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61.
Abstract In this article, two static routing algorithms have been proposed and compared to some of the existing algorithms on the basis of blocking probability. The two proposed static routing and wavelength assignment algorithms reduce the blocking probability to maximize the utilization of the network. All of these algorithms are analyzed and compared with four wavelength assignment schemes, which are first-fit, random, most used, and least used. It is shown that our proposed static algorithms give the best performance for first-fit wavelength assignment and most used wavelength assignment strategies with reduced complexity. For least used wavelength assignment and random wavelength assignment, 1 fixed and 2 alternate routing algorithm gives the lowest blocking probability. 相似文献
62.
提出并验证了一种单-双波长可调谐掺铒光纤激光器。利用级联光纤布拉格光栅(Cascaded Fiber Bragg gratings,Cascaded FBGs)结合Sagnac环结构所产生的复合滤波效应,实现较高精细度滤波,并通过调节环内偏振控制器(Polarization Controller,PC),引入双折射效应,得到波长可调谐的光纤激光器。基于耦合模理论并使用传输矩阵法对该结构的传输特性进行了分析,在此基础上搭建实验系统,验证了理论分析的正确性。实验结果表明:通过调节PC,激光器输出激光的波长范围约为1 555.644~1 556.112 nm,双波长间隔的可调范围约为0.108~0.452 nm,单-双波长的边模抑制比(SMSR)均高于40 dB;在稳定性测试中,输出单-双波长激光的波长最大漂移量小于0.008 nm。该方法具有结构简单、调谐方便、易于实现且精细度较高的优点,可应用于密集波分复用及全光通信系统等领域。 相似文献
63.
介绍了漳州广电网络1 550 nm传输设计方案,包括组网方式和直调1 550 nm光发射机的选型等,阐述了双重保护的概念。就怎样选择EDFA的输出光功率发表了自己的一些看法。 相似文献
64.
《Optical Fiber Technology》2014,20(5):487-490
A dual-wavelength erbium-doped ring fiber laser is proposed and experimentally demonstrated though a detailed theoretical analysis and experimental verification. The proposed dual-wavelength erbium-doped fiber (EDF) laser, which is based on a ring fiber laser structure, is fabricated using two fiber Bragg gratings. By adjusting the gains and losses of the fiber laser structure, the laser can be switched between single- and double-wavelength modes. A saturable absorber (SA) is used to improve the output laser stability, which is further enhanced by splicing a thin core passive fiber (TCPF) into the laser cavity to produce a Mach–Zehnder filter effect. Optimizing the lengths of the SA and TCPF results in the adoption of a 1-m EDF and a 4-m passive fiber. On the basis of these enhancements and optimizations, a fiber laser with stable output is constructed that incurs single- or dual-wavelength laser shifts of less than 3 pm at room temperature over a period of 250 s. 相似文献
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Grooming uniform all‐to‐all traffic in optical (SONET) rings with grooming ratio C requires the determination of a decomposition of the complete graph into subgraphs each having at most C edges. The drop cost of such a grooming is the total number of vertices of nonzero degree in these subgraphs, and the grooming is optimal when the drop cost is minimum. The determination of optimal C‐groomings has been considered for , and completely solved for . For , it has been shown that the lower bound for the drop cost of an optimal C‐grooming can be attained for almost all orders with 5 exceptions and 308 possible exceptions. For , there are infinitely many unsettled orders; especially the case is far from complete. In this paper, we show that the lower bound for the drop cost of a 6‐grooming can be attained for almost all orders by reducing the 308 possible exceptions to 3, and that the lower bound for the drop cost of a 7‐grooming can be attained for almost all orders with seven exceptions and 16 possible exceptions. Moreover, for the unsettled orders, we give upper bounds for the minimum drop costs. 相似文献
70.
An all-to-all routing in a graph G is a set of oriented paths of G, with exactly one path for each ordered pair of vertices. The load of an edge under an all-to-all routing R is the number of times it is used (in either direction) by paths of R, and the maximum load of an edge is denoted by . The edge-forwarding index is the minimum of over all possible all-to-all routings R, and the arc-forwarding index is defined similarly by taking direction into consideration, where an arc is an ordered pair of adjacent vertices. Denote by the minimum number of colours required to colour the paths of R such that any two paths having an edge in common receive distinct colours. The optical index is defined to be the minimum of over all possible R, and the directed optical index is defined similarly by requiring that any two paths having an arc in common receive distinct colours. In this paper we obtain lower and upper bounds on these four invariants for 4-regular circulant graphs with connection set , . We give approximation algorithms with performance ratio a small constant for the corresponding forwarding index and routing and wavelength assignment problems for some families of 4-regular circulant graphs. 相似文献