集成光学声光光通道监测仪的研究

在集成声光可调谐滤波器(IAOTF)的基础上,提出了一种新型的集成光学波导型声光光通道监测仪(OCM).介绍了该OCM的工作原理及其基本结构,对它的插入损耗、响应时间、波长范围、波长分辨率和波长精度等性能指标进行了分析与计算,并对制成的集成光学声光OCM进行了实验研究.理论分析和实验结果表明,该OCM能够对密集波分复用(DWDM)系统多路光信道的工作波长和功率同时进行监测,其插入损耗小于3 dB,响应时间小于7μs,波长监测范嗣达174 nm,波长分辨率可达0.3 nm、波长精度可达±30 pm.     

ULH及WDM技术发展

一、概述随着业务量的提高,DWDM系统在我国骨干网和省二级骨干传送网的网络上得到了广泛的应用,基于10Gbit/s和2.5Gbit/s的DWDM系统已经成为基本的传送平台。在东部等业务量大的发达地区使用的是基于10Gbit/s的DWDM传送平台,目前使用C波段,波长间隔为100GHz,可升级为40波系统。     

外调制光发射模块

介绍2.5Gb/s外调制DWDM光发射模块设计及性能测试情况.文中LiNbO3外调制光发射模块用于32波长(100GHz间隔)的DWDM传输,可传输640km.该外调制模块包括控制模块和调制模块,它同其他SDH、DWDM光模块相比,在具有光功率监测、光功率告警和温度告警功能的同时,增加了激光器驱动电流监测、制冷电流监测、激光器管芯温度监测、波长控制功能等.外调制模块比其它方式的光发射模块具有色散性能好、传送距离远(与EDFA配合)等优点.外调制模块进行了温度实验,模块波长控制能力和光功率控制能力均达到传输系统要求,并且通过使用EDFA进行了400km、680km传输,获得了满意的结果.     

基于平板光波导任意带宽比的新型非对称交错滤波器

为了提高目前光纤通信系统的10 Gbit/s和40 Gbit/s混合系统的传输效率,提出了一种新型的器件结构以实现基于平面光波导的不等带宽交错滤波器。该结构结合光学微环与马赫曾德尔干涉仪结构,通过控制相关关键参数,实现了任意带宽比的光学交错滤波器,给出了带宽比为12的非对称交错滤波器设计实例。仿真结果表明,设计的交错滤波器在信道间隔为100 GHz的系统中给传输速率为10 Gbit/s和40 Gbit/s的两个信道分别分配了32.85 GHz和67.15 GHz的带宽,从而解决了传输速率为40 Gbit/s的信道带宽不足的问题。在此基础上通过分析器件中各双模干涉仪的光功率分配比对输出谱带宽比的影响,给出了在相同信道间隔条件下不同带宽比的非对称交错滤波器的设计实例。     

WA-7000DWDM高精度多路波长计

密集型波分复用通信(DWDM)技术在普通光纤通信系统中,可以提供无与伦比的宽带波段特性,并以极快的速度在发展.目前,通道间隔为100 GHz(约0.8nm)的DWDM系统已达到实用化水平.某生产DWDM系统的公司宣布已研制了通道间隔为50 GHz的系统.测量绝对波长的各种主要参数用的实验装置非常重要,它是准确评价DWDM系统特性的关键装置.     

多信道IM—DD密集波分复用光纤传输系统中的交叉相位调制效应

本文研究了交叉相位调制（XPM）对DWDM数字基带主干传输网性的影响,建立了表征XPM效应对任意调制信号在色散信道中传输的指标损伤的等效系统函数模型,并据此推导出了不同系统参数条件下（基带信号速率,波长信道间隔,复用信道数）计算XPM导致和系统光功率代价的计算公式,通过数值模拟计算证明了在基带信号速率高（＞2.5Gbit/s),波长信道间隔窄（－1nm),复用信道数多（＞8）的条件下XPM效应将成为限制系统性能的主要非线性因素。     

基于半导体光放大器频移的色散监测方法研究

利用半导体光放大器产生的频移效应监测单信道传输速率40 Gbit/s、CSRZ的高速光纤通信系统的残余色散.通过仔细选择光纤光栅滤波器的带宽和中心波长,可以实现色散监测系统性能的优化.动态色散监测系统的色散监测范围为±60 ps/nm,监测精度优于5 ps/nm,能够满足单信道速率为40 Gbit/s的CSRZ系统动态色散监测的要求.     

1.6 Tbit/s(40×40 Gbit/s)光通信传输系统

在国家自然科学基金网(NSFCNet)上已实现由400 km×10 Gbit/s传输链路直接升级的一路400 km×40 Gbit/s光传输实验的基础上,采用自行研制的40×40 Gbit/s载波抑制归零(CS-RZ)码多波长光发送源,进行了160 km的1.6 Tbit/s(40×40 Gbit/s)波分复用(WDM)光传输实验。实验结果表明,对于常规中短距离10 Gbit/s传输链路可以直接升级至40 Gbit/s。但是由于40 Gbit/s传输系统的色散容限小于60 ps/nm,而且传输光纤与色散补偿模块的色散斜率不匹配,要实现40通道40 Gbit/s的传输,必须对40个信道分别进行精细的色散补偿。这也说明,对于宽带的40 Gbit/s多波长系统,有必要优化设计或更新传输链路。     

基于Michelson--三镜G-T腔型不等带宽Interleaver的研究

通过分析三镜G-T腔的非线性相位性质,提出用等间隔三镜G-T腔代替Michelson干涉仪的一个全反射镜,构成不等带宽Interleaver。该器件将50GHz信道间隔的输入信号分离成100GHz信道间隔的不等带宽奇偶两路输出信号,可分别用于40Gb/s和10Gb/s传输,信道隔离度大于30dB。并经过计算机优化,得出所有满足DWDM系统以上要求的各反射镜的反射率。     

G.655光纤DWDM系统的DCF色散补偿方案比较

研究了NRZ-DPSK和NRZ-DQPSK G.655光纤40Gb/s DWDM通信系统中预补偿和逐段补偿两种色散补偿方案.通过仿真对比了这两种方案的色散性能和非线性性能,得出预补偿方案优于逐段补偿方案.在未来50GHz通道间隔40Gb/s DWDM系统中,采用预补偿能获得更好的传输性能.     

Key technologies for terabit/second WDM systems with high spectralefficiency of over 1 bit/s/Hz

To fully utilize a limited gain bandwidth of about 35 nm (4.4 THz) in an erbium-doped fiber amplifier, an increase in signal spectral efficiency is required. In this paper, we investigate the key technologies to achieve terabit/second wavelength-division multiplexing (WDM) systems with over 1 bit/s/Hz spectral efficiency. Optical duobinary signals, which have narrower optical spectra than conventional intensity modulation signals, were applied to such dense WDM systems. The measured minimum channel spacing for 20-Gbit/s optical duobinary signals was 32 GHz and a spectral efficiency of over 0.6 bit/s/Hz was reached. By using polarization interleave multiplexing, spectral efficiency was expected to reach 1.2 bit/s/Hz in an ideal case with no polarization dependencies along the transmission lines. In such ultradense WDM systems with narrower channel spacing, stabilizing the wavelengths of laser diodes is an important issue for achieving stable operation over long periods. To do this, we developed a simple and flexible wavelength stabilization system which uses a multiwavelength meter. The wavelengths for 116 channels with 35-GHz spacing were stabilized within ±150 MHz. The stabilization system is applicable to ultradense WDM signals with a spectral efficiency of over 1 bit/s/Hz by employing wavelength interleave multiplexing and an optical selector switch. On the basis of these investigations, we demonstrated a 2.6-Tbit/s (20 Gbit/s×132 channels) WDM transmission by using optical duobinary signals. In addition, 1.28-Tbit/s (20 Gbit/s×64 channels) WDM transmission with a high spectral efficiency of 1 bit/s/Hz was achieved by using polarization interleave multiplexing     

Comparison of system performance at 50, 62.5 and 100 GHz channel spacing over transoceanic distances at 40 Gbit/s channel rate using RZ-DPSK

Assuming RZ-DPSK format at 40 Gbit/s channel rate, the impact on the Q-factor of a variable channel spacing has been evaluated in five WDM experiments conducted in a recirculating loop over transoceanic distances. A degradation of the Q-factor by nearly 3 dB is observed when the channel spacing is reduced from 100 to 50 GHz     

Experimental evaluation of TeraLight/sup TM/ resistance to cross-nonlinear effects for channel spacings down to 50 GHz

An investigation is presented into the impact of cross-nonlinear effects over TeraLight/sup TM/ fibre through an analysis of a 400 km-long 32/spl times/10 Gbit/s WDM transmission with channel spacing of 100 and 50 GHz, span loss of 28 dB and optimised dispersion management.     

Simple and spectrally-efficient design of high capacity hybrid WDM/TDM-PON with improved receiver sensitivity

A simple design of hybrid wavelength division multiplexed/time division multiplexed passive optical network （WDM/ TDM-PON） is demonstrated for the high capacity next generation access （NGA） network, having advantages of both WDM and TDM based PON techniques. A 10 Gbit/s differential quadrature phase shift keying （DQPSK） data signal is used at optical line terminal （OLT） for downstream, whereas a 2.5 Gbit/s inverse return-to-zero （IRZ） data signal with high extinction ratio is used for upstream signal by intensity re-modulation of downstream signal, no additional laser is used at optical network unit （ONU）. Simulation results verify that aggregated 100 Gbit/s downstream transmissions of 10 DQPSK channels and aggregated 25 Gbit/s upstream transmission of 10 IRZ channels, using spectrally-efficient 50 GHz channel spacing, can be successfully achieved over a distance of 20 km with less than 1 dB transmission power penalties and improved receiver sensitivity.     

A novel non-uniform spacing coherent heterodyne WDM system with high channel efficiency

A novel non-uniform spacing coherent heterodyne wavelength division multiplexing (WDM) system is proposed, analyzed and investigated in this paper. High channel efficiency is realized by reducing the average channel space to half the value of the traditional uniform spacing WDM systems. Simulation shows that the proposed scheme exhibits excellent laser line width toleration of 10 MHz and channel space deviation toleration of ± $40%. Experiment setup of 2.5 Gbit/s heterodyne WDM transmission including differential phase shift keying (DPSK) and non-return-to-zero (NRZ) channels is established to investigate the scheme.     

1.6 Tbit/s (40 × 42.7 Gbit/s) WDM transmission over 2400 kmof fibre with 100 km dispersion-managed spans

Transmission of 40 × 42.7 Gbit/s WDM channels is demonstrated over 2400 km of fibre with 100 km amplifier spacing and 100 GHz channel spacing. Dispersion-managed fibre spans, carrier-suppressed return-to-zero modulation format and hybrid Raman/erbium-doped fibre inline amplifiers were employed to achieve a record 40 Gbit/s, WDM transmission distance with 100 km terrestrial span lengths     

Transmission of 622 Mbit/s spectrum-sliced WDM channel over 60 kmof nondispersion-shifted fibre at 1550 nm

The transmission of a spectrum-sliced WDM channel at 622 Mbit/s over 60 km of nondispersion-shifted fibre using an optical bandwidth of only 0.23 nm is reported. This is the highest single channel bit rate-length product (40 Gbit/s·km) and smallest channel bandwidth reported to date for spectrum-sliced WDM systems. The bit error rate performance is theoretically predicted and experimentally confirmed and limits on the bit rate-length products of spectrum-sliced WDM channels using nondispersion-shifted fibre in the 1550 nm window are given     

Time-domain interleaving technique for wavelength-swept light based super dense WDM transmitter

Proposed is a time-domain interleaving technique for increasing the transmission rate of a previously reported wavelength-swept light based WDM transmitter. With this technique, the bit rate of each channel can be multiplied without increasing the repetition frequency of the wavelength sweep and without severe inter-channel crosstalk. A four-channel 2.5 Gbit/s super dense WDM transmission experiment with two interleaved 1.25 Gbit/s data streams is demonstrated.     

Coherent Equalization and POLMUX-RZ-DQPSK for Robust 100-GE Transmission

We discuss the use of a coherent digital receiver for the compensation of linear transmission impairments and polarization demultiplexing in a transmission system compatible with a future 100-Gb/s Ethernet standard. We present experimental results on the transmission performance of 111 Gbit/s POLMUX-RZ-DQPSK. For a dense WDM setup with channels carrying 111 Gbit/s with a 50 GHz channel spacing (2.0 bits/s/Hz), we show the feasibility of 2375 km transmission. This is enabled through coherent detection which results in excellent noise performance, and subsequent electronic equalization which provides the high tolerance to polarization mode dispersion and chromatic dispersion (CD). Furthermore, we discuss the impact of sampling and digital signal processing with either 1 or 2 samples/bit. We show that when combined with low-pass electrical filtering, 1 sample/bit signal processing is sufficient to obtain a large tolerance towards CD. The proposed modulation and detection techniques enable 111 Gbit/s transmission that is directly compatible with the existing 10 Gbit/s infrastructure.