光栅

One of the important tasks in Resin Transfer Molding is the selection of appropriate processing parameters, so that the mold cavity will be filled completely and the composite quality can be guaranteed. Successful completion of these tasks requires knowledge of the resin flow, especially the resin flow front profiles, the pressure distribution, temperature distribution and the resin conversion distribution et al. In this paper, the governing equations of resin flow are presented on the base of the seepage mechanics, the thermodynamics and the chemical kinetics. The unlumped temperature system i.

中文题名树脂传递模塑工艺过程数值模拟与固化过程监测研究副题名外文题名 Investigation on numerical simulation and curing process monitoring of resin transfer molding 论文作者李海晨导师王彪教授学科专业工程力学研究领域\研究方向学位级别博士学位授予单位哈尔滨工业大学学位授予日期2002 论文页码总数10，121页关键词树脂固化光栅树脂传递模塑复合材料馆藏号BSLW /2003 /TQ320 /7 树脂传递模塑(Resin Transfer Molding，RTM)工艺过程研究的主要任务之一是选择合适的工艺参数，以使树脂充分润湿增强纤维，保证固化后产品质量。

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。

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。

For lightly doped unreduced crystals, the thermal fixing efficiency up to 50% has been achieved.

实验表明热固定效率和光栅的暗存储寿命不能同时提高，这与理论预期一致。

For lightly doped unreduced crystals, the thermal ...

实验表明热固定效率和光栅的暗存储寿命不能同时提高，这与理论预期一致。

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。

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。

According to different temperature, potential of reducing gas and content of SiO〓 in concentrate iron will be separated out in whiskery, thick and porous structure.

本文通过光栅电子显微镜对水平管状炉和石英管流化床还原试样的显微结构分析，研究了多种铁精矿在还原过程中铁的析出形态及其与粘结行为的关系。

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。