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.     

Metropolitan DWDM: a dynamically configurable ring for the KomNetfield trial in Berlin

We present the system concept of a dynamically configurable all-optical add/drop multiplexer for metropolitan wavelength division multiplex rings using dense channel spacing (DWDM). We first outline the essential network requirements. Subsequently, an optical system concept is presented that meets these requirements. In the network elements, innovative all-optical switching technology is employed. Tunable fiber Bragg gratings that perform routing functions by wavelength filtering are discussed in more detail. The system is laboratory-tested. It has been installed in Berlin for a multi-vendor field trial within the German research program “KomNet.” Three optical add/drop multiplexers form a dynamically configurable Metro DWDM ring. Metro DWDM accommodates high bandwidths: a metropolitan ring that provides 0.8 terabit/s ring capacity has been demonstrated. Furthermore, Metro DWDM can provide optically transparent channels enabling the transport of various data formats simultaneously, e.g., SONET/SDH and Gigabit Ethernet. Conversion to a standard format becomes obsolete. The all-optical add/drop multiplexer (OADM) presented provides both manual and dynamic configuration. The system concept of the OADM is developed starting with basic metropolitan DWDM network requirements. The features of the DWDM ring are described, followed by a presentation of the system concept of the flexible OADM. Our focus is on dynamic configuration techniques. Since tunable fiber Bragg gratings are promising components for dynamic optical channel switching, this technology is treated in more detail     

More than 1000 channel optical frequency chain generation fromsingle supercontinuum source with 12.5 GHz channel spacing

More than 1000 optical frequency channels are generated with 12.5 GHz spacing from a single supercontinuum source. 600-700 channels for the wavelength range 1512-1580 nm are confirmed to offer SNRs and Q factors sufficient for multi-span 2.5 Gbit/s DWDM transmission     

Crosstalk Analysis of a Fiber Laser Sensor Array System Based on Digital Phase-Generated Carrier Scheme

A detailed study on analyzing the crosstalk in a wavelength division multiplexed fiber laser sensor array system based on a digital phase generated carrier interferometric interrogation scheme is reported. The crosstalk effects induced by the limited optical channel isolation of a dense wavelength division demultiplexer (DWDM) are presented, and the necessary channel isolation to keep the crosstalk negligible to the output signal was calculated via Bessel function expansion and demonstrated by a two serial fiber laser sensors system. Finally, a three-element fiber laser sensor array system with a 50-dB channel-isolation DWDM was built up. Experimental results demonstrated that there was no measurable crosstalk between the output channels.     

Dispersion effects of FBG filter and optical SSB filtering in DWDM millimeter-wave fiber-radio systems

We study the optical filtering technique for dense wavelength division multiplexing (DWDM) channel allocation of millimeter-wave fiber-radio signals in the optical double-sideband (DSB) format. First, we investigate both theoretically and experimentally the dispersion effect of fiber Bragg grating (FBG) used as the filter on DWDM millimeter-wave optical signal transmissions. This result suggests that the dispersion effect has to be considered in the DWDM channel allocation for millimeter-wave fiber-radio access systems. Next, we propose a DWDM allocation for millimeter-wave fiber-radio systems, which adopts the optical single-sideband (SSB) filtering technique at the receiver side by using a square response of FBG filter. It can realize the minimum WDM channel interval for optical DSB signals, while it enables the optical frequency interleave between the neighboring channels without any serious signal degradation due to the interchannel interference. Then, we experimentally demonstrate the error-free DWDM transmission of two 60-GHz-band, 155.52-Mb/s differential phase-shift keying (DPSK) fiber-radio signals over 25-km-long single-mode fiber (SMF) with the minimum channel interval of 83.6 GHz (=0.68 nm) by using the test-square response FBGs. Finally, we show that based upon the experimental results, in the micro- or pico-cellular DWDM broad-band millimeter-wave fiber-radio access network 1000 antenna base stations (BSs) under the coverage of the single central office (CO) would be feasible by sectorizing the zone.     

DWDM光纤通信系统中受激喇曼散射的统计特性

随着通信容量的增大,密集波分复用(DWDM)光纤通信系统中的受激喇曼散射(SRS)非线性效应成为影响系统质量的重要因素.采用时域分步法模型,对色散下的SRS统计特性进行了深入研究,得到了在整码元色散走离时,DWDM系统各信道传输功率的统计特性,推导了各信道传输功率的数学期望、标准差,证实了各信道传输功率符合高斯分布,计算了概率密度函数,并且与仿真数据取得了较好的一致.

Abstract：

With the enlargement of communication capacity, the performance of dense wavelength division multiplexed (DWDM) fiber communication systems might be degraded by nonlinear effect of stimulated Raman scattering (SRS) in the optical fiber. To resolve these problems, the time-domain split-step method is applied to investigate the statistical characteristics of SRS. The mean and the standard deviation of transmission powers of all channels are derived analytically in a closed-form formula for DWDM systems with SRS and integer bits dispersion walk-off. The probability density function (PDF) of output powers of all channels is confirmed to be Gaussian distribution. The numerical results show a good correspondence with analytical formulae.     

Configuration of more than N DWDM channels with only one N × N cyclic-AWG-based wavelength routing device

A wavelength routing device based on only one N × N cyclic arrayed waveguide grating (AWG) having easy extended channels configuration is presented in this paper. It is easy to extend the dense wavelength division multiplexing (DWDM) channel configuration through this wavelength routing device. According to the cyclic wavelength of AWG, the wavelength routing devices are easy to configure more than N extended DWDM channels through cascading more proper tunable fiber Bragg gratings (FBGs). With only one 8 × 8 AWG, two different wavelength routing structures were built to evaluate static crosstalk and the bit-error-rate (BER). Three of the 16 inputted DWDM channels were demonstrated to verify that the proposed wavelength routing device, with only one 8 × 8 AWG, could configure extended DWDM channels without interfering with other channels. The results show that the wavelength routing device can produces a better performance and offers a cheaper way to extend the DWDM channel configuration for a dynamic network.     

Bidirectional Hybrid DWDM‐PON for HDTV/Gigabit Ethernet/CATV Applications

A new scheme for bi‐directional HDTV/Gigabit Ethernet/CATV transmission over a hybrid dense‐wavelength‐division‐multiplexing passive optical network (DWDM‐PON) is proposed and demonstrated. It is based on injection‐locked vertical‐cavity surface‐emitting lasers and distributed‐feedback laser diodes as transmitters. Services with 129 HDTV channels, a 1.25 Gbps Gigabit Ethernet connection, and 77 CATV channels are successfully demonstrated over 40 km single‐mode fiber links. Good performance of bit error rate, carrier‐to‐noise ratio, composite second order, and composite triple beat is achieved in our proposed bidirectional DWDM‐PON.     

DWDM网中全光波长转换器的研究

全光波长转换器（AOWC）是未来DWDM网络中关键性器件之一，文章介绍了DWDM网中几种AOWC的实现方法、原理和进展情况，还简单介绍了波长转换器在DWDM网中的最优化放置问题。     

Simultaneous electrooptical upconversion, remote oscillatorgeneration, and air transmission of multiple optical WDM channels for a60-GHz high-capacity indoor system

The system concept and data transmission experiments for a mobile broad-band communication system at 60 GHz are presented in this paper. Dense wavelength division multiplexing (DWDM) is advantageously applied for simultaneous electrooptical upconversion of all optical channels carrying individual intermediate-frequency signals by means of a single external modulator. Thus, simple, but flexible, millimetric signal generation is obtained. Using this concept, data transmission experiments at 60 GHz have been carried out. Furthermore, the transponder noise performance is analyzed. Results of coded and uncoded 512-carrier orthogonal frequency division multiplex transmission with 50-Mb/s (subcarrier modulation quaternary phase-shift keying), 100 Mb/s (subcarrier modulation 16-quadrature amplitude modulation) as well as single-carrier modulation at 156 Mb/s utilizing three operational DWDM channels are presented. Uplink and downlink transmission has been realized. The significant performance improvement due to the application of coding is demonstrated in some experiments and line-of-sight transmission is compared to nonline-of-sight transmission. Low bit error rates, employing realistic air link conditions, have been obtained in all experiments     

基于Sagnac干涉仪的级联型梳状滤波器

密集波分复用(DWDM)系统光信道数量的增加,使得与DWDM技术有关的各种光学滤波器技术成为当前光纤通信领域的研究热点.高双折射(HiBi)光纤环具有易于制作、性能稳定以及良好的滤波特性等特点,近年来受到广泛关注;通过增加Sagnac环内HiBi光纤和偏振控制器的个数,或者采用多个HiBi光纤Sagnac环的级联形式,...     

Fiber-grating add–drop reconfigurable multiplexer with multichannel using in bi-directional optical network

A bi-directional reconfigurable scheme of multichannel-selective optical add–drop multiplexer (OADM) is proposed in this paper. With only small wavelength channel tuned range, the proposal applies fiber Bragg gratings (FBGs) and multiport optical circulators (MOCs) to build a bi-direction reconfigurable OADM which can deal with full channels without the receiving signal having wavelength-interleaved. Moreover, it is easier and more flexible to extend wavelength channels by cascading additional FBGs. The magnitudes of homodyne and heterodyne crosstalks are analyzed for evaluating the performance of the proposed BOADM. Also, the power equalization of each signal in the add–drop and output ports is managed properly by implementing filters. As a result, the BOADM will be found in wide applications in dense wavelength-division multiplexing (DWDM) optical networks and in multiwavelength crossconnects (WXCs).     

MEMS tunable SOI waveguide Bragg grating filter with 1.3 THz tuning range for C-band 100 GHz DWDM optical network

A MEMS tunable integrated waveguide Bragg grating-based filter for C-band optical dense wavelength-division multiplexing (DWDM) network is presented and analyzed in this work. Waveguide Bragg grating being a notch filter in the transmission spectrum is used to realize a tunable filter by varying the applied voltages to the fixed–fixed beam loaded with this grating. The strain across the grating is enhanced by choosing MEMS beam configuration such that the metal electrode is the bottom-most layer of the composite fixed–fixed beam. Device dimensions are chosen to achieve a narrow full width half maximum of 0.77 nm, allowing filtering of adjacent channels of 100 GHz DWDM network. A large Bragg wavelength shift of 10.4 nm (1552.52–1562.92 nm) was achieved at 45.8 V actuation providing tuning for 14 DWDM channels with inter-channel cross talk below ? 21 dB, with tuning range of 1.3 THz.

     

基于FPGA的DWDM光源控制系统

设计了一种新型的DWDM光源控制系统,该系统采用MCU FPGA技术,可以同时对多个DWDM光源通道进行温度、波长和功率的检测控制,并且通过GPIB总线实现了PC机的远程控制.数字控制系统中FPGA技术的采用降低了系统的复杂性,提高了系统的可靠性和灵活性.在温度控制模块中,采用分阶段模糊控制的方法提高了系统的响应速度和控制精度.在LD控制模块中采用新型的波长锁定技术实现波长的高精度控制,同时采用软启动、限幅电路和短路开关等措施进行LD的浪涌保护.实验研究表明,该系统的温度和波长控制效果较好,而且能抑制因老化引起的波长漂移.     

光通信用DWDM器件的制作工艺及其参数测试

密集波分复用(DWDM)是光纤通信增容的首选方案,而波分复用/解复用器件(DWDM器件)是DWDM系统中的关键器件。本文讨论了DWDM器件的几种典型制作方法,其中薄膜滤光片(TFF)型器件是最富竞争力的,并对TFF 型DWDM器件的制作工艺、主要特性参数及其测试方法开展了实验研究,对我们自行研制的四通道TFF型DWDM器件的测试结果表明:该器件具有精确的中心波长、宽且平坦的带通、小而均匀的插入损耗以及较大的信道隔离度等特性,具有很好的应用前景。     

新型密集波分解复用器的实验研究

为了易于实现解复用波长数目和间隔上的升级,设计了一种新型16波长/100GHz间隔密集波分解复用器.该器件由100GHz光梳状滤波器和200GHz介质膜滤波器构成:利用光梳状滤波器的并行输出来扩展解复用信道之间的间隔,通过介质膜滤波器的串联来实现不同波长的解复用.实验研究表明,该器件具有良好的性能,能够满足系统升级的需要.     

Network Access to 2000 WDM Channels at 2 GHz Granularity with a Single Laser in C-band

As WDM channel spacing continues to decrease in size, and with the application of tunable lasers in DWDM (dense wavelength division multiplexing) systems, we demonstrate the ability of electronically tuned lasers to cope with demanding channel spacing and inevitable low frequency setting error. By finding the stable operating points of a single tunable laser at the desired frequencies, using advanced software for feature extraction a look-up table to drive the laser was generated. Once the drive currents to access 2000 channels in a 2 GHz comb are found, and in order to justify their usability in WDM networks, their frequency setting error and Side Mode Suppression Ratio (SMSR) was found. These results open up new possibilities for DWDM access networks while pointing to new potential for management of versatile wavelength re-allocation as well as providing a limit of achievement for channel density and granularity in the optical fiber network.     

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。     

Monolithically integrated optical channel monitor for DWDM transmission systems

The design, fabrication, and performance of an InP-based monolithically integrated optical power monitor are presented. It contains 44 wavelength channels separated by 100 GHz and demonstrates record small footprint size. The device's major components, which include the echelle diffractive grating demultiplexer, passive waveguide circuitry and single-mode vertically integrated waveguide PIN photodetectors, are characterized and discussed as generic building blocks of InP-based planar lightwave technology for DWDM.     

A wavelength routing device by using cyclic AWGs and tunable FBGs

This paper presents a dense wavelength-division multiplexing (DWDM) routing device based on a pair of 1 × N and N × 1 cyclic array waveguide gratings (AWGs) and tunable fiber Bragg gratings (FBGs) to configure all channels in a dynamic network. With the AWG cyclic spectral routing rule, all the DWDM channels (e.g., more than 8 DWDM channels can be configured based on a pair of cyclic 1 × 8 and 8 × 1 AWGs) can be added and dropped by using the multiple tunable FBGs to reflect the channels that need to be dropped to the drop port as well as to reflect the local DWDM channels that are same as the drop wavelength channels to the output port. Three DWDM channels are demonstrated to verify that all the DWDM channels can be added and dropped in one pair of cyclic AWGs. The results show that the proposed DWDM routing device is feasible to use and offers more flexibility in all-optics dynamic networks.