DPSK色散管理孤子系统的稳定传输

DPSK调制方式和色散管理孤子(DMS)传输方案相结合的新的传输机制能抵制噪声和非线性损伤,在高速多通道光传输系统中具有突出优点。采用变分法研究同时存在光纤损耗、ASE噪声、孤子互作用等多种扰动因素的DPSK色散管理孤子系统的传输特性,在频域导频滤波控制方案下,导出了孤子各特征参数随传输距离的演化方程。对40 Gb/s长距离DPSK色散管理孤子系统的传输特性进行了数值模拟,其结果和理论分析一致。并通过Optisystem软件作进一步仿真,论证了该系统零频移稳定传输的可行性。     

NOLM对短皮秒光孤子传输的控制

研究了非线性光纤环境（ＮＯＬＭ）在短皮秒光孤子传输中的控制作用,分析了ＮＯＬＭ结构扼制色散波的能力及孤子系统的稳定性,并用数值模拟方法研究了超高速光孤子系统中ＮＯＬＭ对色散波和喇曼自频移的扼制作用,显示出良好的控制效果。     

OTDM高速孤子传输系统的稳定性研究

该文首次在同时考虑3种高阶效应和孤子互作用的条件下,应用变分法,导出了孤子各特性参数随传输距离的演化方程,基于此方程应用线性扰动法,从理论上导出了稳定性条件,论证了160 Gb/s高斯准孤子系统零频移稳定传输的可行性,并设计出一个比特率为160 Gb/s高速长距离孤子通信系统,对其性能进行数值模拟仿真,其结果和理论分析一致。     

超短光孤子定时抖动控制方案的研究

文章使用时域和频域的综合控制方案,分析了光脉冲的传输演化方程,研究了飞秒和短皮秒光孤子在高阶效应作用下定时抖动的影响,分析了该方案对定时抖动控制的可行性和有效性。设计了160Gb/s长距离孤传输系统,并对其定时抖动特性进行了数值模拟,模拟的结果与理论分析基本一致,文章结论对于设计高速长距孤子系统具有参考价值。     

色散控制孤子系统中光纤偏振模色散的滤波控制

本文研究高速OTDM色散控制孤子系统偏振模色散的影响及其滤波控制.首先建立了同时考虑偏振模色散和滤波控制时的DMS传输方程,其次采用变分法给出了滤波控制常双折射光纤中DMS传输方程的变分解,求得了DMS的特征参数的传输演化规律,然后研究了滤波控制随机双折射光纤中DMS传输稳定性问题及其定时抖动规律.最后基于变分所得定时抖动公式,分析了三种不同系统的定时抖动,显示了DMS系统中用滤波器抑制PMD时,对高速光孤子通信性能的影响是非常有效的.     

TOD效应对超短光孤子脉冲自频移的影响研究

对包括拉曼散射和TOD（Third-Order Dispersion）效应在内的超短光孤子脉冲传输的特性分析的基础上，通过数值模拟、分析、拟合得出了TOD效应引起的孤子自频移量与距离（Z）、脉冲宽度（T0）和参量 之间的量化关系。完善了以前只考虑拉曼散射效应的孤子频移量的计算公式。对孤子自频移引起的脉冲延时进行了研究。研究结果表明由TOD效应引起的孤子频移量 ，孤子总的脉冲延时量 ，由TOD效应引起的孤子脉冲延时 。该结果为研究基于飞秒量级的高速光开关有重要的意义。     

光孤子传输控制方案的探讨

文章首先分析了光孤子通信系统的限制因素,包括光纤损耗、孤子间的相互作用、各种高阶效应以及参量随机变化等.然后在此基础上,讨论了光孤子通信系统的传输控制方案,并分析比较了这些方案的优缺点,对光孤子系统设计具有参考价值.     

相敏光放大器增益对平均光孤子系统传输性能的影响

采用计算机系统的仿真方法研究应用相敏光放大器(PSA)作为在线放大器的平均光孤子系统中PSA的增益对孤子系统传输性能的影响。仿真的结果表明：由于PSA增益的相敏特性，孤子脉冲经PSA放大后会出现能量损失，导致长距离传输后脉冲幅度下降。适当调高放大器增益能够补足孤子能量的损失，显著延长孤子的稳定传输距离。但是，如果系统中色散波较大，放大器增益的微调量也相应较大。而过大的放大器增益会使得孤子脉冲经PSA放大后出现显著的旁瓣，长距离传输后旁瓣能量的积累将导致孤子间严重的互作用，劣化系统的传输性能。因此，适当提高放大器增益只能在一定范围、一定程度上改善系统的传输性能。     

色散管理孤子色散周期长度的开关特性

在色散管理光孤子系统中建立起一种周期扰动模型,研究了扰动对孤子传输的影响.运用快速傅里叶变换方法通过数值模拟发现,在脉冲传输距离与扰动周期长度的关系中不仅存在着多极值结构,而且存在着开关特性,利用这一特性可以有效地控制孤子的传输.     

应用相敏光放大克服光孤子传输系统中Gordon-Haus限制的研究

通过计算机系统仿真研究了应用相敏光放大器(PSA)作为在线放大器的光孤子传输系统，并与相应的掺铒光纤放大器(EDFA)光孤子系统作了比较。仿真了平均孤子和动态孤子两种传输方案．研究结果表明，由于PSA不存在ASE噪声，应用PSA作为在线放大器可以克服光孤子系统中的Gordon-Haus限制．对平均孤子，在没有附加其它的孤子控制技术的情况下，PSA系统孤子的稳定传输距离得到极大的延长．对动态孤子，PSA亦表现出良好的抑制脉冲展宽效果，但脉冲的幅度经长距离传输后显著下降．     

High-order Nonlinearity Influence on Performances of High Rate Soliton Communication System and its Suppression Method

The propagation equation is established to investigate the feasibility and the validity of the suppression of the soliton self-frequency shift(SSFS) in the picosecond and femtosecond soliton communication system employing a compound control method of time domain and frequency domain . By the use of the variational approach, the evolution of the chirping Gaussian quasi-soliton pulse is analyzed in the presence of intrapulse Raman scattering. The self-frequency shift(SFS) is eliminated by an up frequency-guiding filter control method. The soliton perturbation method is employed to study the steady-state solutions in the presence of intrapulse Raman scattering. The relation between the transmission performances of the soliton and the system construction parameters such as 3dB-temporal width of the modulator, center frequency and bandwidth of the filter is deduced and a stable transmission condition is revealed. The long-haul soliton transmission system without SSFS at the rate of 160 Gb/s is designed and its performance is numerically simulated. The simulation results are in well within accordance with our theoretical analysis. This work is supported by the National Natural Science Foundation of China (Grant No.60072046).     

Compton散射下的3阶色散对超短光孤子脉冲自频移的影响

应用多光子非线性Compton散射模型,对Compton散射下的3阶色散对超短光孤子脉冲自频移的影响进行了研究,通过理论分析、数值模拟和拟合,结果表明,Compton散射使3阶色散对孤子自频移有较强的抑制作用,在时域中引起孤子脉冲的调制振荡结构更为明显,频域中的频谱被分为两个较清晰的、峰值较高的谱峰,孤子自频移 ,但其斜率不同于散射前的斜率。     

修正高阶非线性薛定谔方程的显式行波解

利用扩展的双曲正切函数法,并借助于符号计算软件Map le,研究了考虑自陡峭效应、 自频移效应后的修正高阶非线性薛定谔方程,获得了多组显示精确行波解,主要包括亮孤子解、暗孤子解和一种新形式的复合孤子解。讨论了这3种飞秒孤子解存在的参量条件,并指出了飞秒亮孤子解存在于负三阶色散区域,而飞秒暗孤子解则存在于正三阶色散区域。     

分布放大传输系统中暗孤子链的传输特性研究

研究了由低掺杂浓度的分布式掺铒光纤级联传输系统中,多个暗孤子组成的暗孤子链的传输特性,结果表明：在分布放大传输中,奇或偶数个暗孤子组成的暗孤子链的传输特性存在较大的差异,其中奇数个暗孤子组成的暗孤子链的传输稳定性较好,而偶数个暗孤子组成的暗孤子链在传输过程中存在明显的由暗孤子相互作用引起的孤子自频率漂移和孤子变形。     

Soliton position jitter caused by periodic amplification andself-frequency shift

The formula for soliton timing jitter due to self-frequency shift and pulse width fluctuations caused by spontaneous-emission noise has been deduced. Such timing jitter is compared with that caused by the carrier frequency shift due to spontaneous-emission noise. It is shown that the timing jitter due to the self-frequency shift can be as large as the timing jitter due to carrier frequency shift when the total transmission distance is 100 times longer than the soliton period     

Cross-correlation measurement without mechanical delay scanningusing electronically controlled wavelength-tunable femtosecond solitonpulse

A novel cross-correlation measurement system without mechanical action has been demonstrated in which the delay time between the reference and signal pulse can be electronically scanned by utilising the soliton self-frequency shift and the chromatic dispersion in the optical fibre. In this system, the reference pulse is the ideal femtosecond soliton pulse. The scanning range, the resolution and the scanning speed of the delay time can be arbitrarily changed only by the electronic control     

Numerical study of moderate distance high bit-ratealternating-amplitude soliton systems

We present a numerical investigation of alternating-amplitude soliton systems. We propagate 100 Gb/s, pseudorandom bit sequences of 2 ⁵-1 to 2⁷-1 solitons through fibers of different lengths and calculate the corresponding eye opening penalty at the receiver. The influence of different amplitude ratios, amplifier spacings, pulse widths, and dispersion slopes as well as of the soliton self-frequency shift are studied. We also study the effect of compression of the alternative-amplitude solitons with the larger amplitudes to preserve their soliton character and the impact of the relative initial phase between the alternating-amplitude solitons. When the amplifier spacing is 10 km the system length can be at least 400 km with alternating-amplitude solitons compared to only 200 km in the case of equal amplitude solitons with similar penalties. Our simulations show-that third-order dispersion and the soliton self-frequency shift limit the maximum allowable amplitude ratio     

Theory of soliton pulse forming in an actively modelocked fiberlaser

Generation of subpicosecond solitons in active modelocked fiber lasers is investigated, both analytically and numerically. The laser model takes into account the pulse dispersive spreading, self-phase modulation, finite amplification bandwidth, pump depletion and Raman self-frequency shift. Our analytical theory, which is based on the inverse scattering method perturbation approach, allows us to calculate the steady-state parameters of the soliton pulse. The analytic predictions are confirmed by numerical simulation. It is shown that the minimal pulse duration may be achieved provided that the Raman self-frequency shift is suppressed by the phase modulator     

Tunable Raman Soliton Source Using Mode-Locked Tm–Ho Fiber Laser

We report a femtosecond pulse source that uses a mode-locked Tm-Ho oscillator and a self-frequency shift of Raman solitons in Tm-Ho power amplifier. The master oscillator mode-locked by an antimonide-based saturable absorber mirror produces 750-fs transform-limited soliton pulses over the tuning range from 1912 to 1972 nm. The soliton self-frequency shift in the amplifier resulted in transform-limited pulses with the wavelength adjusted by varying the amplifier pump power. We obtain ~150-fs soliton pulses at the wavelength of 2150 nm with average power up to 230 mW corresponding to the peak power of 27 kW. The efficiency of Raman conversion ranges from 47% to 62% over the tuning range     

Soliton self-frequency shift accelerated by femtosecond soliton interaction

Nonlinear interaction between femtosecond solitons has been investigated in a distributed erbium-doped fibre amplifier (DEDFA). It is shown that when the input femtosecond soliton pair is in phase, the soliton self-frequency shift is greatly accelerated by soliton interaction.<>