应用相敏光放大器抑制光孤子互作用的研究

通过计算机系统仿真研究了应用相敏光放大器(PSA)作为在线放大器抑制光孤子传输系统中孤子间的互作用，并与相应的掺铒光纤放大器(EDFA)光孤子系统进行比较。仿真中考虑了平均孤子和动态孤子两种传输方案。结果表明，应用相敏光放大器代替掺铒光纤放大器作为在线放大器能有效地抑制孤子系统中脉冲的展宽和孤子间的互作用。对于平均孤子，在没有附加其他孤子控制措施的情况下，相敏光放大器系统中孤子间互作用得到有效的抑制，孤子对稳定传输距离得到极大的延长。对动态孤子，相敏光放大器亦表现出良好的抑制孤子间互作用的效果，但孤子脉冲的幅度经长距离传输后显著下降。     

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。     

PSA平均光孤子系统传输性能的研究

本采用计算机系统仿真的方法，研究了应用相敏光放大器(PSA)作为在线放大器的采用平均孤子传输方案的光孤子通信系统中，泵浦光与信号光之间的相位漂移、光纤色散对光孤子通信系统传输性能的影响。仿真的结果表明：泵浦光与信号光之间的相位漂移将导致孤子幅度的下降；由于PSA增益的相敏特性，光纤色散导致孤子脉冲主瓣幅度下降，脉宽展宽，出现旁瓣。     

在线放大器为PSA的动态孤子通信系统传输性能受光纤色散参量影响的研究

通过计算机系统仿真研究光纤色散参量对以相敏光放大器(PSA)作为在线放大器的动态孤子系统传输性能的影响。研究结果表明,PSA增益的相敏特性使孤子脉冲主瓣幅度因光纤色散而下降,脉宽展宽,出现旁瓣。光纤色散值越大,经长距离传输后,孤子脉冲主瓣的下降幅度和脉宽展宽程度越显著;且旁瓣脉宽越宽。     

PMD对平均光孤子系统传输性能影响的研究

文章采用计算机系统仿真的方法,通过数值求解简化的基本传输方程和非线性薛定谔方程,研究了采用相敏光纤参量放大器(PSA)作为在线放大器时,偏振模色散(PMD)对系统传输性能的影响.系统传输方案采用平均孤子系统.仿真结果表明:当PMD系数增大时,孤子脉冲出现分裂和展宽,幅度出现衰减,从而导致系统的传输性能下降.     

增加孤子系统放大器间距的新方法

仅利用控制孤子的无源量子势阱饱和吸收器和窄带滤波器，可使远距离孤子系统的光放大器间距增大到１００ｋｍ，在所推荐的系统中，以１０Ｇｂ／ｓ传输９００ｋｍ后孤子互作用效应和戈登－豪斯抖动效应所致的误码率小于１０＾－９。     

放大器噪声对色散管理光孤子传输的影响

采用变分法讨论了放大器噪声对色散管理光孤子脉冲参数的影响。讨论了ASE噪声对脉冲相位、脉冲中心时间和中心频率的影响，并且对比讨论了采用密集色散管理系统和降低平均色散值后，ASE噪声对脉冲的影响，结果表明：密集色散管理孤子系统和平均色散接近于零的色散管理系统更有利于降低放大器噪声对脉冲的扰动。     

孤子能量增强对色散管理孤子系统性能的影响

本文采用数值系统仿真的方法,通过比较孤子功率增强输入和孤子基态功率输入时,孤子脉冲的传输波形,分析孤子功率增强对色散管理孤子系统传输性能的影响。结果表明,在色散管理孤子系统中,采用功率增强输入可以非常好的提高长距离系统传输性能。     

光孤子通信研究进展

在回顾光孤子通信研究发展概况的基础上,综述了光孤子通信技术的最新发展,展望了未来光孤子通信研究动态及发展前景。国外光孤子通信研究工作自１９７３年以来大致经历了３个阶段。我国从１９８４年开始这方面的理论研究。目前超长距离光孤子通信系统的传输方案,主要采用集总式掺饵光纤放大器作为中继技术,分为平均传输方案和动态孤子传输方案两种。     

随机高阶效应对孤子传输系统的影响

基于高速传输的超短光孤子脉冲传输系统中存在不可忽略的高阶效应，研究了随机高阶效应的扰动对孤子系统的影响。结果表明：随机高阶效应引起孤子到达时间抖动而降低了孤子传输系统的容量，其中随机三阶色散引起的孤子到达时间抖动方差与传输长度的三次方成正比，随机非线性色散和随机随时间变化的三阶非线性引起的孤子到达时间抖动方差与传输长度的一次方成正比     

The Effect of System and Amplifier Parameters on the Performance of Average Soliton Transmission System Using PSA as In-Line Amplifier

In this paper,the effect of system and amplifier parameters on the performance of soliton transmission systemusing Phase Sensitive Amplifier(PSA)as in-line amplifier has been researched theoretically by computer simulation.Since in PSA soliton system the performance of average soliton regime is much better than that of dynamic soliton regime,in our simulation we only considered average soliton regime.Our simulation results show that although using PSA as in-line amplifiers in soliton system can not only overcome Gordon-Haus restriction but also suppress solitons interaction,lengthen soliton stable transmission distance significantly,the system and amplifier parameters have to be chosen carefullyin order to get a better system perorformance.     

Automatic intensity control of an optical transmission line usingenhanced gain saturation in cascaded optical amplifiers

The output characteristics through an optical transmission system with multiple optical amplifiers which operates in the gain-saturation regime have been studied in both a uniformly pumped laser amplifier and an erbium-doped fiber amplifier with pump absorption. It has been shown that the output intensity becomes almost constant in the optical system if the input intensity changes within the gain-saturation regime of the amplifiers. The stabilization of the output intensity is greatly enhanced by cascading the saturated optical amplifiers. There is a characteristic input intensity which causes no intensity changes at the output end of the transmission line. This technique is applicable to soliton transmission as well as to ordinary pulse communications     

Maximum transmission capacity of a soliton communication system with lumped amplifiers

For a soliton transmission system which uses lumped optical amplifiers with a fixed amplifier spacing and a fixed bit rate, the optimum input pulse width and input amplitude are presented to maximise the soliton transmission distance. In a 10 Gbit/s soliton system with a repeater spacing of 40 approximately 50 km, a pulse width of 20 ps, and an amplitude of 1.4 approximately 1.8, the limitation owing to mutual soliton interaction is negligible compared with that resulting from the interaction between amplifier noise and the soliton pulse, and the soliton pulse can propagate up to the Gordon-Haus limit.<>     

Transmission limitations due to self-phase modulation in opticalPSK heterodyne detection systems employing chromatic dispersionequalization

Even if the amplitude of a phase-modulated optical signal is constant before transmission, amplitude modulation is caused by fiber chromatic dispersion. As a result, self-phase modulation (SPM) is induced. In optical heterodyne detection, SPM cannot be compensated for by the delay equalizer (electrical domain) used to compensate fiber chromatic dispersion. However, the transmission distance limitation of multi-repeatered coherent transmission systems has not been investigated in the presence of SPM. This paper theoretically and experimentally investigates the transmission distance achievable with a phase-shift-keying (PSK) heterodyne detection system employing in-line optical amplifiers and delay equalization. The calculated results show that equalization is effective when γP₀/2B²|β₂|<10 in the normal dispersion regime, and γP₀/2B²|β ₂|<15 in the anomalous dispersion regime. Furthermore, the increase in transmission distance achieved by using equalization is experimentally shown in an 8 Gb/s PSK heterodyne transmission experiment using a conventional single-mode (SM) fiber and in-line fiber amplifiers     

Long-distance optical soliton transmission with lumped amplifiers

A soliton transmission method using lumped amplifiers is presented which is named the preemphasis method. An N=1 soliton with relatively high amplitudes (1.2<A<1.4), which is used as an input soliton, plays an important role in the lumped-gain soliton transmission system. The initial soliton pulse width can be preserved after propagation over long distance despite the existence of fiber loss. It is shown that with the lumped gain, the soliton pulse can propagate over more than 9000 km when the repeater spacing is 31 km and fiber loss is 0.22 dB/km     

注入幅度失配平均孤子自稳定传输

分析平均孤子传输系统中光源注入脉冲幅度失配对光脉冲传输稳定性产生的影响,提出利用工作在饱和区的光纤放器实现系统中脉冲自稳定传输的方案,并验证了这一措施的可行性。     

400 Mbit/s, 372 km coherent transmission experiment using in-lineoptical amplifiers

Reports on an optical transmission experiment using four in-line optical amplifiers. With a net gain of 58000 (47.7 dB) from the amplifiers, the authors were able to increase the longest nonregenerated transmission distance to 372 km. The system penalty associated with the amplifiers was only 1.5 dB