DM solitons in long-haul DWDM systems at 40 Gb/s with nonlinear interactions and PMD

The authors investigate for the first time how polarization mode dispersion and nonlinear interactions affect dense wavelength division multiplexing dispersion management-soliton long-haul transmission using Monte Carlo simulations. They also discuss how the system is affected by an increasing number of wavelength channels.     

40Gb/s DWDM系统不同码型传输性能的比较

采用Optisystem软件,对比分析了非归零码(NRZ)、归零码(RZ)、载波抑制归零码(CS-RZ)和载波抑制归零差分相移键控码(CSRZ-DPSK)四种码型在8×40Gb/s DWDM系统的传输性能。结果表明,CSRZ-DPSK码抗色度色散和PMD性能最优,CS-RZ码的OSNR容限最低。当入纤光功率适中、色散和色散斜率同时补偿时,CSRZ-DPSK码和CS-RZ码的最大传输距离超过2700km。     

Alternative modulation formats in N×40 Gb/s WDM standardfiber RZ-transmission systems

A comparison of carrier-suppressed return-to-zero (CSRZ) and single sideband return-to-zero (SSB-RZ) formats is made in an attempt to find the optimum modulation format for high bit rate optical transmission systems. Our results show that CSRZ is superior to return-to-zero (RZ) and SSB-RZ with respect to signal degradation due to Kerr nonlinearities and chromatic dispersion in wavelength division multiplexing (WDM) as well as in single-channel 40-Gb/s systems over standard single-mode fibers (SSMF). It is shown that CSRZ enables a maximum spectral efficiency of approximately 0.7 (b/s)/Hz in a N×40 Gb/s WDM system with equally polarized channels. Furthermore, the CSRZ format in N×40 Gb/s WDM systems shows no further signal degradation compared to single-channel transmission     

Bandwidth virtualization enables long-haul WDM transport of 40 Gb/s and 100 Gb/s services

This article describes how bandwidth virtualization can enable transmission of ultra-high bandwidth 40 Gb/s and 100 Gb/s services over existing optical transport networks independently of the underlying network infrastructure. An overview of the technology alternatives available to enable high-bandwidth service transport is provided, along with a discussion of the relative merits of different approaches. The authors describe how wavelength division multiplexing, using large- scale photonic integrated circuits combined with the use of a digital virtual concatenation mapping protocol, can be used to enable decoupling of 40 Gb/s and 100 Gb/s service provisioning from the underlying optical link engineering, thereby enabling bandwidth virtualization. Real-world implementation examples of bandwidth virtualization are provided, including 40 Gb/s service transmission over a 2000-km fiber link with 65 ps of peak PMD, a field trial of 40 Gb/s service transmission over an 8477-km trans-oceanic network, and finally a field trial of a pre-standard 100 gigabit Ethernet service transmission over a 4000-km terrestrial long-haul network.     

40Gb/s光纤传输系统中四种调制格式的性能比较

使用Opt i s ys t em软件,对40Gb/s单信道传输系统中非归零(NRZ)、归零(RZ)、光双二进制(ODB)、改进的光双二进制归零(MD-RZ)四种调制格式进行仿真。长距离传输后,MD-RZ的眼睛睁开度最大,Q值也很高,具有较好的色散容限和非线性容限,适合长距离传输。     

40Gb/s光通信系统不同码型传输性能分析

使用Optisystem仿真工具,对非归零(NRZ)、归零(RZ)、载波抑制归零(CS-RZ)和归零差分移相键控(RZ-DPSK)四种码型在40Gb/s单信道传输系统中的灵敏度、非线性效应和色散容忍度进行比较,并对标准单模光纤(G.652)中四种码型的单信道40Gb/s长距离传输进行了仿真,结果表明:CS-RZ具有更优的灵敏度和抗噪声能力,RZ-DPSK码具有更优的非线性容忍度.在较低入纤功率条件下,G.652光纤作为传输介质,CS-RZ系统的传输性能最优.     

应用于40Gb/s光传输系统新兴调制方式

阐述了双偏振正交相移键控(DP-QPSK)系统的调制编码和检测原理,详细描述关于DP-QPSK40Gb/s WDM系统结构和性能的最新研究进展,并将DP-QPSK与Duo-Binary、DPSK和DQPSK等几种调制编码方式进行了全面比较,展示了DP-QPSK作为一种新兴的调制方式,在400b/s系统研究领域具有很高的研究价值和广泛的应用前景.     

On the use of NRZ, RZ, and CSRZ modulation at 40 Gb/s with narrow DWDM channel spacing

The use of nonreturn-to-zero (NRZ), return-to-zero (RZ), and carrier-suppressed return-to-zero (CSRZ) modulation formats in an ultradense wavelength-division multiplexing (UDWDM) scenario at 40 Gb/s is investigated. The results of a simulative analysis on back-to-back setups are presented. Narrow optical filtering at the receiver and at the transmitter, as well as the orthogonal polarization launch of adjacent channels, is studied in order to improve spectral efficiency. We demonstrate that standard setups do not allow acceptable performances with 50-GHz channel spacing for all the considered modulation formats, while the use of a transmission optical filter may dramatically improve the performance of RZ and CSRZ modulation formats that become suitable for the use in UDWDM systems. We show that, due to the narrow transmission filtering, the RZ pulse becomes NRZ-like, and the CSRZ modulation is duobinary coded. Furthermore, we demonstrate that NRZ modulation does not benefit from the introduction of a transmission optical filter, while it takes advantage of the orthogonal polarization launch of adjacent channels, but its performance is still worse than the RZ and CSRZ performance in a UDWDM scenario.     

色散会否成为40Gb/s系统的杀手

尽管已经有了新型色散补偿光纤,但对色散控制的需求仍然可能继续扩大。     

Automatic compensation of polarization-mode dispersion for 40 Gb/s transmission systems

We present an automatic compensator that effectively mitigates signal distortion due to polarization-mode dispersion (PMD). Accurate compensation is achieved by utilizing a degree of polarization (DOP) monitor with a measurement uncertainty of better than 1% achieved by applying a self-dependent precalibration procedure. The compensation performance at 43 Gb/s was evaluated systematically with respect to both first- and second-order PMD by using a crystal-optical PMD emulator. The compensator extended the tolerable differential group-delay (DGD) limit from 8 to 28 ps, while maintaining the Q penalty below 1 dB. In terms of the average of a Maxwellian-distributed DGD, the PMD compensator enabled transmission for up to 8 ps, or about three times higher than the level tolerated in the uncompensated case. In addition to the compensation performance, we demonstrate successful operation, even for distorted signals with high chromatic dispersion. We believe this capability will be a key enabler for a combined operation with adaptive chromatic dispersion compensators.     

40 Gbit/s WDM系统在长途骨干网中的应用

随着业务的爆炸式增长,40 Gbit/s WDM(波分复用)系统已经在现有骨干网中大规模商用。文章分析了40 Gbit/s系统工程建设中的相关问题,包括40 Gbit/s系统的光纤选型、编码选择、40 Gbit/s系统中10 Gbit/s业务的解决方案、40 Gbit/s系统的OLP(光线路保护)和客户端解决方案。     

10Gb/s和40Gb/s RZ-DPSK电预失真系统中非线性效应的研究

通过仿真研究了10和40Gb/s RZ-DPSK电预失真(EPD)系统中的自相位调制(SPM)和交叉相位调制(XPM)等非线性效应。EPD系统中的非线性效应比光色散补偿(ODC)中的大,但在不同比特率下非线性效应不同。对800km标准单模光纤(SSMF)传输的仿真的结果表明:单信道传输时受到SPM影响,比特率为10Gb/s的EPD系统的非线性阈值比ODC系统的小6dBm以上,而当比特率为40Gb/s时的EPD系统非线性阈值只比ODC系统小2dBm。波分复用(WDM)系统中受到SPM和XPM的影响,比特率为10Gb/s的EPD系统的非线性阈值比ODC系统的小6dBm,而比特率为40Gb/s时的EPD系统非线性阈值比ODC系统的小2dBm。研究结果表明,当比特率升高时,EPD系统的非线性效应减弱。     

Performance of non-fibre based dispersion compensation for long-haul 10.7 Gbit/s DWDM transmission

Non-fibre based in-line dispersion compensation is employed to achieve long-haul transmission of 80 channels at 10.7 Gbit/s bit rate over 1200 km of LEAF fibre. Average system margins of more than 4 dB and small transmission are demonstrated. The additional penalty incurred by the periodic nature of the dispersion compensator is assessed.     

不同调制格式对400 Gb/s通信系统传输容量和距离的影响

单载波400 Gb/s传输是下一代通信系统的主要应用速率,为提高此速率通信在实际工程应用中的传输效率,理论分析了高速通信系统中不同调制方式与传输谱宽的关系,基于16阶正交幅度调制(16QAM)、16QAM/32QAM混传、32QAM、32QAM/64QAM混传和64QAM 5种不同调制格式,对400 Gb/s传输系统的...     

基于RSOA再调技术40Gb/s传输系统研究

下一代接入网的发展趋势是WDM-PON(波分复用无源光网络),基于反射式半导体光放大器(RSOA)再调制的无色ONU技术降低WDM-PON成本与结构简化,因而具有较强的市场潜力。DPSK具有恒功率特性且抗干扰性能显著,常优先选作系统调制方式。在不断追求高速率、大容量的时代,单信道40Gb/s的光传输系统的研究就极具有意义。利用OptiSystem软件,仿真了基于RSOA的40Gb/s传输系统,分析了RSOA的增益特性与系统性能,最后验证了DPSK在基于RSOA的高速PON中应用的可行性。     

Cost‐Effective Transition to 40 Gb/s Line Rate Using the Existing 10 Gb/s‐Based DWDM Infrastructure

In this paper, we propose and demonstrate a cost‐effective technique to upgrade the capacity of dense wavelength division multiplexing (DWDM) networks to a 40 Gb/s line rate using the existing 10 Gb/s‐based infrastructure. To accommodate 40 Gb/s over the link optimized for 10 Gb/s, we propose applying a combination of super‐FEC, carrier‐suppressed return‐to‐zero, and pre‐emphasis to the 40 Gb/s transponder. The transmission of 40 Gb/s DWDM channels over existing 10 Gb/s line‐rate long‐haul DWDM links, including 40×40 Gb/s transmission over KT's standard single‐mode fiber optimized for 10 Gb/s achieves successful results. The proposed upgrading technique allows the Q‐value margin for a 40 Gb/s line rate to be compatible with that of 10 Gb/s.     

Wavelength shift keying modulation up to 35 Gb/s with wavelength tone reuse to multiplex two 40 Gb/s DPSK signals

Fast optical frequency shift keying or wavelength shift keying (WSK) modulation offers advantageous features for applications in long haul communications and in optical labeling for packet routing. This includes simple demodulation by optical filtering and constant amplitude envelope providing tolerance to fiber nonlinear effects during transmission. In this paper we report on the generation of WSK signals up to 35 Gb/s with reuse of the wavelength tones for polarization multiplexing two independent 40 Gb/s DPSK signals. Transmission over a 50 km fiber link of the resultant three channel signal is also reported.