WDM+EDFA+DCF光纤传输系统中色散补偿方案的分析

由于在ＷＤＭ＋ＥＤＦＡ光纤传输系统中使用常规单模光纤（ＳＭＦ）在１５５０ｎｍ窗口的大色散限制了传输距离,采用色散补偿光纤（ＤＣＦ）进行色散补偿是上前一种较为理想的方法。本文基于光纤ＷＤＭ＋ＥＤＦＡ＋ＤＣＦ的长距离传输系统,讨论了ＤＣＦ色散补偿对光纤非线性效应交叉相位调制和四波混频（ＦＷＭ）的影响,提出了采用ＤＣＦ集总、后置、非完全补偿的色散补偿方案,这种方案可合系统具有更佳的传输性能。     

基于DCF长距离光纤通信系统的色散补偿

通过介绍光纤色散的产生及其对传输系统的影响,引出了色散补偿技术.在多种色散补偿方法中,侧重探讨了色散补偿光纤(DCF)技术.基于DCF在标准单模光纤上传输2245 km的情况下进行了研究,获得了一些对实际色散补偿系统有参考价值的结论.     

光纤通信系统色散补偿方案的优化

为了优化光纤通信系统色散补偿方案,采用软件仿真的方法设计了一个用色散补偿光纤进行色散补偿的单信道通信系统,利用光纤环形镜的全反射特性使该系统的色散补偿方案得到了优化,补偿效果良好,并节约了成本。对色散补偿及光纤环形镜的工作原理进行了理论分析和仿真验证,取得了系统在2.5Gbit/s和10Gbit/s下Q参量和眼图的仿真数据,分别找出了两个信号速率下的系统最佳输入功率。结果表明,系统在2.5Gbit/s下的最佳输入功率为13dBm,此时Q参量达到了172.88;系统在10Gbit/s下的最佳输入功率为6dBm,其相应Q参量为45.96。这一结果对实际应用中光纤通信系统的色散补偿是有帮助的。     

光DQPSK调制在不同色散补偿系统中的性能

分析了光非归零-差分正交相移键控(NRZ-DQPSK)、33%归零-差分正交相移键控(33%RZ-DQPSK)和载波抑制归零-差分正交相移键控(CSRZ-DQPSK)三种调制格式的频域特性。并数字仿真了40Gbit/s的单信道光纤系统中三种调制格式在对色散(CD)进行后补偿、预补偿和对称补偿等三种补偿方式及考虑偏振模色散(PMD)和非线性效应情况下的传输性能。仿真结果表明,33%RZ-DQPSK对自相位调制(SPM)有最好的容忍度,但缓解PMD和CD的能力较弱;CSRZ-DQPSK在色散后补偿方式中对PMD和非线性效应具有最好的抑制能力。     

光子晶体光纤在CATV系统色散补偿中的应用

介绍了一种利用光子晶体光纤(PCF)作为宽带色散补偿的直接幅度调制残留边带(AM-VSB)有线电视传输系统.测试表明,与未加补偿的外调制方式相比,该系统具有更高的载噪比(CNR)、更优的复合二阶失真(CSO)和复合三阶差拍性能(CTB).将PCF用作色散补偿,可广泛应用于宽带高速长距离光纤通信领域.     

光纤通信系统中的可调谐色散补偿技术

对于高比特率的光纤通信系统,由温度或功率变化导致的色散波动高于系统的色散容限。因此,色散补偿单元必须具备动态可调谐功能才能适应下一代光通信网络发展的需要。本文介绍了几种动态可调谐补偿技术的基本原理性能特点及其国内外研究情况,其中包括啁啾光纤光栅法、虚像相位阵列法、G-T干涉仪法、阵列光纤光栅法和平面光波导法,并且简要讨论了可调谐色散补偿技术今后的发展方向。     

Dispersion compensation for optical fiber systems

Much of the currently embedded optical fiber was originally designed for light with a wavelength of 1.3 microns. If this fiber is to be used with tomorrow's optically amplified, high-speed, long span-length lightwave system operating at 1.5 microns, the chromatic dispersion in the fiber must be compensated. Dispersion compensation will be required in long-haul l0 Gb/s systems using conventional fiber. Many compensation techniques have been demonstrated and they exhibit a variety of different and often complimentary properties. Transmitter compensation techniques are the most easily implemented but provide a limited amount of compensation. The most commercially advanced technique is negative dispersion fiber. Chirped Bragg gratings are advancing rapidly, but will always be hampered by their narrow bandwidth. The adoption of any particular technique for use in a high-speed network will depend on the constraints imposed by the, as yet, undefined network architecture     

Density-matrix-formalism based scheme for polarization mode dispersion monitoring and compensation in optical fiber communication systems

We propose a density-matrix-formalism based scheme to study polarization mode dispersion (PMD) monitoring and compensation in optical fiber communication systems. Compared to traditional monitoring and compensation schemes based on the PMD vector in the Stokes space, the scheme we proposed requires no auxiliary matrices and can be handily extended to any higher-dimensional modal space, which is advantageous in mode-division multiplexing (MDM) systems. A 28 GBaud polarization division multiplexing quadrature phase-shift keying (PDM-QPSK) coherent simulation system is built to demonstrate that our scheme can implement the monitoring and compensation of 170 ps large differential-group-delay (DGD) that far exceeds the typical DGDs in practical optical communication systems. The results verify the effectiveness of the density-matrix-formalism based scheme in PMD monitoring and compensation, thus pave the way for further applications of the scheme in more general MDM optical communication systems.     

光传输系统中色散补偿问题的探讨

文章通过对光纤色散的产生及其对传输系统影响的介绍,引出了色散补偿技术.在多种色散补偿方法中,侧重探讨了应用比较普遍的色散补偿光纤(DCF)技术,并在此基础上,联系实际工程,具体阐述了光纤色散补偿模块大小在工程中如何计算、如何配备、如何放置等,获得了一些对实际色散补偿系统有参考价值的结论.     

Performance of alternate-block-inversion modulation format in optical communication systems with no dispersion compensation

Phase-shaped binary transmission (PSBT) is known to be an attractive modulation format in system with no inline dispersion compensation because of its resilience to chromatic dispersion. We show that the phased amplitude-shift signaling alternate-block-inversion (PASS-ABI) modulation format has a more compact spectrum and higher dispersion tolerance than PSBT while requiring similar transmitter complexity.     

光脉冲色散展宽的光纤光栅透射补偿

分析讨论了利用变迹均匀光纤光栅的透射色散对光纤中传输的脉冲色散展宽进行压缩补偿。给出了啁啾高斯脉冲的补偿原理,计算了相关的曲线和光纤光栅的相应参数。通过选择光纤光栅的不同参数,可以使色散展宽的高斯脉冲经光栅后几乎完全恢复原状或受到进一步压缩。     

八角格子色散补偿光纤

为了消除光纤通信系统中色散,采用各向异性完全匹配层和全矢量有限元方法,进行了理论分析和实验验证,设计了一种基于八角格子晶体的同轴双芯色散补偿光子晶体光纤;得到了该色散补偿光纤的传输特性如基模有效折射率、色散、损耗和非线性系数方面的数据,并分析了光纤波导色散与色散补偿光纤结构参量之间的关系。结果表明,所设计的光纤在200nm的负色散范围内,拥有负色散值(在波长为1.55m处有最低负色散值-1500 ps/(nmkm)),同时在E+S+C波段有较低的限制损耗(小于3.3dB/km);非线性效应也得到显著抑制。     

Performance degradation induced by polarization-dependent loss in optical fiber transmission systems with and without polarization-mode dispersion

The performance degradation caused by polarization-dependent loss (PDL) in optical fiber transmission systems in both the absence and presence of polarization-mode dispersion (PMD) is studied. First a simple theory is given to show how PDL affects the system performance and then extensive simulation results are presented. We show that PDL causes a much larger fluctuation of optical-signal-to-orthogonal-noise ratio (OSNR/sub ort/) than that of optical-signal-to-parallel-noise ratio (OSNR/sub par/), but OSNR/sub par/ has a much larger impact on the system performance than OSNR/sub ort/. We find that when there is no PMD, the system performance degradation induced by PDL can be effectively reduced by suppressing OSNR/sub par/ fluctuation. However, the presence of PMD in the system could significantly reduce the efficiency of the PDL mitigation technique, especially the mitigation technique that suppresses the OSNR/sub par/ fluctuation.     

电子色散补偿技术在高速光传输系统中的应用

电子色散补偿(EDC)技术作为一种新的光纤色散补偿技术正在逐步进入实用化阶段.文章介绍和分析了EDC的一般电路结构和工作原理,并通过对10 Gbit/s光传输系统的测试,和对测试数据的分析,验证了在10 Gbit/s光传输系统中EDC的补偿性能.     

OFDM在长距离光传输系统色散补偿中的应用

为了降低光纤长距离传输中电域色散补偿(EDC,Electronic Dispersion Compensation)的实现复杂度,采用正交频分复用技术(OFDM,Orthogonal Frequency Division Multiplexing)与光单边带调制(OSSB,Optical Single Sideband),可有效实现光纤的色散补偿。文章介绍了基于光直接检测(DD,Direct-Detection)的OFDM系统,重点对系统色散补偿的实现进行了具体的数学分析,并进行了数字仿真,就系统误码率(BER)与传统光传输系统(NRZ,Non-Return-to-Zero)进行了比较。结果表明,较传统光传输中电域色散补偿,基于光直接检测的OFDM系统色散补偿实现简单,系统复杂度降低,同时也提高了系统性能。     

光纤通信系统新码型用于多信道PMD补偿的研究

根据多信道偏振模色散(PMD)的最坏信道补偿方案,以粒子群优化(PSO)算法作为多信道PMD补偿算法,将一些典型的新型调制格式用于多信道PMD补偿,并以两信道PMD补偿系统为例进行了数值模拟,在补偿最坏信道的同时,保障了其他信道的性能,取得了很好的补偿效果.     

Robustness analysis of O-FDE algorithm for dispersion compensation in coherent fiber optical communications

The overlapping frequency domain equalization(O-FDE) in digital signal processing(DSP) is frequently employed to provide dispersion compensation in long-distance coherent fiber optical communications. However, the change in overlapping symbol length that occurs during the processing of the O-FDE algorithm will typically be influenced by the decision and zero filling of the last subblock, which is harmful to the robustness of the O-FDE algorithm. In this study, with a thorough robustness analysis...     

Fourth-order dispersion compensation for 250-fs pulse transmissionover 139-km optical fiber

Record distance transmission of 250-fs pulses over 139-km optical fiber at 6-GHz repetition is realized by compensating chromatic dispersion up to fourth-order using a novel approach. The link is designed combining 108.5-km standard single-mode fiber (SMF), 17.5-km dispersion-shifted fiber, and 13-km negative-slope dispersion-compensating fiber to achieve both zero total chromatic dispersion and slope at the 1.55-μm carrier. Fourth-order pulse dispersion caused by the fiber dispersion curvature around 1.55 μm is then suppressed by adding the quadratic phase of opposite sign from excess SMF to produce 503-fs output. However, both higher quality and shorter 390-fs output is achieved after applying 6-GHz electrooptic phase modulation (3.5 π O-peak) to prestretched pulses and adding a further 50-m SMF to the link     

Performance evaluation of optical fiber transmission systems

A method is presented for evaluating of error probability for optical-fiber communication systems in the present of intersymbol interference and additive noise. It is based on deriving a best approximation, in a minimax sense, for the cumulative distribution function of the additive noise. The method takes into account the avalanche photodetector's non-Gaussian shot noise statistics. The additive noise is also not constrained to be Gaussian. Examples are presented for comparison to previously published techniques     

Performance of MSE configured PLC optical equalizers for chromatic dispersion compensation

In this letter, we propose a mean square error (MSE) strategy to control a planar lightwave circuit (PLC) optical equalizer. We show by simulation that MSE is a suitable criterion to exploit the PLC programmability for realizing an adaptive optical equalizer. When controlled through the MSE criterion, a PLC equalizer for chromatic dispersion compensation performs better than with other control strategies and turns out to be effective even with few component elements.