十分明显;反相孤子脉冲的影响则较弱,两孤子脉冲都向下降沿发生偏移。引入非线性增益可以有效地控制孤子之间的相互作用,抑制自频移效应和稳定孤子传输。     

Timing jitter owing to intrachannel pulse interactions in dispersion-managed transmission systems

We study interaction-induced timing jitter in single-channel dispersion-managed return-to-zero ttransmission systems operating at high map strengths. An equation for the frequency and timing shifts of two interacting pulses is derived by a variational approach. The interaction can be of either an attractive or a repulsive character, and we show that the resultant timing jitter can be reduced by proper design of the dispersion map.     

色散控制光孤子系统性能分析

研究色散控制光孤子系统中的放大器的自发辐射噪声与交叉相位调制对孤子传输特性的影响，采用变分法分析了色散控制孤子的均方频移、定时抖动和误码特性，从降低自发辐射噪声和交叉相位调制扰动引起的均方频移出发，确定了补偿段的特性参量，给出了三种传输控制方案，分析了各方案中色散控制孤子的传输特性，其结果对色散控制孤子系统的设计具有参考价值。     

Non-Gaussian statistics of soliton timing jitter induced by amplifier noise

Based on first-order perturbation theory of the soliton, the Gordon-Haus timing jitter induced by amplifier noise is found to be non-Gaussian distributed. Both frequency and timing jitter have larger tail probabilities than Gaussian distribution given by the linearized perturbation theory. The timing jitter has a larger discrepancy from Gaussian distribution than does the frequency jitter.