共查询到20条相似文献，搜索用时 46 毫秒
1.
张晓娟 《渭南师范学院学报》2011,26(2):14-20
采用分步傅里叶算法模拟分析了超短脉冲在三类具有不同色散曲线的光子晶体光纤中传输时的非线性传输及超连续谱产生,讨论了入射脉冲条件不同对产生超连续的影响．结果表明：相比较而言,在反常色散区形成的频谱最宽,依次是近零反常色散光子晶体光纤,同样条件下,输入脉冲位于正常色散区时频谱展宽最小． 相似文献
2.
为研究DSF光纤参量放大器(DSF-FOPA)的带宽增益特性,利用四波混频功率耦合方程进行分析,并对相位匹配条件进行了讨论.在小信号条件下,采用对称抽运时,得到了不同参数对放大器的带宽和增益的影响情况.分析结果表明,采用大的抽运功率、短的DSF光纤及宽的波长间隔可以拓宽放大器的带宽. 相似文献
3.
4.
李旸 《孝感职业技术学院学报》2006,9(2):77-79
文章比较了多模光纤和塑料光纤的结构参数和模式数量,并对大量的模式色散会严重限制光纤的带宽作了分析。根据选择性激发能够有效减少模式色散从而能提高带宽的原理,提出了一种针对塑料光纤通信的新复用技术。 相似文献
5.
6.
支鹏伟 《太原大学教育学院学报》2011,29(1):102-104
文章设计了一种基于光纤Mach-Zehnder干涉仪的声音传感器,研究了光源与光纤耦合器的基本原理和实验方法,探究了光纤偏振控制器的原理及使用方法,并利用压电陶瓷(PZT)进行光纤相位调制和解调。使用Mach-Zehnder光纤干涉声音传感器对敲击、室内走动的声响进行了测试,取得了理想的结果。 相似文献
7.
赵春 《雁北师范学院学报》2007,(6)
文章从描述超短光脉冲在光纤中传输的高阶非线性薛定谔方程入手,使用傅立叶变换的分裂算符法,通过计算机模拟,研究了高斯光脉冲在波分复用光纤系统中的传输特性.在此基础上,采用数值模拟了高斯光脉冲和超高斯光脉冲传输的稳定性以及脉冲间的相互作用. 相似文献
8.
光纤通信由于传输频带高,信息量大、保密性好、重量轻体积小,中继段长等优点得到了广泛的应用。在我国,长途网及市话传输网基本实现光纤传输。OTDR是光纤通信系统工程应用中最重要的测试仪表,光纤衰减、长度的测量、光纤接续、中继测量及故障分析等等都离不开OTDR测试。本文针对OTDR的测试和其在工程应用中常见误差分析及对策做些探讨。 相似文献
9.
本科生毕业设计"多模光纤脉冲展宽"在实践教学中的作用 总被引：1，自引：0，他引：1
结合本科生毕业设计“多模光纤脉冲展宽”的实践过程,实现了对多模光纤的材料色散、波导色散和模间色散的理论分析,使学生在有限的时间内,基本了解了M atLab应用软件,获得了光纤通信中的传输距离、工作波长、数值孔径和介质折射率对光纤色散及脉冲展宽的数值结果。在实践过程中掌握了脉冲展宽测试仪器的应用技术,获得了光源为850 nm和1310 nm,在多模光纤中传输距离为2.61 km的条件下,脉冲宽度被展宽了4.09 ns和3.07 ns和脉冲波形的变化。通过对多模光纤脉冲展宽的研究,不仅是学生完成了毕业设计论文,更重要的是在实践和科研思维能力上得到了锻炼,并发挥了学生在实践教学过程中的作用,为本科生的专业物理实验课程提供了一个新的实验项目。 相似文献
10.
In this paper, a 10 GHz radio over fiber system is analyzed. The Brillouin fiber-optic ring laser is used in the
center station (CS) to suppress the optical carrier for the modulation depth enhancement. Simultaneously, the Stockes wave
induced by the Brillouin amplification injects and locks the Fabry-Perot (FP) laser to output a signal-mode optical source,
which works as the uplink optical carrier. 相似文献
center station (CS) to suppress the optical carrier for the modulation depth enhancement. Simultaneously, the Stockes wave
induced by the Brillouin amplification injects and locks the Fabry-Perot (FP) laser to output a signal-mode optical source,
which works as the uplink optical carrier. 相似文献
11.
12.
实现了一个窄线宽36pm的Er：Yb共掺硅基光纤激光器,输出中心波长是1569．4nm.激光器的谐振腔是由一个高反的Bragg光纤光栅和另一端光纤端面4％的菲涅尔反射组成．用3．8m长的Er：Yb共掺光纤,在975m的LD激光器泵浦下,获得了最大输出功率达到6W,斜率效率达到23．5％,在输出功率范围内有明显的功率饱和现象． 相似文献
13.
A deep understanding of the spectral gain characteristics of optical parametric oscillators （OPOs） and optical parametric amplifiers （OPAs） is important for a highly efficient optical parametric conversion. We numerically calculated the spectral gain characteristics of a quasi-phase-matching （QPM） parametric conversion process using the periodically poled 6% （mol/mol） MgO doped LiNbO3 （PPMgLN） as the nonlinear crystal. In the simulation we utilized the approach of a transformative matrix of the periodically poled nonlinear medium, which results from the small-signal approximation of three-wave mixed nonlinear equations. Numerical simulation results show that： （1） The full width at half maximum （FWHM） of the spectral gain of the parametric process becomes wider with the increase of parametric wavelength and reaches the maximum at degeneration; （2） The gain coefficient decreases gradually with the increase of parametric wavelength; （3） The spectral gain bandwidth decreases correspondingly with the increase of the nonlinear material length; （4） There exists an optimal parametric wavelength band, which is most suitable for the high gain parametric conversion when pumped by a laser source with a wide wavelength band, such as the high power fiber laser. 相似文献
14.
张茂华 《安顺师范高等专科学校学报》2012,(5):132-135
由于高速和高频宽网络快速发展需要,光纤通过能够提供宽频服务逐渐成为了主要的传输媒介。光纤传播过程中不仅要确保用户收到服务的品质,最重要的是需要保证不会因为光纤断点而发生通讯中断,所以说光纤断点保护机制仍是研究的重要课题。文章通过提出一种自我治愈环型-星型光纤网络拓扑结构,尝试解决光纤网络断点问题。 相似文献
15.
Traditional methods for examining differential item functioning (DIF) in polytomously scored test items yield a single item‐level index of DIF and thus provide no information concerning which score levels are implicated in the DIF effect. To address this limitation of DIF methodology, the framework of differential step functioning (DSF) has recently been proposed, whereby measurement invariance is examined within each step underlying the polytomous response variable. The examination of DSF can provide valuable information concerning the nature of the DIF effect (i.e., is the DIF an item‐level effect or an effect isolated to specific score levels), the location of the DIF effect (i.e., precisely which score levels are manifesting the DIF effect), and the potential causes of a DIF effect (i.e., what properties of the item stem or task are potentially biasing). This article presents a didactic overview of the DSF framework and provides specific guidance and recommendations on how DSF can be used to enhance the examination of DIF in polytomous items. An example with real testing data is presented to illustrate the comprehensive information provided by a DSF analysis. 相似文献
16.
The study of measurement invariance in polytomous items that targets individual score levels is known as differential step functioning (DSF). The analysis of DSF requires the creation of a set of dichotomizations of the item response variable. There are two primary approaches for creating the set of dichotomizations to conduct a DSF analysis: the adjacent categories approach, and the cumulative approach. To date, there is limited research on how these two approaches compare within the context of DSF, particularly as applied to a real data set. This study evaluated the results of a DSF analysis using both dichotomization schemes in order to determine if the two approaches yield similar results. The results revealed that the two approaches generally led to consistent results, particularly in the case where DSF effects were negligible. However, when significant DSF effects were present, the two approaches occasionally led to differing conclusions. 相似文献
17.
The chromatic dispersion( CD) degrades themodulation-phase relationships of lightwave signals,reducing information-carrying capacity through pulse-broadening in digital networks and distortion in analogsystems[1,2]. The widespread use of dense wavelengthd… 相似文献
18.
The assessment of differential item functioning (DIF) in polytomous items addresses between-group differences in measurement properties at the item level, but typically does not inform which score levels may be involved in the DIF effect. The framework of differential step functioning (DSF) addresses this issue by examining between-group differences in the measurement properties at each step underlying the polytomous response variable. The pattern of the DSF effects across the steps of the polytomous response variable can assume several different forms, and the different forms can have different implications for the sensitivity of DIF detection and the final interpretation of the causes of the DIF effect. In this article we propose a taxonomy of DSF forms, establish guidelines for using the form of DSF to help target and guide item content review and item revision, and provide procedural rules for using the frameworks of DSF and DIF in tandem to yield a comprehensive assessment of between-group measurement equivalence in polytomous items. 相似文献
19.
对短脉冲光纤激光器锁模的物理机制加以理论研究，由光脉冲传输方程理论推证得出光纤激光器和主动锁模激光器的理论模型，从而得出孤子效应在主动锁模技术中影响锁模的稳定性。 相似文献
20.
A novel quantum dots (QDs) optical fiber amplifier was proposed and demonstrated. It was fabricated by dipcoating the PbSe
QDs doped sol onto the taper region of fiber coupler. The PbSe QDs was synthesized according to a colloidal method. A lower
refractive index sol was also synthesized as the host of PbSe QDs. A standard single mode fiber was used to make the fusion
tapered fiber coupler which had double input and output ports. With the simple structure, a signal and a pump can be injected
into the amplifier and excite the PbSe QDs through evanescent wave. The experimental results indicated that the amplified
light wave was observed at 1 550 nm wavelength with 980 nm wavelength laser diode as pump. 相似文献