高功率光纤熔融器件设计综述

近年来,高功率光纤激光发展迅猛,基于光纤熔融器件的全光纤激光系统可以更好地发挥出光纤激光所固有的体积小、质量轻、稳定性和可靠性高等优势。高功率条件下,器件局部发热可能给器件带来灾难性的故障。决定器件高功率承受能力的不是传输功率,而是器件处理光功率损耗的能力。本文详细分析了单模器件和多模器件中的损耗产生机制,指出了低损耗设计的实现方法。减小器件封装的热阻也可以提高器件的功率耐受能力,文中对封装的设计给出了实用的建议。     

DAR成色剂结构与性能的关系

通过分析DAR成色剂的结构和作用机理,讨论了其结构与照相性能之间的关系.DAR成色剂的结构可表示为:Cp—L—A,其中Cp代表成色剂母体,A代表促进显影的功能基团即增强基团,L代表连接基团同时也有吸附功能即吸附基团.本文指出:当吸附基团和增强基团相同时,母体对照相性能影响不大;当母体及增强基团相同时,吸附基团的吸附性越强,照相性能越好;当母体及吸附基团相同时,增强基团的感染显影作用越强,照相性能越好.     

数码摄影中的化学

数码摄影已成为人们日常生活的一部分。在阐明数码摄影原理的基础上,着重介绍了数码相片冲印过程中一些重要的化学反应,以凸显化学在数码摄影中的作用。     

明胶层中的扩散和反应的动力学研究——(Ⅴ)油溶性成色剂的偶合反应的动力学

研究了明胶层中油溶性成色剂油珠的偶合反应动力学。通过实验和数值模拟的比较证明:在明胶层中油溶性成色剂(C-1)油珠与彩色显影剂CD-4的氧化产物的偶合反应主要是发生在油珠-明胶水溶液的界面上。偶合反应速度与油珠大小、比速率常数、成色剂在油相中的浓度以及QDI的扩散系数有关。并且得到C-1成色剂油珠的比速率常数、CD-4氧化产物的扩散系数以及QDI和生成的染料在明胶层中的时空分布。同时观察到温度对偶合反应动力学的影响。     

Analysis of Coupling and Radiation Properties for an Improved Dielectric Waveguide Directional Coupler Utilizing a Tapering Left-Handed Slab Core

The coupling and radiation characteristics of an improved dielectric waveguide directional coupler with a tapering left-handed slab core located in the coupling region are analyzed by the staircase approximation method, which combines the building block approach and multi-mode network theory with a rigorous mode-matching procedure. Particular attentions are directed toward the radiation characteristics under different structural parameters of the coupler. Numerical results indicate that the proposed coupler is very promising by shortening the coupling length significantly while keeping the radiation loss at a low level.     

A numerical model of multimode fiber PON frequency response

Frequency response of passive optical network (PON) based on multimode fibers is investigated. The network comprises fibers, connectors and splitters/couplers. It is shown that due to mode filtering at splitters, the frequency response is different for different network nodes in otherwise symmetrical network.     

基于MSC Pool的软交换组网策略

随着软交换大规模投入使用,如何在兼顾网络资源、注重网络安全的基础上,有效简化网络扩容、合理配置MSC/MSC Server的容量及分担话务已经成为中国移动日益关注和重视的焦点。文章通过对MSC Pool技术原理、基本业务流程以及特点优势的介绍,由此引入基于MSC Pool的软交换组网策略,并就发展趋势、规划原则以及最终目标做了分别阐述和分析。     

一种双频微波功率合成器的设计与实现

一种新型的双频微波功率合成器，通过阶跃阻抗低通滤波器和平行耦合线带通滤波器构成的微带电路实现。该微波功率合成器实现了915MHz和2．5GHz两个非相干频率微波信号的功率合成。同时通过附加工作在915MHz和2．5GHz的20dB微带定向耦合器，就可以构建实验系统进行微波功率合成的测量。实验测量结果与数值模拟结果吻合，双频微波功率合成器和定向耦合器的性能达到了要求，可用于注入式微波器件效应的研究。     

光纤传输脉冲固体激光切割机系统

介绍了光纤传输脉冲固体激光切割机系统的设计原理及工作特点,主要是优化设计光纤传输系统,使光纤输出后的激光束聚焦光斑直径尽量小;满足激光切割所需功率密度要求。系统使用双灯单棒的聚光腔,光纤输出后的功率达到400W,最小光斑直径小于0.25mm,可满足1~4mm内的碳钢、不锈钢等金属材料的切割要求。该系统可配合数控工作台、...     

A Multilayer Optical Packet Switching Network Based on the Kautz Graph and Optical Passive Star Couplers

The multihop optical network is the most appropriate solution to satisfy the increasing applications of Internet services. This paper extends the regular Kautz graph to one with multiple layers in order to produce more architectural variations. The connectivity between adjacent layers utilizes the systematic connection patterns of a regular Kautz graph. A routing algorithm based on its property is presented. Optical passive star (OPS) couplers are adopted to implement our new topologies. Three scheduling criteria that can solve the contention problem in the intermediate nodes are evaluated and compared in terms of their capability to improve the accessibility.