Optical Label-Based Cost-Effective DWDM Optical Network Performance Monitoring Using Low-Bandwidth PD with Novel SRS Mitigation DSP

Large-scale dense wavelength division multiplexing(DWDM)multi-channel performance monitoring is one of the indispensable technologies for the flexible optical networks.The existing Labelbased monitoring scheme requires expensive optical demultiplexing components/equipment to avoid the influence of stimulated Raman scattering(SRS),which is not only costly and bulky,but also could not monitor the wavelength channels simultaneously.In this paper,a low-cost,high-accuracy monitoring scheme based on Optical Label Method is proposed for DWDM networks,where the optical channel power and node identification(ID),as the main monitoring targets that both can indicate or evaluate the channel connection status,could be efficiently monitored.In the scheme,a novel digital signal processing(DSP)method of SRS mitigation is proposed and demonstrated,and an asynchronous code-division multiple access(A-CDMA)based digital label encoding and decoding method is adopted to distinguish the node ID so that channel initial added node can be accurately verified,thereby wavelength connection status can be reliably monitored by combining the channel power and node ID information.The simulation results show that each wavelength channel power and node ID can be accurately monitored only by low bandwidth photoelectric detector(PD)under the condition of 80 wavelengths and 10 spans at C-band.

A Method of Peak Detecting for Nanosecond Pulse in Optical Performance Monitoring System

In optical performance monitoring system,the analog to digital converter is needed to detect the peak of nanosecond pulse and get the signal envelope.A scheme based on a designed anti-aliasing filter and analog to digital converter is proposed to broaden the nanosecond pulse and make it easier for the analog to digital converter to catch the peak of the nanosecond pulse.The experimental results demonstrate that,with the proposed scheme,the optical performance system needs less time to get the recovered eye-diagram of high speed optical data signal,and is robust to phase mismatch in the analog to digital converter circuit.

A Novel Outage Capacity Objective Function for Optimal Performance Monitoring and Predictive Fault Detection in Hybrid Free-Space Optical and RF Wireless Networks

This study develops an optimal performance monitoring metric for a hybrid free space optical and radio wireless network, the Outage Capacity Objective Function. The objective function—the dependence of hybrid channel outage capacity upon the error rate, jointly quantifies the effects of atmospheric optical impairments on the performance of the free space optical segment as well as the effect of RF channel impairments on the radio frequency segment. The objective function is developed from the basic information-theoretic capacity of the optical and radio channels using the gamma-gamma model for optical fading and Ricean statistics for the radio channel fading. A simulation is performed by using the hybrid network. The objective function is shown to provide significantly improved sensitivity to degrading performance trends and supports of proactive link failure prediction and mitigation when compared to current thresholding techniques for signal quality metrics.

Multiple-impairment monitoring for optical duobinary system based on delay-tap asynchronous sampling

A technique using artificial neural networks trained with parameters derived from delay tap plots for optical performance monitoring in 40 Gbit/s duobinary system is demonstrated. Firstly, the optical signal is delay tap sampled to obtain two-dimensional histogram, known as delay tap plots. Secondly, the features of delay tap plots are extracted to train the feed forward, three-layer preceptor structure artificial neural networks. Finally, the outputs of trained neural network are used to monitor optical duobinary signal impairments. Simulation of optical signal noise ratio （ OSNR）, chromatic dispersion （CD）, and differential group delay （DGD） monitoring in 40 Gbit/s optical duo- binary system is presented. The proposed monitoring scheme can accurately identify simultaneous impairments without requiring synchronous sampling or data clock recovery. The proposed technique is simple, cost-effective and suitable for in-service distributed OPM.

Joint modulation format identification and OSNR monitoring based on Stokes vector distribution features for digital coherent optical receivers

For joint modulation format identification(MFI)and optical signal-to-noise ratio(OSNR)monitoring,a simple and intelligent optical communication performance monitoring method is proposed,and the feasibility is demonstrated by digital coherent optical communication experiments.The experiment results show that for all modulation formats,including 28 GBaud polarization division multiplexing(PDM)QPSK/8-QAM/16-QAM/64-QAM,100%MFI accuracies are achieved even at OSNR values lower than the corresponding theoretical 20%forward error correction limit,as well as the high accuracies for OSNR monitoring.Furthermore,the proposed scheme has a reasonable monitoring level when chromatic dispersion and fiber nonlinear effects are varied.

Toward Low-Cost Flexible Intelligent OAM in Optical Fiber Communication Networks

Low-cost,flexible and intelligent optical performance monitoring and management is a key enabling technology for network quality guarantee,especially in the era of explosive growth of communication capacity and network scale.However,to the best of our knowledge,it is extremely challenging to implement real-time performance monitoring and operations,administration and maintenance(OAM) in a highly complex dynamic network.In this paper,we propose an innovative optical identification(OID) scheme that can realize both performance monitoring and some advanced OAM sub-functions.The basic concepts,applications,challenges and evolution directions of this OID tool are also discussed.

基于机器学习的光网络监测与优化方法

近年来,许多新型调制和复用技术以及动态网络概念被提出,以适应不断提高的网络带宽和质量需求。网络控制平台向系统化、智能化趋势发展,要求网络管理者不断监测网络各项参数,时刻优化网络状态。然而,大范围部署额外的监测设备获取参数信息从成本控制的角度缺乏可行性,利用已知数据与特殊算法进行网络性能监测和优化是更优的选择。机器学习方法因为其足够准确和高效逐渐被学术界采纳用于完成上述任务。文章梳理了在光网络监测与优化任务中使用机器学习算法的不同应用场景,综述了该领域的研究成果,并提出了现存的基于机器学习的光网络监测与优化方法存在的问题及可能的进一步研究的方向。基于机器学习的光学性能监测包括光学损伤辨别、信道质量评估以及通道功率预测,基于机器学习的网络配置优化方法包括强化学习优化通道功率。进一步研究方向可以考虑加强与运营商的合作,使用真实的现场数据,不断获取数据动态训练模型,并使用迁移学习和数据增强等技术,以保证算法的鲁棒性与泛化能力。

基于全光网络的光纤通信传送网性能监测技术

文章针对全光网络中光纤通信传送网的性能监测问题,提出一种基于光电检测、信号处理、大数据分析以及机器学习等技术的智能监测系统。该系统采用模块化设计,可实现光信号质量监测、网络性能分析、故障诊断与定位等功能。通过实验验证,该系统在实时性、准确性、可靠性等方面均达到预期目标,为全光网络的智能化管理和优化控制提供了有力支撑。

光插分复用器中基于Athermal-AWG的OPM系统分析

基于衍射型OPM(Optical Power Monitor)能够在设定的波长范围内对不同波长的光信号进行实时采样,其稳定性好并能快速测量。采用阵列波导光栅对波分复用信号进行分解复用,不同波长的光信号分别经过相应的分束器,探测器阵列对各路通道的光进行探测。探测器阵列能够探测出各波长的光功率、光电流以及插入损耗,计算出耦合后的响应度。分析响应度和插入损耗与波长的关系,得出此结构系统能够应用在光差分复用器中。

基于深度神经网络的IMDD系统光性能监测技术

在先进高速光纤通信系统中,密集波分复用技术的引入使得信号频谱间隔越来越窄,传统的带外光信噪比(OSNR)监测技术不再准确,需要进一步研究低成本的带内OSNR监测方案。文章提出了一种基于深度神经网络(DNN)的直调直检(IMDD)系统链路OSNR监测方案,采用550 000组数据集训练的5层DNN结构,在5~15 dB范围内,成功估计出了2 GBaud开关键控(OOK)信号的OSNR,平均绝对误差(MAE)小于0.8 dB。文章所提方案有望作为一种高效低成本方案,助力光网络智能运维。

基于高空间分辨率BOTDA的土体沉降监测研究

地面沉降因其不易被察觉、成灾后果严重,一直都是当今危害较大的一种地质灾害问题.为了能够对地面沉降灾害做出有效预防,地面发生沉降时对土体进行位移监测尤为重要.分布式光纤传感技术因其可实现高灵敏度的分布式监测而成为获取土体沉降位移信息的手段之一.在充分考虑直埋式应变传感光纤和周围土体沉降协调的基础上,运用厘米级高空间分辨率布里渊光时域分析(Brillouin optical time domain analysis,BOTDA)技术测量土体发生沉降时实验段光纤的应变分布,根据应变-位移计算模型将应变测值转换成位移信息,从而实现对土体沉降位移的测量,并与土体实际沉降位移进行了对比分析.实验结果表明,在光纤与土体耦合良好的阶段,沉降位移的实验测量结果与土体实际沉降位移之间符合较好;在光纤上布设地锚可以提高光纤与土体的耦合性能,进而获得更好的沉降监测效果;实验得到的纤-土沉降耦合变形程度划分标准可以用于定量评价沉降过程中光纤与土体的耦合程度.

Chromatic dispersion monitoring using semiconductor optical amplifier

An all-optical real-time chromatic dispersion （CD） monitoring technique is proposed and demonstrated for 40Gbit/s differential phase-shifts keying （DPSK） signal, utilizing the cross modulation effects of semicon- ductor optical amplifier （SOA）. The optical power of the output spectral components, which is from the probe＇s frequency up to the signal bandwidth, is used for CD monitoring. This technique provides a wide monitoring range with large variation scale. The impacts of the polarization mode dispersion （PMD） and the optical signal-to-noise ratio （OSNR） on the CD monitoring results are theoretically analyzed and then experimentally investigated, showing that they have slight influence on the monitoring results within a certain range. Furthermore, simulated results for quadrature phase shift keying （QPSK） signal at 80 Gbit/s are also demonstrated, indicating that this technique is suitable for advanced modulated format as well.

全光网中光码流性能的整体监控

波分复用(WDM)多粒度交换可重构全光网是当前光通信网发展的方向,该文构造了一种实际试验网,提出了一种"眼图法"对网中数字光信号进行全面监控的方法,并在自建WDM多粒度交换可重构全光网试验床上进行了演示,结果显示在网络重构等各种条件下均可对网中各波长通道数字信号的信噪比、定时抖动、功率、误码率等进行实时监测控制,该方法对光信号的协议和速率透明且能对各种光性能劣化进行鉴别。

分布式光纤井温法产液剖面解释方法研究

为了解生产井段产出或吸入流体的性质和流量,对油井生产状况和油层生产性质作出评价,应用分布式光纤温度传感系统进行油气田开发动态监测。分布式光纤温度系统是一种用于实时测量空间温度场分布的传感系统,它通过沿整个完井长度连续性采集温度资料来监测油气田开发动态。介绍了分布式光纤温度传感系统测量原理和井下测量方式,研究了生产井内温度分布特性及热交换模型。根据井内流体温度和地层温度资料的对比分析,提出了相应的半定量解释处理方法。对现场实测资料进行了处理解释,结果与实际生产情况相符,表明所提出的解释方法可行。

光传送网的性能监测方案

在简要回顾传统性能监测方案的基础上,引入了插入型(Intrusive )和非插入型(Non-intru-sive)在线性能监测的分类方式,着重阐述了基于模拟量监测的非插入型光性能监测方案。

分布式光纤测温技术在油田开发中的发展潜力

分布式光纤测温技术(DTS)是一种实时连续较为准确测量温度剖面的新兴技术。从分布式光纤测温的基本原理和光纤安装方式、类型出发,介绍了分布式光纤测温技术在油田开发中的应用并说明了实施分布式光纤温度测试的选井标准,阐述了分布式光纤测温技术在监测油井动态生产信息方面与其它常规监测技术的优势并对其进行了经济评价。研究分析表明分布式光纤测温技术在油气井生产动态监测与优化和复杂油气藏的高效开发中具有巨大的潜力。

线性调频z变换在光采样光性能监测中的应用

研究采用异步降频光采样技术进行光性能监测的方法,通过软件同步算法对采样信号进行眼图重构和Q值监测.在软件同步算法中使用线性调频z变换(CZT)对离散傅里叶变换频谱进行局部细化,提高频谱分辨率,获取准确的眼图重构时间参数.仿真实验表明,CZT算法能够准确重构被监测光信号的眼图并测量Q值,在算法精度和稳定度方面都优于目前已有算法,且计算时间进一步降低40%.该方法快速、准确,能够很好地应用于光采样光性能监测系统.

高非线性光纤中并行交叉相位调制的偏振膜色散监测方法

利用信号光和插入的连续泵浦光之间产生的交叉相位调制（XPM）效应，提出了一种基于并联的XPM效应来监测光相位调制信号的一阶偏振模色散（PMD）的新技术。泵浦光的光谱会随着信号光中PMD和色散（CD）的变化而发生变化，所以导致泵浦光的光功率发生变化，在并联的一个支路中抑制PMD的影响，利用并联的两路同一波段泵浦光功率的差值来进行监测。仿真结果显示，新的技术可以实现对40 Gb/s非归零差分四相移相键控（NRZ-DQPSK）光信号从0～20 ps的监测。在20 ps的监测范围内，新技术的动态范围大于3 dB，可以用来进行准确的监测。对信号速率、色散、泵浦光功率和滤波器带宽对新技术的影响做了详细的研究。

基于OTDR的光路监测终端设计

针对目前光纤通信网络规模的不断扩大以及人们对光通信网可靠性的需求,该文研制了一种基于OTDR的光路监测终端。该装置由数据处理模块、光路监测模块、电源模块、人机交互模块等组成。数据处理模块由STM32F407芯片及其子系统组成;光路监测模块由OPM模块以及OTDR模块组成,OPM模块对光路性能参数进行监控,包括功率、波长等,用于发现光路故障,OTDR模块可检测到故障点与监测终端的距离;电源模块由开关电源模块与降压芯片组成,能将220 V交流电转换为5 V/3.3 V直流电,为CPU以及各模块提供电源;人机交互模块采用了0.96寸OLED和GPRS模块组成。软件基于轮询的方式,将监测模块采集的数据进行故障分析,定位故障点,将位置信息以短信方式发送给维护人员,并在OLED上显示光路故障告警信息。

植入式光纤传感器在隧道结构中的边界效应研究

为探究植入式光纤传感器与隧道衬砌的应变传递的边界效应,分别从理论、试验和现场应用3个方面进行研究,并在实际工程中进行了验证。构建了光纤在混凝土衬砌中的应变传递模型,进行光纤应变传递机制分析,计算了光纤应变传递效率,并与数值计算结果对比,验证了力学计算模型的准确性。使用钢筋混凝土梁模拟隧道的混凝土衬砌,在其表面植入分布式光纤,进行了2组试验。对试验梁进行分级加载并使用BOFDA技术对光纤进行测试。试验结果表明:植入式光纤传感器存在边界效应,结构两端为光纤的低效率应变传递区,不能完全传递试验梁的应变;试验梁中部为光纤的高效率应变传递区,能够完全传递试验梁的应变。基于以上研究成果,在北京市新机场线地铁暗挖隧道CRD工法区间,采用植入式工艺在隧道衬砌内布设了分布式光纤传感器,进行了工程应用研究。监测结果表明,边界效应对工程监测结果影响很小,分布埋入式光纤布设工艺是可行的。该研究可为分布式光纤技术在地下工程结构监测中的应用提供参考。