光通信中的光电子器件讲座第四讲 光通信中的波分复用技术及关键器件的原理和应用

通信业务的爆炸式发展，使得通信网络对传输容量要求急剧提高。WDM（wavelength divsion multiplexing）技术是增加系统容量的有效方法。文章介绍了光通信中波分复用技术的基本原理和特点以及波分复用技术中所用的关键器件－波分复用器／解复用器。     

波分复用器在光纤通信中的应用

在光纤通信领域中使用波分复用技术，可以极大地提高网络的传输容量及速率，是解决现代通信技术带宽危机的有效方法．本文介绍了波分复用（WDM）器件的特性，并以双路双向光纤通信为例说明应用WDM技术的优势．     

平场输入/输出蚀刻衍射光栅的设计

光通信中波分复用技术是解决通信网络瓶颈的有效手段，近年来得到很大发展。以平面波导波分复用器件为核心的密集波分复用技术已经得到成功商用。蚀刻衍射光栅是平面波导密集波分复用器件中很有发展潜力的一种。原有蚀刻衍射光栅采用罗兰圆设计，输入输出在圆弧曲线上由条形波导引出；而平场输入／输出的蚀刻衍射光栅在很多应用中可以省去制作输入输出波导，大大简化制作工艺，同时能够保持良好的线性色散和聚集效果。给出了平场输入和输出蚀刻衍射光栅的设计方法，并利用标量衍射理论对设计的结果进行模拟，验证了平场输出蚀刻衍射光栅具有很好的分波效果。     

光纤菲佐应变传感器的波分频分复用方法

将波分复用技术与空间频率复用技术相结合,提出了新的光纤菲佐应变传感器波分频分复用方法:在粗波分复用(CWDM)的不同波段实现具有不同腔长的光纤菲佐应变传感器的空间频率复用。描述了基于该方法的光纤菲佐应变传感器复用系统的结构、原理及实验结果,讨论了复用技术中可能产生的串扰的影响及其解决方法。实验结果表明,该方法大大提高了光纤菲佐应变传感器的复用能力,可复用40个以上的菲佐应变传感器,且其应变测量精度达±5με,可满足实际应用的要求。     

蚀刻衍射光栅波分复用器件的设计与模拟

近年来光通信飞速发展,波分复用技术(WDM)是满足要求的有效手段.密集波分复用技术已经得到成功商用,其扩展信息传输容量的能力也在不断增强.作为波分复用中最关键的器件,蚀刻衍射光栅(EDG)是平面波导密集波分复用器件中很有发展潜力的一种.本文分析了EDG器件的解复用原理,参量设计,工艺过程.文章最后,建立了一个光栅干涉的简单模型,对设计好的器件参量进行模场形状、谱响应、色散等光栅性能的模拟,得到基本的器件解复用特性,并加以分析.     

基于LED可见光波分复用的音频传输演示仪

利用LED高频率闪烁的响应特性,设计了一种基于LED可见光波分复用的音频传输演示仪。波分复用是让不同波长的可见光同时加载不同信号,通过同一信道传输信息的通信技术。本装置实现了可见光通信技术和波分复用技术的结合,可以大大提高可见光通信的效率。装置亦可用于课堂演示。     

波分复用串联的布里渊散射分布式光纤传感器

在一定分辨率和响应时间要求下，应用波分复用技术来串联布里渊散射分布式光纤传感器，解决了同时进行传感和通信存在的信号干扰.具体是采用波分复用来隔离传感光信号与通信光信号，同时应用光相干外差接收来分离传感与通信之间的电信号频谱.实现了两台布里渊散射分布式光纤传感器之间的串联，单台传感器的传感距离为25 km，串联后达到50 km.     

基于光强与吸收率非线性同步拟合的吸收光谱测量方法

针对高压环境吸收谱线加宽以及波分复用技术合波透射信号分析测试难题,提出利用非线性拟合方法对激光吸收光谱测量中激光强度与吸收光谱进行耦合求解.建立激光强度非线性变化与多谱线吸收拟合函数关系,解决了特殊环境下无法获取光谱基线的难题,实现了波分复用过程合波后光谱信号的分离与诊断.通过仿真验证该方法的可行性,分析计算了激光器特性和特征谱线位置等因素对拟合结果的影响.搭建实验台实现了1—10 atm变压力环境下6330—6337 cm~(-1)波段CO_2吸收光谱叠加信号的诊断分析,对气液两相脉冲爆轰过程中7185.6 cm~(-1)与7444.35 cm~(-1)波段波分复用光谱信号进行测试与拟合,无需分光设备实现了耦合光路分离和温度计算,研究结果对激光吸收光谱技术在高压环境以及燃烧环境下波分复用技术的发展具有重要意义.     

采用密集波分复用技术的光纤水听器阵列研究

利用密集波分复用和时分多路复用技术相结合的大规模阵列结构,以Mach-Zehnder干涉型光纤水听器为例,分析了采用相位产生载波技术的频分多路复用,提出了密集波分复用技术在干涉型光纤水听器阵列应用的新方法,给出了复用体系结构,并分析了其在工程上可行性.     

用于Si基RCE光电探测器SOR衬底的研制

随着波分复用技术的发展，共振腔增强（RCE）探测器由于具有波长选择特性和高和量子效率得到重视和发展。本文报道了采用智能剥离和溶胶－凝胶方法研制出一种可用于Si基RCE光电探测器SOR衬底。得到表面是单晶Si膜且具有高反向率的Si基片。设计和模拟了基于该衬底的SiGeRCE光电探测器，结果表明该结构可以大幅度提高Si基探测器的量子效率。     

Ultrafast and Wideband All-Optical Processing Technologies Towards Flexible Photonic Networks

Recent progress in ultrafast and wideband all-optical processing technologies to realize flexible and transparent optical time-division multiplexing (OTDM)/wavelength-division multiplexing (WDM) photonic networks is reviewed covering ultrafast OTDM technologies handling more than 100 Gbit/s per wavelength channel and wideband WDM technologies handling more than 1000 wavelength channels over the 200 nm range.     

Transmission Characteristics of Several Kinds of Filters for WDM Optical Networking

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A New 1×K Tunable Multi-wavelength Router and its Features

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A New 1×K Tunable Multi-wavelength Router and its Features

Tunable wavelength routers (TWRs) for multiple wavelength selection are key devices in dynamic wavelength-routing wavelength division multiplexing (WDM) networks. In this paper, by cascading conventional 2×2 TWRs, a new 1×K TWR is proposed for large-scale dynamic wavelength-routing WDM networks. When the cascading numbers are smaller, the 1×K TWR can be directly applied to networking WDM networks. When the cascading numbers are larger, the 1×K TWR can be carried out by the integrating method and be extensively used to networking various multi-wavelength optical networks by the way of “EDFA+TWR”. Though the cascading method proposed is based on the acousto-optic TWRs, it can be also applied to cascading other kinds of TWRs.     

Tbit/s超大容量光纤通信系统的研究进展

Tbit/s超大容量光纤传输系统促进了光纤通信技术的发展。综述了采用波分复用技术(WDM)、光时分复用技术(OTDM)和WDM/OTDM混合方式的Tbit/s超大容量光传输系统的研究现状、技术实现方式及研究的最新进展。对各种传输系统的优缺点进行了评价,对Tbit/s光纤通信系统的前景作了展望。     

Absolute polar duty cycle division multiplexing over wavelength division multiplexing system

The performance of absolute polar duty cycle division multiplexing (AP-DCDM) over wavelength division multiplexing (WDM) system is presented based on the simulation results. The AP-DCDM signal has narrower bandwidth than conventional time division multiplexing (TDM) signal, which makes its implementation in WDM system advantageous. In this paper, characteristics of AP-DCDM and TDM signals in WDM system are compared at the speed of 40 Gbit/s per channel, for the minimum allowed channel spacing and the chromatic dispersion tolerance. The results clearly show that AP-DCDM performs significantly better than TDM. By using AP-DCDM, 1.28 Tbit/s (32 × 40 Gbit/s) was successfully transmitted over 320 km standard single mode fiber. Spectral efficiency of 0.64 b/s/Hz was achieved by using 10 Gbit/s transmitters and receivers without polarization multiplexing.     

Investigations on order and width of RZ super Gaussian pulse in different WDM systems at 40 Gb/s using dispersion compensating fibers

In optical wavelength division multiplexed (WDM) systems the dispersion management is a key issue. In optical systems a lot of research is going on to reduce dispersion by selecting proper dispersion compensating techniques and proper modulation format for input data. One way to reduce dispersion is by using dispersion compensating fibers in the WDM systems. This paper analyzes the use of RZ super Gaussian pulse inputs for different WDM systems i.e. for conventional, dense and ultra dense WDM systems employing dispersion compensating fibers. The pulse width and the order of the RZ super Gaussian pulse was varied to evaluate the performance at 40 Gb/s. The experiment showed that to get minimum BER, pulse width of 7.5 ps and 10 ps along with third-order RZ super Gaussian pulse were found suitable and recommended to be used.     

Algorithm for Scheduling Variable-Length Messages in WDM Networks

In this paper, we develop and analyze a simple algorithm for scheduling variable length messages in WDM networks with a passive star coupler. We base our schemes on a star topology with centralized control and use a scheduling algorithm similar to the process management in UNIX system. Every node and message have a scheduling priority associated with them. By comparing our algorithm with random select algorithm, we find that significant improvement in performance can be achieved with very little extra cost.