共查询到20条相似文献，搜索用时 171 毫秒
1.
罗青 《赣南师范学院学报》2005,26(6):13-16
对在光纤中反向传输的两束光,以包含了三、四阶色散项的耦合非线性薛定谔方程为基础,主要研究高阶色散对交叉相位调制不稳定性的影响.三阶色散对调制不稳定性不起作用,但反向传输光的群速度却对不稳定性的发生有影响;当满足一定条件时,由于四阶色散的影响,在光纤的反常色散区,交叉相位调制不稳定性发生在两个频谱区.在正常色散区,四阶色散产生了一个新的交叉相位调制不稳定性频谱区;反常色散区远离零点的频谱区的增益谱比正常色散区的增益谱更靠近零点,且两个频谱区的范围有准分离的对称关系. 相似文献
2.
罗青 《南京晓庄学院学报》2010,26(3):27-30
利用广义非线性薛定谔方程,研究了零色散光纤中交叉相位调制不稳定性,分析了高阶色散和高阶非线性系数对增益谱的影响.发现当光脉冲工作在零色散附近时,交叉相位调制不稳定性主要取决于四阶色散,它使增益谱变宽.正五阶非线性使增益谱的谱宽和峰值增大,负五阶非线性使增益谱的谱宽和峰值减小. 相似文献
3.
罗青 《南京晓庄学院学报》2006,22(6):11-15
从包含高阶色散项的广义非线性薛定谔方程出发,得到了描述交叉相位调制(XPM)不稳定色散方程的一般表达式,研究了四种不同情况下调制不稳定的增益频谱特性.结果表明:由于四阶色散的影响,单光束传输时,在光纤的反常色散区出现一个新的调制不稳定频谱区;双光束传输时,在普通光纤和色散缓变光纤(DDF)的正常和反常色散区,XPM不稳定均发生在两个频谱区. 相似文献
4.
利用修正的非线性Schrodinger方程研究了单模光纤中零色散波长附近飞秒光脉冲的调制不稳定性，发现了一个新的由光纤四阶色散导致的调制不稳定区域，新区域的最大调制增长率和调制范围与光脉冲的初始入射功率和四阶色散有关．光纤自陡峭效应和Raman延迟效应对两个调制不稳定区域的最大调制增长率和调制范围都有影响，自陡峭效应对新区域的影响较大且存在一个决定新区域出现与否的阈值；Raman延迟效应对调制不稳定性的影响比自陡峭效应显著，尤其当Raman延迟效应较强对，它使两个区域合并成一个具有更大调制范围的调制不稳定区域。 相似文献
5.
刘小龙 《吕梁高等专科学校学报》2009,25(1)
主要研究了不同群色散剖面色散缓变光纤(DDF)中脉冲传输的展宽因子,并将DDF展宽特性的仿真结果与单模光纤(SMF)进行对比;另外分析了二阶色散以及高阶非线性效应在DDF中产生的调制不稳定性,从而对DDF做了一个较为全面的分析. 相似文献
6.
吴粤湘 《深圳职业技术学院学报》2012,11(3):3-6
利用数值求解非线性耦合方程,研究了四阶色散对于单泵浦光纤参量放大器增益的影响．计算表明,通过优化泵浦波长和四阶色散值,可以获得大的平坦带宽或者特殊的应用．分析了在大信号输入时对应增益的变化,发现对于泵浦波长大于零色散波长且四阶色散为正值的增益谱影响最大． 相似文献
7.
单模光纤的色散和损耗特性测量系统 总被引：1，自引：1，他引：0
光纤的色散引起传输信号的畸变,而损耗则引起光能的衰减,因此色散和损耗在很大程度上决定了光传输系统的通信容量和中继距离.目前长距离、大容量光纤通信系统中多采用单模光纤,故测量单模光纤的色散和损耗特性非常重要.简要分析了光纤的色散和损耗的概念,然后分别介绍了用相位移法和插入法测量单模光纤的色散和损耗的实验方法与系统.该实验系统可以同时满足单模光纤的色散和损耗特性测量需要,设备简单、集成度高、成本低、操作简便. 相似文献
8.
高的频带效率和能量效率,与先进调制方式相干检测技术有机地结合,针对下一代高速光通信网络而言,已经是比较有前途的技术.将电子技术领域中的数字信号处理功能有效地利用,无论对于偏振模色散和色度色散,还是光纤非线性效应和激光相位噪声等相关的传输损耗,相干光接收机都能够给予良好补偿. 相似文献
9.
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
10.
初始啁啾对光脉冲传输的影响 总被引：2，自引：0，他引：2
从理论上分析了正常色散区域中群速度色散(GVD)和自相位调制度效应(SPM)对光纤中光脉冲传输的影响，结果表明负初始啁啾脉冲在传输过程中能够得到压缩，正初始啁啾导致啁啾脉冲频谱展宽，自相位调制也能使光脉冲压缩但效果较差。 相似文献
11.
罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
12.
邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
13.
Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
14.
Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
18.
Rachel Zupek 《海外英语》2007,(11):40-41
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了 相似文献
19.
陈美曦 《山东教育学院学报》2008,23(2):103-107
Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language. 相似文献
20.
《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献