查询词典 grating

To meet the needs, a novel low-noise fiber laser with compound cavity structure is designed. The stable single-mode operation is realized by using a transient self-written fiber grating, produced by the effect of saturable absorption within a section of unpumped erbium-doped fiber, as narrow band filter for mode selecting and linewidth squeezing. Through optical path modification, the spectral signal-to-noise ratio is better than 62 dB.

激光器采用复合腔结构，以掺铒光纤作为工作物质，通过在未被抽运的掺铒光纤中形成的瞬态自写入光纤光栅的窄带滤波特性进行选模和压窄线宽，产生稳定的单频激光输出；经过光路改进，激光输出光谱信噪比优于62 dB；利用光电负反馈电路，弛豫振荡峰下降了约25 dB，低频段强度噪声也大为改善，有效地抑制了光源的强度噪声。

A single-longitudinal mode fiber laser with fiber saturable absorber is designed. Tunable fiber Bragg grating as the wavelength selector is in the ring cavity with a 2 m-long unpumped erbium-doped fiber.

设计了一种基于光纤饱和吸收效应的环形单纵模光纤激光器结构，以可调谐光纤布拉格光栅作为波长选择器件，与2 m未抽运掺铒光纤一起位于环形腔反射臂上。

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。

The function of 3dB fiber loop mirror in fine wavelength partition is studied. With this theory, a novel narrow linear band, dual-wavelength switchable Er-doped fiber laser is realized.2. An unpumped Er-doped fiber and broadband fiber Bragg grating with high reflectivity is served as an auto-tracking filter, where the space hole-burning effect appears when the laser signal travels and forms standing wave, thus the generation of multi-longitudinal-mode is suppressed. Then the high birefringence fiber loop mirror is introduced to act as comb-liked wavelength filter.

主要包括：1、发现3dB光纤环镜的精细波长分割作用，并利用这种分割机制，研制成功一种窄线宽、双波长可转换的掺铒光纤激光器。2、利用未受泵浦的掺铒光纤以及宽带高反射率的光纤布喇格光栅做自动跟踪滤波器，当穿行其中的激光信号构成驻波时，出现了空间烧孔效应，从而抑制了多纵模的产生，引入高双折射光纤环镜做梳状波长滤波器。

To realize single longitudinal-mode of the fiber laser, a ring configuration is devised. The single longitudinal-mode operation is realized by using a fiber Bragg grating as wavelength-selective element and a unpumped 2m-loog erbium-doped fiber which can produce stading-wave saturation effects in the cavity, Its tunable wavelength range is 42 nm, the output power is more than 3.5 dBm and the stability is less than ±0.005 dB.

为了实现光纤激光的单纵模，提出了一种环形腔结构，采用可调谐光纤Bragg光栅作为波长选择器件，与2m未抽运掺Er光纤产生驻波饱和效应，在1.55m波长处形成42nm激光输出，输出功率大于3.5dBm，功率稳定性优于士0.005dB。

Only an arbitrary single pulse among pulse train with temporal separation of about 1 ps was trapped by soliton pulse,the trapped pulse was blue-shifted and the optical spectra of trapped pulse was distinctly separated from those of the untrapped signal pulses.The trapped pulse can be easily picked off using a wavelength filter such as a fiber Bragg grating.

通过数值求解光子晶体光纤中脉冲传播满足的耦合非线性薛定谔方程，发现用孤子脉冲可俘获信号脉冲串中的任何一个脉冲，被俘获的信号脉冲的中心波长明显蓝移，在频域上和其他信号脉冲分离开来，于是让信号脉冲串在输出端通过布喇格光纤光栅，被俘获的信号脉冲将被过滤掉。

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。

In addition, the analytic expression of peak value of PER associated with the length of grating, the modulation depth of refractive index and the Verdet constant is also given, with convenient application to the performance analysis of magnetic field measurement.

文章还给出了峰值消光比与光栅长度、折射率调制深度和费尔德常数之间关系的解析式，可方便地用于分析磁场的测量性能。

We review the dark decay of the electronic holographic phase grating before thermal fixing, and deduce the general analytic expression of the lifetime of thermal-fixed ionic holograms in the photorefractive crystal, by means of analogizing.

通过类比的方法，由热固定前的电子体全息相位栅的暗衰减得出了热固定后离子体全息光栅的衰减规律及其寿命的一般解析表达式。

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。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了