脉冲初始啁啾对色散管理孤子传输性能的影响

本文数值分析了脉冲始啁啾对色散控制孤子传输性的影响,得出的结论为：适当地选择正的初始啁啾可以提高后补偿系统中孤子的传输特性;负啁啾可以提高前补偿系统中孤子的传输性能。初始啁啾参量的大小与色散补偿的结构以及平均输入功率有关,并提出对采用啁啾技术的色散管理孤子系统设计的新方法。     

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。     

近变换限制脉冲在色散管理孤子系统中的传输

对含频率啁啾的高斯脉冲在色散管理孤子系统中的传输进行了分析。结果表明初始啁啾的存在将使脉宽和幅度沿传输距离涨落,并引起能量加重因子的增加,还研究了由谱窗技术产生的近变换限制脉冲在色散管理孤子系统中的传输问题,结构表明,通过合适的能量加重,近变换限制脉冲传输非常稳定,且其性能比相应的均匀低色散孤子系统还好,这表明色散管理系统比均匀光纤系统在光孤子源方面具有更大的啁啾及波形容差。     

色散管理孤子的传输特性

论述了色散管理孤子的传输原理,并利用数值方法模拟了色散管理孤子在不同的传输模式中的传输,研究了色散管理孤子特性及其应用。研究结果表明,色散管理孤子具有很明显的周期性,尤其采用平均路径色散为0的模型传输性能更佳。     

色散控制孤子系统的三阶色散分析

对三阶色散在色散控制孤子系统中的特性做了深入分析,采用变分法分析了三阶色散对色散控制孤子的传输特性的影响,给出了各参数的演变特点,并通过数值仿真讨论了三阶色散对系统的演变特点,指出了三阶色散对系统的有害性和补偿的必要性。     

超短DM光孤子系统中自频移影响及其抑制方法

针对色散管理孤子系统中孤子幅度、脉宽等参数的动态周期变化特性,采用时域和导频滤波复合控制方法,建立了光脉冲的传输方程,研究了短皮秒DM光孤子系统中控制孤子自频移（SSFS）影响的可行性和有效性,采用变分法分析了高速DM啁啾高斯准孤子在喇曼自频移条件下传输演化特性,采用沿线上导频滤波控制方法,将自频移控制在设计范围内,稳定了孤子中心频率。对40Gbit／s长距离高速DM孤子传输系统的传输特性进行了数值模拟,所得结果与理论分析完全一致。     

密集型色散管理模式中DM孤子传输特性分析

本文以经典色散管理孤子的传输特性为参照,研究了单信道40Gbit/s密集型色散管理系统内色散管理孤子的诸多传输特性,证实了密集型色散管理模式相对于经典色散管理模式的优势所在,同时给出了系统最佳传输性能与入射功率、分段数、以及脉冲初始宽度等因素的数值关系。     

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.     

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.     

预啁啾对偏复用孤子技术的补偿

在导出自相位调制和交叉相位调制共同作用所致相位调制频率啁啾的基础上,数值研究了相位调制频率啁啾与初始啁啾的关系,并对有和无初始啁啾40Gbit/s归零码(RZ)在二阶和三阶色散完全补偿(路径平均色散为0)的色散管理偏振复用孤子传输系统中的传输效果进行计算。结果表明,在输入功率达到一定值时,初始啁啾参量C对相位调制频率啁啾的作用,决定着系统偏振复用孤子技术的成效及传输性能,适当选取初始啁啾参量C能够有效抑制偏振模色散,提高孤子脉冲稳定传输距离。     

20 Gb/s optical soliton data transmission over 70 km usingdistributed fiber amplifiers

20 Gb/s optical soliton data transmission is demonstrated over 70 km. Highly efficient distributed Raman amplifiers for fiber-loss compensation are realized by using high Δn dispersion-shifted single-mode fibers pumped by laser diodes. To achieve high bit rate transmission, optical multiplexing and demultiplexing techniques are also employed. The bit error rate (BER) performance dependence on the input peak power of the optical pulse is measured. No power penalty can be seen at the input peak power required for transmitting optical solitons while the BER performance degrades when decreasing the input peak power     

Performance sensitivity to system parameters in multiwavelength super-continuum sources

We determine the fundamental cause of performance variation as a function of system parameters, in supercontinuum (SC) sources in a normal-dispersive fiber, with high-order nonlinearity effects included. The variations in the sliced-pulse quality with respect to the soliton order N, the input peak power, the slicing filter bandwidth, as well as the optimization of the fiber length and the slicing wavelength, are numerically investigated. The results show that, at a constant average input power, narrower input pulses (or smaller N) can help achieve broader output spectrum but at the expense of degradation in the sliced-pulse quality. Better quality of the sliced pulses can be obtained by using a slicing filter with wider filter bandwidth. Besides, the input peak power is found to have significant impact on the choice of the suitable slicing wavelength. These results can facilitate the optimization of system parameters in designing SC sources for optical transmission applications.     

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.<>     

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.     

高功率远程泵浦传输系统的研究

针对远程泵浦传输系统高功率泵浦光传输受限问题,文章基于随机分布反馈光纤激光器的工作原理,创新性地提出了一种新型远程泵浦传输方案,通过高反射率的光纤布拉格光栅增强泵浦光的受激拉曼效应,输出目的泵浦光功率.对新型远程泵浦传输系统的传输性能进行了测试,测试结果表明,实验数据和理论计算数据一致;与传统远程泵浦传输系统相比,新型...     

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     

A minimum distortion transmission scheme under combined effects of chromatic dispersion and SPM based on optical time-domain fractional Fourier transformation

In this paper, an optical time-domain fractional Fourier transformation (FRFT) system is proposed to achieve the minimum distortion transmission under combined effects of chromatic dispersion and self-phase modulation (SPM). In the new method, the pulses operated as FRFT will propagate in a new domain, in which the waveform in time domain will keep nearly unchanged through the transmission. The novel method achieves a 400 km optical transmission for an optical pulse with the full width at the 1/e point of peak power of 80 ps without any dispersion compensation and the pulse offers a nice performance with negligible nonlinear distortion. Compared with the soliton communication, this scheme shows more advantages on linear and nonlinear distortions without strict restriction to input pulses.     

Joint Transmit Beamforming and Power Control for CDMA System

1　Introduction　Power control and beamforming are two main methods toreduce interference in CDMA cellular communication sys tem. In power control, the transmitters powers are constant ly adjusted when the instantaneous SIR is not equal to targetSIR, so that the quality of weak links is improved. Base sta tion equipped with antenna arrays may adjust their beam pat terns so that they have maximum gain towards the directionsof target mobiles and minimum gain towards the other direc tio…