光栅

Presented the settle means of Fiber Bragg Grating sensor's cross-talking problem or simultaneously measu- ring of temperature and strain. Introduced some main problems of Fiber Bragg Grating senso- rs that needed to be solved when it's applied in practical use.

提供了光纤光栅传感器在温度和应变测量中交叉敏感问题的解决办法，介绍了光纤光栅传感器在实际应用中需要解决的几个主要问题。

In order to study the effect of microstructure on the superhydrophobic solid surface for its drag reduction charactertics, micro-ridges grating structures on the basis of K9 glass flat surface were fabricated using femtosecond laser. Experiments were carried out to measure the rheological characterization of 40% glycerin solution on flat and grating structured K9 glass surfaces using AR-G2 rheometer respectively. Both surfaces were modified with trichloro perfluoroocty silane in drying oven.

为了研究超疏水固体表面的微结构对减阻特性的影响，首先利用飞秒激光加工技术在光滑K9玻璃基面上加工出微脊光栅结构，然后将光滑K9玻璃与光栅结构K9玻璃置于干燥箱内进行硅烷化处理，以降低表面自由能，最后用AR-G2流变仪测量两表面的流变特性，试验用流体为体积分数40%的甘油溶液和水。

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。

Spatial holeburning caused by ununiform widening of erbiumdoped fiber barricades the fully gaincontrolled amplification of laser with single wavelength. A novel configuration of automatic gainclamped optical erbiumdoped fiber amplifier is presented, and a high-birefringence fiber Bragg grating is used to generate pumping lasers, peaks of which are written at 1549.3 nm and 1549.83 nm with a wavelength spacing of 0.53 nm.

掺铒光纤非均匀展宽引起的空间烧孔现象导致单波长激光并不能完全控制放大器增益，提出了一种新颖的自动增益控制掺铒光纤放大器的结构：即采用高双折射光纤布拉格光栅产生抽运光，其写制光栅的波峰对应的波长分别为1549.3 nm和1549.83 nm，波长间隔为0.53 nm。

Fiber grating coupler has good wavelength selection characteristic of optical fiber grating as well as multiport advantage of fiber coupler. These features make it easy to realize allfiber optical add/drop multiplex.

光纤光栅耦合器具有光纤光栅良好的波长选择特性和光纤耦合器的多端口特点，易于实现全光纤的光波分插复用。

A simple and novel method for transforming a uniform fiber grating into a linearly chirped grating is presented.

报道一个简单而新颖的、能将均匀光栅改变为线性啁啾光栅的方法。

In this paper,we introduced the progress of chirped fiber grating and its application in optical communication field and sensor field.

文章简要介绍了Chirped光纤光栅的制作方法与传感应用，分析了Chirped光纤光栅的调谐原理和调谐性能。

Based on the filter characteristic of long-period grating, the wavelength-change of sensing grating can be demodulated.

为简化信号解调方法，利用长周期光纤光栅的边沿滤波器特性，实现光纤光栅传感波长的解调。

Signal demodulating technology of Fiber Bragg Grating sensing system is one of critical factors which limit the development of FBG sensing technology.

光纤光栅传感信号的解调技术是制约着光纤光栅传感技术发展的关键因素之一。

The thesis indicates that grating is a diffractive element, when the diffraction elements diffracts light into the solar cell, and the diffractive grating can be reflected due to its diffractive feature.

研究中所使用的光栅为一个绕射元件，在太阳能电池上制作一个绕射光栅，这个绕射元件可以将太阳光直接穿透至太阳能电池，并且也可以从太阳能电池反射的太阳能，进一步的进行再利用。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。