Multicast wavelength assignment with sparse wavelength converters to maximize the network capacity using ILP formulation in WDM mesh networks

In general, multicast routing and wavelength assignment (MC-RWA) can be subdivided in routing and wavelength assignment issues in wavelength-division multiplexing (WDM) mesh networks. Previous studies on WDM multicast have mainly focused on WDM multicast routing. The multicast wavelength assignment problem is studied in this paper. A unicast routing path can be established by a lightpath in an all-optical network. However, in the multicasting case, a multicast routing tree can be established by a single light-tree or several lightpaths, or a combination of several light-trees and lightpaths. We propose a wavelength assignment algorithm for finding an optimal combination of lightpaths and light-trees to construct a newly required multicast session. First of all, two cost functions are given to evaluate the establishing cost for each feasible wavelength, and then find a set of wavelengths that covers all destinations with the minimal cost using Integer Linear Programming (ILP) formulation. We focus on maximizing the total number of users served in a multicast session and the network capacity. The simulation results show that the proposed algorithm can improve system resource utilization and reduce the blocking probability compared with the First-Fit algorithm.This research was partially supported by the Grant of National Science Council, R.O.C. (NSC 94-2745-E-155-007-URD).     

80nm FBG sensing interrogation system based on tilted FBG

An 800 nm band fiber Bragg grating sensing interrogation system using tilted FBG as the core wavelength division component is presented. A charge coupled device （CCD） linear array is put on the focal plane of the lens to detect the light. TFBG is used to tap light out of the fiber core to fiber cladding. The sensing wavelength is 795 to 830 nm, with accuracy of 20 pm and scan speed 100Hz. Using FBG sensor, we achieve the temperature sensitivity of 1.8 ℃ and strain sensitivity of 18 με.     

Real-time target recognition system simulation based on laser near-field detection

This paper constructs a simulation system of near-field laser imaging for 3D grid model of target, provides some methods for the key problems, such as the modeling of target and laser transceiver, the calculation of laser echo power, the imaging algorithms and so on. A target image library is established by a new imaging method in any rendezvous conditions. The four real-time recognition algorithms which are efficient and suitable for hardware implementation are presented at the conditions of the image incompleteness, intensive noise and arbitrary attitude of target. The experimental results show that all the four algorithms can independently recognize the target effectively and a better recognition effect is obtained by the integration of four algorithms.     

Applying Hopfield neural network to QoS routing in communication network

The main goal of routing solutions is to satisfy the requirements of the Quality of Service （QoS） for every admitted connection as well as to achieve a global efficiency in resource utilization. In this paper proposes a solution based on Hopfield neural network （HNN） to deal with one of representative routing problems in uni-cast routing, i. e. the multi-constrained（MC） routing problem. Computer simulation shows that we can obtain the optimal path very rapidly with our new Lyapunov energy functions.     

Novel algorithm of finding good candidate pre-configuration cycles in survivable WDM mesh network

Pre-configuration Cycle (p-cycle) is a promising ap-proach for protecting working capacities in WDMnet-works because of its ability to achieve ring-like recoveryspeed while maintaining the capacity efficiency of amesh-restorable network[1].The first and t…     

Virtual-node-based multicast routing and wavelength assignment in sparse-splitting optical networks

This paper investigates several problems associated with optical multicast routing and wavelength assignment in sparse-splitting optical networks for interactive real-time media distribution. Unfortunately, the constrained multicast routing with optimized wavelength assignment leads to NP-complete condition. Thus, in this paper, a virtual-node-based multicast routing algorithm is first proposed to satisfy the requirements of interactive real-time multicasting as well as the constraints from underlying optical networks. For the constructed multicast tree, we then associate an effective wavelength assignment algorithm. The experimental results show that the proposed algorithm combination performs well in terms of (1) the wavelength channel cost, (2) the maximum variation of inter-destination node delays, (3) the signal quality, and (4) the number of wavelength conversions.     

Temperature characteristics of InGaAs/GaAs vertical cavity surface emitting laser

The temperature characteristics for the different lasing modes at 300 K of intracavity contacted InGaAs/GaAs Vertical Cavity Surface Emitting Lasers（VCSELs） have been investigated experimentally by using the SV-32 cryostat and LD200205 test system. In combination with the simulation results of the reflective spectrum and the gain peak at different temperatures, the measurement results have been analyzed. In addition, the dependence of device size on temperature characteristics is discussed. The experimental data can be used to optimally design of VCSEL at high or cryogenic temperature.     

Efficient routing and wavelength assignment for multicast in WDMnetworks

The next generation multimedia applications such as video conferencing and HDTV have raised tremendous challenges on the network design, both in bandwidth and service. As wavelength-division-multiplexing (WDM) networks have emerged as a promising candidate for future networks with large bandwidth, supporting efficient multicast in WDM networks becomes eminent. Different from the IP layer, the cost of multicast at the WDM layer involves not only bandwidth (wavelength) cost, but also wavelength conversion cost and light splitting cost. It is well known that the optimal multicast problem in WDM networks is NP-hard. In this paper, we develop an efficient approximation algorithm consisting of two separate but integrated steps: multicast routing and wavelength assignment. We prove that the problem of optimal wavelength assignment on a multicast tree is not NP-hard; in fact, an optimal wavelength assignment algorithm with complexity of O(NW) is presented. Simulation results have revealed that the optimal wavelength assignment beats greedy algorithms by a large margin in networks using many wavelengths on each link such as dense wavelength-division-multiplexing (DWDM) networks. Our proposed heuristic multicast routing algorithm takes into account both the cost of using wavelength on links and the cost of wavelength conversion. The resulting multicast tree is derived from the optimal lightpaths used for unicast     

Improvement of normalized throughput in WDM ＋ OCDMA system using optical hard-limiters

Recently,because of advantages of high-speed opticalprocessing and si mple network control ,the optical codedivision multiple access (OCDMA) has become a hotscheme in LAN and access network[1-5]. According tothe spreading mode, OCDMAcan be mainly dividedi…     

Design of photonic crystal fibers with anomalous dispersion

Photonic crystal fibers (PCFs) have attracted greatattentionin recent years due to their interesting proper-ties ,such as endless single-mode operation,unique dis-persion and nonlinear characteristics[1 ,2].It has been re-ported that PCFs offer a wide range of potential applica-tions ,such as 2Rregenerators ,optical parametric ampli-fiers ,dispersioncompensationandsuper-continuumgen-eration[3].Also called holey fibers or microstructure fi-bers ,PCFs are optical fibers possessing periodic a…     

Magnetic field sensor based on peanut-shape structure and multimode fiber

An all fiber magnetic field sensor with peanut-shape structure based on multimode fiber (MMF) is proposed and experimentally demonstrated. The sensing structure and magnetic fluid (MF) are both encapsulated in capillary, and the effective refractive index of MF is affected by surrounding magnetic field strength. The measurement of magnetic field is realized by observing the wavelength drift of interference peak. The transmission spectrum generated by Mach-Zehnder interferometer (MZI) includes core-core mode interference and core-cladding mode interference. Experimental results demonstrate that the core-cladding mode interference is sensitive to magnetic field, and the magnetic field sensitivity is 0.047 8 nm/mT. In addition, two kinds of interference dips are sensitive to temperature, and the sensitivities are 0.060 0 nm/°C and 0.052 6 nm/°C, respectively. So the simultaneous measurement of magnetic field strength and temperature can be achieved based on sensitivity matrix. This work has been supported by the National High Technology Research and Development Program of China (No.2013AA014200), the National Natural Science Foundation of China (No.11444001), and the Municipal Natural Science Foundation of Tianjin (No.14JCYBJC16500). E-mail:13821538563@163.com      

Design and fabrication of sub-μs silicon-on-insulator thermo-optic 4×4 switch matrix

A rearrangeable nonblocking silicon-on-insulator-based thermo-optic 4x4 switch matrix with spot size converters （SSCs） and a new driving circuit are designed and fabricated. The introduction of a spot size converter （SSC） has decreased the insertion loss to less than 10dB and the new driving circuit has improved the response speed to less than l~s.     

A Study of Broadband Intelligent Network Implementing Video Conference and Multicast Routing Algorithm

A Study of Broadband Intelligent Network Implementing Video Conference and Multicast Routing Algorithm     

Dynamic routing and wavelength assignment in multi-granularity WDM networks

For the purpose of reducing the complexity and cost of optical large-scale cross-connect, wavelengths are grouped into wavebands or fiber to be switched as a single entity, which is called multi- granularity switching. However, it introduces more complexity into the routing and wavelength assignment problem. In this paper, we propose a novel graph model for describing the states of the multi-granularity switching WDM networks. Based on the model, the dynamic routing and wavelength assignment problems for multi-granularity traffic can be solved jointly, and different on-line wavelength grooming policies can be achieved simultaneously. By simulation, we compared the performance of our algorithms under different policy and different percent of fibers for fiber switching. The result proved that our algorithms yield better performance than those deal with the routing and wavelength assignment separately. This work was supported in part by NSFC Project No. 90104003, 60272023, 60372025 and National 863 project No. 2005AA122310.     

WDM疏导网络中一种新的多播业务路由算法

研究了波分复用(WDM)网状网中动态多播业务量疏导,提出一种新的辅助疏导模型,其可以描述当前网络资源状况和节点分光特点,并动态更新.进而提出一种有效的多播业务量疏导启发式算法(MGA),将业务的多播选路和波长分配同时完成.仿真表明,该算法在波长连续性限制、网络波长和节点收发器数目有限的情况下,具有较低网络阻塞率.     

Improved nonlinear multiuser precoding using lattice reduction

Recent theoretical results show that multiuser techniques such as Spatial Division Multiple Access can significantly improve system capacity. In order to achieve this end, lots of precoding methods have been proposed, among which Vector Perturbation precoding has the best Symbol Error Rate performance but with the hugest complexity in searching for the optimal perturbation vector. In this paper, we propose a low complexity, near optimal multiuser precoding method by utilizing lattice reduction of the channel matrix. The perturbation vector is composed of an integer part and a non-integer part, which are designed to simultaneously improve power efficiency and minimize the mean squared error MSE. The integer perturbation vector is calculated implicitly with modulo operation, and the non-integer perturbation can be solved in closed form under MSE minimization criterion. Simulation results demonstrate the effectiveness of the proposed methods. This work was supported by National Basic Research Program of China (2007CB310603), National Natural Science Foundation of China (60496310, 60672093), High Technology Project of China (2007AA01Z262) and Huawei Foudation.     

基于超图模型的多域ASON损伤感知组播路由算法

如何在缺乏全局信息的条件下构建安全可靠的组 播树,是智能光网络分域管理后引入的一个新问 题。针对此问题,通过建立新型的多域智能光网络超图模型,在考虑物理或攻击损伤的约束 条件下,利用 基于超路径的域间超树构建方法,结合K最短路径策略,提出了 一种基于超图模型的多域ASON损伤感知 组播路由算法,并进行了实例分析。本文算法在完成多域组播路由建立与波长分配的同时, 具有较低的时间复杂度。通过测量K值、组播规 模、波长数量及分配策略、域数量对网络平均连接阻塞率的影响,实验结果表明,本文算法 是有效的且取得了较好的阻塞性能,同时建议多域ASON组播规模大小应与域的数量保持一 定的比例均衡。     

Analytic expression of the chirped sampled function used to produce the equal chirp in the specific reflection channel in uniform period fiber Bragg gratings

The general analytic expression of the chirped sampled function is derived based on coupled mode theory. This function can be used to describe how to use uniform period fiber Bragg grating to produce the equal chirp at will in the specific reflection channel. As an example,the exact sampled function expression that produces a linear chirped at the ＋ 4 channel is given. The simulation results by using the transfer-matrix show that the theory is correct.     

Second harmonic generation of a new nonlinear optical material：urea L-malic acid

SinceFrankenfirstobservedthesecondharmonic generationphenomenoninthequartzcrystalin1961,nonlinearoptics(NLO)materialscapableoffrequency conversioneffect,electro opticeffect,andphotorefractiveeffectivehavebeenactivelysoughtoverthelastfour decadesduetotheco…