超密集波分复用无源光网络技术

超密集波分复用光接入网(UDWDM-PON)方案可以在C波段密排1 000个下行波长和1 000个上行波长,支持1 000个用户。每个用户独立使用一对波长,可实现速率千兆并具有速率万兆的潜力。使用分光器兼容现有光分配网,采用数字相干通信技术,功率预算将可超过43 dB。UDWDM-PON在用户带宽保证、容量汇聚能力、网络覆盖范围等方面发展潜力明显。     

Tunable dual-wavelength picosecond optical pulses generated from aself-injection seeded gain-switched laser diode

A novel scheme to generate dual-wavelength picosecond optical pulses has been demonstrated. The pulses are obtained by self-injection seeding of a gain-switched laser diode simultaneously at two different wavelengths. Optical feedback is provided by a partially reflecting fiber mirror. Single-mode pulses at alternate wavelengths around 1.3 μm have been generated. The pulse width varies from about 40 to 50 ps. The output wavelengths can be tuned by changing the electrical modulation frequency. Spacing between the wavelengths can also be controlled by adjusting the length of the dispersive fiber cavity. Our experimental data are in good agreement with the calculated results     

不同波长近红外激光大气消光特性的泛化回归神经网络反演算法

由于大气的不均匀性和不稳定性,采用MODTRAN等大气传输软件计算,很难保证实时精确地获取某波段的近红外激光大气消光系数、大气透过率等消光特性,且传统的手段存在很多不确定性因素.利用近红外波段激光不同波长大气消光特性之间的相关性和泛化回归神经网络,可以实现输入到输出之间非线性的相关性函数关系,通过已知波长的激光雷达实测数据来实时反演其他波长的大气消光特性.实践表明,该方法为实时获取实战条件下某一波段近红外大气消光特性提供一种新方法.     

用于眼底治疗的三色激光系统

为了广泛适用于多种眼科疾病的激光治疗,介绍了一种可以产生红、黄、绿三色激光的眼科治疗系统。在此系统中,使用2台全固态激光器,通过倍频分别获得红、绿光,再通过光纤耦合及光纤混频,实现红、黄、绿三色激光根据使用需要单独工作或者同时工作。其中红外基频光1320 nm与1064 nm分别达到26 W与47 W;660 nm红光与532 nm绿光分别达到1 W与1.9 W,单独光纤输出分别达到0.8 W与1.5 W;并实现Y型光纤混频输出功率达到1.6 W。该系统能使红、黄、绿三色激光发挥在眼科治疗中各自的优势,并互补不足。     

双波长光纤光栅外腔半导体激光器中波长转换

提出了基于双波长光纤光栅外腔半导体激光器增益饱和效应的全光波长转换方案，特点是可将输入信号同时转换到激光器的2个波长上。在静态波长转换实验中，观察到了1554.8nm输入信号对激光器1531.5nm与1549.4nm波长输出功率的增益饱和作用。表明可实现输入信号到激光器的两个波长的同时转换。     

Analysis of optical gain enhanced erbium-doped fiber amplifiersusing optical filters

Erbium-doped fiber amplifiers (EDFAs) with enhanced optical gain obtained by incorporating narrow-bandpass optical filters into the amplifier length are studied. It is shown in theory that it is possible to increase optical gain by more than 10 dB for optical signals around the wavelength of 1.55 μm, compared with conventional EDFAs without filters. It is also shown that the gain improvement at longer wavelengths away from the amplifier gain peak is much higher than that of the EDFA with an optical isolator within the amplifier length. The optimum filter position is found to be around 42% of the total amplifier length from the input end. The effects of filter insertion loss and pump loss are discussed. This amplifier can be used as an optical preamplifier in a receiver for a wide range of wavelengths     

Optimal dimensioning of the WDM unidirectional ECOFRAME optical packet ring

To efficiently support the high rate and the high dynamicity of the traffic in metro networks, an optical packet-switched WDM ring, named ECOFRAME, is proposed. The key features of the proposed ring are optical transparency and statistical multiplexing of optical packets on parallel WDM channels. Such features can be exploited by properly allocating wavelengths and receivers. This paper aims to optimally dimension the unidirectional ECOFRAME rings. The dimensioning at minimum cost (i.e., for wavelengths and receivers) is modeled with an mixed-integer linear programming formulation. An heuristic algorithm is also proposed, and its performance is compared against the optimal solutions and bounds. When considering the receiver and wavelength cost, results indicate that trading the wavelengths for receivers allows cost saving of up to 75% with respect to WDM optical packet rings with a single dedicated wavelength per node (i.e., single receiver at each node).     

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...     

Optical Path Length,Temperature, and Wavelength Effects Simulation on Ozone Gas Absorption Cross Sections towards Green Communications

Ozone is a green house gas. Ozone absorption cross sections have been reported with discrepancies and inconsistencies. In this paper, simultaneous effects of the optical path length and temperature variations on ozone gas absorption cross sections are investigated at different wavelengths. HITRAN 2012, the latest available line list on spectralcalc.com simulator, is used in this study to simulate ozone gas absorption cross sections in relation to the simultaneous effects of the optical path length and temperature at the wavelengths of 603 nm and 575 nm. Results obtained for gas cells with the optical path length from 10 cm to 120 cm show that the decrease in temperatures from 313 K to 103 K results in the increase in ozone gas absorption cross sections. At wavelengths of 603 nm and 575 nm, the percentage increase of ozone gas absorption cross sections is 1.22% and 0.71%, respectively. Results obtained in this study show that in the visible spectrum, at constant pressure, ozone gas absorption cross sections are dependent on the temperature and wavelength but do not depend on the optical path length. Analysis in this work addresses discrepancies in ozone gas absorption cross sections in relation to the temperature in the visible spectrum; thus, the results can be applied to get optimal configuration of high accuracy ozone gas sensors.     

智能型植物工厂光谱监测中的光学膜设计

介绍了一种设施农业中用于光谱监测的光学膜设计,主要利用截止滤波器的组合得到了三种设施农业用光学膜——红光膜、蓝光膜及红蓝滤光膜,红、蓝光中心波长分别在 460nm和660nm,透光带宽约50nm。红、蓝光透光波段根据植物对光谱的需求设定,在实际应用中可根据需要设定其透光的中心波长及带宽。该滤光片可用于制作设施农业及农业研究中的光谱监测单元,该光谱监测单元是将特定的光学膜片置于晶硅光伏芯片上,通过测定光伏芯片的发电量来监测光学膜片预设波段的光强度。     

基于三频光外差法产生毫米波的研究

将三频光外差法运用到光纤无线系统(Radio-over-Fiber)中,研究了一种采用三频光外差法产生毫米波的RoF系统.在中心站产生三路不同波长的窄线宽光波,其中两路光波分别由光调制器调制上数据信号,另外一路作为本振光.经光纤传输后,再通过基站光探测器的探测混频产生两个不同频率的毫米波信号.结果表明,采用三束波长为1549.68nm、1549.52nm和1550nm的光波可产生两路分别携带10Gb/s下行基带数字信号的频率为40GHz和60GHz的毫米波,并实现基带信号在单模光纤中 20□的传输.     

Arrayed waveguide gratings for wavelength routing

Wavelength routing can be performed in the optical domain for both long-haul and passive optical networks. Arrayed waveguide gratings (AWGs) can perform wavelength routing for a large number of optical channels and provide a high level of functionality on an integrated chip. The AWG guides light on a planar lightwave circuit into an array of waveguides that provide dispersion to separate the different wavelengths of light. Routing functions can be performed on individual wavelengths. With this technology, optical cross-connects, optical add/drop multiplexers, and passive optical routers have been demonstrated. Performance issues-such as insertion loss, polarization dependence, passband shape, passband position, crosstalk, and temperature dependence-are being addressed so that AWGs will be practical for deployment into systems     

Multicasting in a class of multicast-capable WDM networks

Multicast is the ability to transmit information from a single source node to multiple destination nodes. Multicast can be supported more efficiently in optical domain by utilizing the inherent light-splitting capacity of optical switches than by copying data in electronic domain. In this paper, we study multicast communication in a class of multicast-capable WDM networks (i.e., the networks that have light splitting switches) with regular topologies under some commonly used routing algorithms. Upper and lower bounds on the minimum number of wavelengths required are determined for a network to be rearrangeable for arbitrary multicast assignments, and compared with those WDM networks without light splitting switches. Our results indicate that in most of the networks we study, the number of wavelengths required can be significantly reduced by utilizing light splitting switches     

Network performance and integrity enhancement with optical pathlayer technologies

Path layer technologies will play a key role in the development of a powerful and failure resilient B-ISDN. So far, they have been based on electrical technologies. This paper highlights WDM/FDM techniques and demonstrates that optical paths can greatly enhance the path layer capability and, therefore, the network performance. It is also shown that effective network failure restoration can be achieved with optical paths. The applicability of the wavelength path (WP) technique to global area networks is revealed by comparing different optical path realization techniques. WPs are applied to the national backbone network example to evaluate the required number of wavelengths, and to identify optical cross-connect node requirements. It then proposes a new optical path concept: the virtual wavelength path (VWP). In the VWP scheme, wavelengths are assigned on a link-by-link basis. In other words, the wavelength assigned to a wavelength path has only local significance. Significant benefits of the VWP such as the simplified path accommodation design within a transmission facility network and the reduced number of wavelengths needed, are elucidated. An optical cross-connect node architecture that enables the VWPs is also proposed. The architecture allows the VWP concept to be realized with commercially available optical technologies. The optical path layer concept proposed exploits and consolidates the layered transport network architecture and optical technologies, and will open up new opportunities for creating a B-ISDN that is bandwidth abundant and has a high degree of integrity     

接近于零色散的色散平坦光子晶体光纤的数值模拟与分析

基于标量近似理论利用有效折射率方法对低空气填充率的光子晶体光纤 (PCF)的色散特性进行了数值模拟。发现通过调节光纤包层的空气穴节距或空气穴大小可以有效地调节光子晶体光纤的色散特性 ,可以实现光子晶体光纤零色散波长向短波方向 (小于石英材料的零色散波长 1 2 7μm)移动 ,甚至在光通信波段出现两个零色散波长 ;可以设计在光通信波段接近于零色散的色散平坦光子晶体光纤 ,其色散系数D的绝对值在 1 2～ 1 7μm波长范围小于 2 0 ps·km-1·nm-1,其色散斜率D′的绝对值小于 0 0 2 ps·km-1·nm-2 。     

Photonic Crystal Fiber Beamformer for Multiple X -Band Phased-Array Antenna Transmissions

A multiple-beam optical beamformer based on highly dispersive photonic crystal fibers (PCFs) is presented. Each radio-frequency (RF) beam can be independently controlled to steer continuously. The dispersion of the fabricated PCFs is as high as -600 ps/nmldrkm at 1550 nm. Simultaneous two-beam transmission is demonstrated using two lasers with different optical wavelengths. The two wavelengths generate two independent sets of time delays, which correspond to two independent RF beams.     

窄线宽光子晶体红外光滤波器研究

利用传输矩阵法研究了光通信中850nm、1330nm和1550nm三个波长的光子晶体滤波器。研究了如何通过选择各层的折射率及宽度使滤波器工作在给定的波长上并具有极窄线宽的方法。经过数值计算分别得出了工作于这三个波长上的光子晶体滤波器的参数。计算结果表明,当缺陷模厚度保持不变时,中心波长会随折射率的增大向长波移动。通过选择适当的参数,可制作出工作于850nm、1330nm和1550nm波长上的线宽为0．0001nm的极窄线宽光子晶体滤波器。     

用波分复用技术设计和实现的双波长光纤环网

本文设计和实现了具有PCI总线峰值带宽传输能力的光互连网络接口卡。采用可编程门阵列实现硬件路由和同步流水线传输以减小数据包在网络中的通信延迟。为扩展网络规模,采用波分复用技术实现了双波长环网。通过无源光学器件实现双波长信号和合波和分束,通过探测器选择接收不同波长的光信号以实现波长路由。该网络结构扩展为多波长环网。     

Mixed-line-rate optical network design with wavebanding

To cope with ever increasing and more heterogeneous traffic demands, today’s optical backbone networks are expected to support mixed line rates (MLR) over different wavelength channels. MLR networks can be designed to provide flexible rate assignments to low-bit-rate services and high-bit-rate services in a cost-effective manner. But with increasing number of wavelengths in the network, aggregating wavelengths into wavebands can further reduce the network cost.In this study, we incorporate the idea of waveband switching in MLR network design. Wavebanding or grouping of optical paths reduces the optical switch size at the optical cross-connects (OXCs). When several lightpaths share several common links, they can be grouped together and routed as a single waveband. For optical bypass at a transit node, only two optical ports are required for each waveband, hence reducing the port cost. It can be a challenge for an MLR network to waveband wavelengths of different line rates that have different transmission reaches. In our design, we present a suitable switching architecture and propose an efficient and cost-effective approach for wavebanding in an MLR network. The design problem is formulated as a mixed integer linear program (MILP) where the objective is to minimize transponder cost and port cost. A heuristic algorithm for wavebanding in MLR networks is provided. To further optimize our solution, we also present a Simulated Annealing algorithm for wavebanding. Our results show a significant improvement in cost savings compared to single-line-rate (SLR) networks with wavebanding and an MLR network employing only wavelength switching.     

Influence of the IP Traffic Asymmetry on the Cost of the Optical Network Layer

The main traffic to be carried by a backbone network in the future (or even now) will be (is) IP traffic, which is unidirectional and asymmetric in nature. Today, most backbone networks are still designed for bidirectional, symmetrical services like SDH/SONET. In the future, the transmission links in the optical layer will probably still be symmetric (same amount of capacity installed in both directions of the optical link), and operators will probably continue to lease bidirectional capacity to their customers. However, the traffic that will be conveyed over those bidirectional transmission links will be mainly unidirectional and asymmetric. This paper studies the influence of the asymmetric nature of IP traffic on the underlying optical layer. In case the optical layer contains bidirectional symmetric capacity (as is almost always the case nowadays), it shows how cost(in)efficient this optical capacity is used for IP traffic patterns with varying asymmetry. The comparison is also made with a unidirectional optical layer, in which the capacity (line-systems) installed in the network is asymmetric (more capacity can be present in one direction of an optical link than in the other direction), or in which the capacity that is leased by operators is asymmetric (e.g., an ISP can choose to lease two wavelengths from city A to city B and five wavelengths in the other direction, from city B to city A).