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With the support of a major research grant of Zhejiang Province (No. 001101027) and the Plan of Promoting Education of Excellence of Zhejiang University in the 21st Century, this dissertation is devoted to address the above problems and fabricate an L-band EDFA with low cost, high performance and technological innovation.First the mechanism of an erbium doped fiber amplifier is introduced. Various theoretical models based on classical rate propagation equations are summarized and compared for their applications. We use a modified numerical model based on the Giles model, which agrees with the experimental results well. This serves as the theoretical base for the whole thesis and will be used to optimize the characteristics of EDFAs. A novel method based on a map of noise figure and gain is proposed to analyze efficiently the dependence of the noise figure and gain for EDFAs on the EDF length and the pump power. The characteristics of various EDFAs are studied and compared.Secondly, some important parameters are introduced to describe the characteristics of EDFAs. The methods and the experimental setups for measuring the gain and noise figure of an EDFA are emphasized. We introduce how to measure the characteristics of each component of an EDFA, especially the gain and absorption coefficient of an erbium doped fiber.Thirdly, four types of simple and novel L-band EDFA structures with low noise, high gain and low gain ripple are proposed to satisfy the requirement of a DWDM system. They can be classified into two categories. In the first category, a single ASE pumping is served asa secondary pump. This category includes the following three types. Type: a new construction using a fiber Bragg grating in an unpumped EDF section at the input side. Type: a new structure of L-Band EDFA with two-stage pumps, which utilizes the forward ASE as a second pump.

本论文本着科技创新、服务于生产实践的精神，以设计价格低廉，性能优越、结构合理简单的L-band EDFA为目标，依托浙江省科技厅重大科学基金资助项目(001101027)和浙江大学振兴教育计划资助的全光网络的搭建—《光通信技术》课程实验建设项目，展开了如下工作：首先，介绍了掺铒光纤放大器的工作原理，归纳总结了基于速率方程基础的EDFA的各种理论模型，分析比较了各个模型的特点和适用场合，最终选择完善的Giles理论模型作为本论文分析设计EDFA的理论基础；针对实际实验条件提出了修正的EDFA模型的数值计算方法；创新地提出了增益—噪声系数全局分析法，直观有效地分析了EDFA的增益和噪声系数与掺铒光纤长度和泵浦功率的依赖关系，并对各种EDFA的性能作了全面的比较；第二，介绍了掺铒光纤放大器特性参数的定义与测量方法，重点介绍了噪声系数和增益系数的测量方法及实验装置；介绍了组成掺铒光纤放大器各组件的特性测量方法，重点介绍了测量掺铒光纤参数的方法和实验装置；第三，针对WDM系统对L-band EDFA谱平坦、低噪声、高增益的要求，我们创新地提出了四种不同的L-band EDFA结构，按设计思路可以分为两大类：一类是基于单抽运二级泵浦法，这一类包括在未泵浦掺铒光纤的输入端插入一根布拉格光纤光栅的两段L-band的EDFA的新结构；基于前向ASE光作为二级泵浦源推动下一级EDF工作的泵浦分配、两段级联L-band的EDFA的新结构；基于单根光纤光栅、泵浦分配、两段级联的EDFA；另一类则是基于同时应用前后向C-band ASE作二级泵浦源的双抽运法，如基于前后向ASE光作为二级泵浦源的三段级联L-band的EDFA的新结构。

Two series of polyurethane acrylate grafted acrylic resins (Acr-g-TPU-PETA and Acr-gPPU-PETA) self-emulsifying systems are obtained by grafting -NCO group modified polyurethane acrylates with acrylic copolymer prepared from n-butyl acrylate, styrene,βhydroxyethyl methacrylate and acrylic acid The self-emulsifying systems showed Newtonian fluidity with viscosity closed to that of water, the solid contents were around 30% The T〓 of 15～4℃ for dried film before photocuring favored film formation at room temperature DSC and DMA results showed that PU-PETA is compatible with acrylic resin in the grafted resin The TG and dTG curves for Acr-g-PU-PETA samples were substantially different from the corresponding blends, and the brodened dTG peaks for photocured grafted resin suggest that there might be multiple interactions among chain segments The photocued film of the grafted resins self-emulsifying system exhibited good overall properties with polyurethane acrylate grafts ranging from 30% to 50%, and Acr-g-TPU-PETA series showed better properties than Acr-gPPU-PETA series The adhesion of the photocured film was 1～2 grade, impact strength was 50kg-cm and flexibility was 1mm The Shore hardness and the adhesion of the film decreased markedly if PETA was replaced by HEMA as photoactive group due to the lower C=C double bond content in the grafted resin The polyhydroxy amine-linked thioxanthones photoinitiators can be evenly dispersed in self-emulsifying system without color spot appearing in the dried film The films photocured with IV〓～IV〓 generally exhibited higher Shore hardness, gloss and solventresistance than that cured with Irgacure 2959 and did not induce the rusting of the iron substrate Pigmenting with titanium oxide had no effect on the photocuring The polyhydroxy amine-linked thioxanthone IV〓 and IV〓 can be new candidates for the formulation of titanium oxide pigmented photocurable water-borne coatings for their pale-yellow appearance and slight interference with the color of the coatings WB 4759 with high water-solubility coalesced and separated from the dried resin film, and even induced the rusting of iron substrate.

以丙烯酸丁酯，甲基丙烯酸-β-羟乙酯，丙烯酸及苯乙烯合成厂丙烯酸共聚树脂，并与含-NCO端基的聚氨酯丙烯酸酯接枝反应，经水性化后，得到两个系列（Acr-g-TPU-PETA和Acr-g-PPU-PETA）各5个不同配比的丙烯酸树脂接枝聚氨酯丙烯酸酯自乳化体系，粘度与水相近，为牛顿流体，固含量30％左右。光固化前干燥涂膜的玻璃化转变温度在-15℃～4℃之间，有利于室温下成膜。DSC及DMA谱表明两种树脂基本相容。Acr-g-PU-PETA的热失重行为明显不同于共混材料，接枝样dTG峰明显宽化，表明接枝样中链段之间的相互作刚有多重性，丙烯酸树脂与聚氨酯之间有一定的相容性。接枝树脂自乳化体系光固化涂层的综合性能以聚氨酯丙烯酸酯成分为50％～30％者相对较好，且以Acr-g-TPU-PETA系列更理想。光固化膜的附着力为1～2级，冲击强度为50kg·cm，柔软性多为1mm。以HEMA代替PETA作为接枝树脂的活性基团，碳—碳双键密度太低，光固化膜交联点太少，硬度和附着力均较差。多羟基胺连硫杂蒽酮光引发剂能均匀分散于树脂自乳化体系和接枝树脂干膜中，不出现色斑，光固化膜肖氏硬度一般高于以Irgacure 2959为光引发剂的光固化膜，光泽度及耐丁酮溶剂性能均有所提高，不会诱导铁基生锈，钛白着色对光固化结果几乎没有影响。本论文所合成的多羟基胺连硫杂蒽酮光引发剂IV〓与IV〓为浅黄色，对光固化涂层的颜色干扰较小，为配制钛白着色光固化水性涂料提供了新的光引发剂。水溶性太强的WB 4759在干膜中易聚结析出，且对所附着的铁基有诱导锈蚀作用。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。