双泵浦光纤参量放大器中泵浦与光纤长度选取的研究

研究了强非线性色散位移光纤和光子晶体光纤中的光纤参量放大增益特性.结果表明,在泵浦光功率低于受激布里渊散射阈值的条件下,当两泵浦光功率相等且功率之和与光纤长度的乘积满足某一特定值时,可得到最佳增益谱平坦性、增益峰值、增益带宽等参数;适当改变光纤长度或泵浦光功率,可以优化光纤参量放大.     

铒镱共掺光波导放大器增益特性模拟和性能优化

在分析铒镱共掺系统的能级结构和相关跃迁的基础上,根据速率方程和传输方程,建立了EY-CDWA的增益模型,给出了EY-CDWA的增益公式,对增益特性进行了模拟,并对影响放大器增益的波导长度及泵浦功率等相关条件进行了优化.模拟计算中建立了参数优化方案,实现了放大器泵浦波长、泵浦功率和增益的同步优化,得到最佳长度下的最大增益,该理论模型应用于实际制作的Yb-Er共掺Al2O3光波导放大器.结果与实验数据相符.     

掺铒光纤放大器的特性研究

从理论和实验两方面研究了掺铒光纤放大器的输出特性。在理论上用数值模拟的方法研究了泵浦功率、信号光强度、光纤长度等参数的变化对输出特性的影响。通过实验研究了泵浦光源的输出功率和驱动电流的关系、放大器的增益与泵浦功率和输入信号光功率的关系。研究表明实验结果和数值模拟结果相吻合,对掺铒光纤放大器的结构设计,以及改善掺铒光纤放大器的增益特性有一定的指导作用。     

泵浦功率对C波段EDFA增益斜率的影响

基于C波段掺铒光纤放大器(EDFA)的增益斜率随泵浦功率变化的实验现象,研究了不同泵浦功率对增益斜率的影响,从理论上对实验现象进行了解释.然后用OptiSystem 模拟不同泵浦功率下的EDFA增益谱,结果与实验室增益斜率数据相一致.     

掺镱光纤放大器中受激拉曼散射的数值分析

采用描述泵浦光、信号光和Stokes光的稳态速率方程组,对不同光纤参数及泵浦光参数下掺镱光纤放大器内的泵浦光、信号光以及Stokes光沿光纤轴向的演化进行了数值分析.结果表明:受激拉曼散射的发生会导致信号功率在达到增益饱和之前迅速下降;增大泵浦功率,采用掺杂浓度较高的掺镱光纤以及较大吸收截面的泵浦光可以在较短光纤内获得较好的信号放大而避免受激拉曼散射的发生.     

掺Er3+Al2O3平面光波导放大器理论计算

利用速率方程模型,通过求稳态解,比较了1480、980、820nm3种波长泵浦时的掺Er^3 Al2O3平面光波导放大器的增益与泵浦功率和掺铒浓度的关系。在确定的泵浦功率下,存在最佳掺铒浓度,可得到最大增益,并且泵浦功率增大,最佳掺铒浓度也增大。同时分析了激发态吸收和合作上转换对增益的影响;高功率泵浦时,激发态吸收对增益的影响明显,高浓度Er^3 时,合作上转换对增益的影响显著,并提高了放大器阈值泵浦功率。     

线形和复合腔结构布里渊光纤激光器实验研究

文章通过实验研究了基于线形腔和复合腔结构的布里渊掺铒混合增益光纤激光器的输出特性。采用1 km单模石英光纤作为布里渊增益介质,研究了该布里渊激光器的输出特性参数与泵浦波长、泵浦功率、腔型结构等因素的关系。通过实验分析,得出线形腔和复合腔2种结构在不同布里渊泵浦波长条件下产生一阶斯托克斯光时的1 480 nm激光器的阈值泵浦功率,并研究了高阶斯托克斯光输出随1 480 nm激光器泵浦功率的变化情况;布里渊波长从1 540 nm变化到1 570 nm时,线形腔和复合腔阈值泵浦功率分别在139～172 mW及196～294 mW范围变化;保持1 480 nm激光器泵浦功率为623 mW,增大布里渊泵浦功率,2种结构都获得了最多达到10个波长的稳定激光输出。     

高功率LD侧面泵浦Nd：YAG激光器四镜折叠腔分析与设计

运用ABCD传输矩阵理论，把增益介质作为类透镜处理，对LD侧面泵浦地Nd：YAG激光器四镜折叠腔进行了分析。特别讨论了增益介质内部基模光斑半径和基模体积随泵浦功率变化的关系．在此基础上得到了一组腔的优化参数，能使激光器实现大基模体积热稳运转，并很好地补偿了像散．     

高功率LD侧面泵浦Nd:YAG激光器四镜折叠腔分析与设计

运用ABCD传输矩阵理论,把增益介质作为类透镜处理,对LD侧面泵浦地Nd:YAG激光器四镜折叠腔进行了分析,特别讨论了增益介质内部基模光斑半径和基模体积随泵浦功率变化的关系.在此基础上得到了一组腔的优化参数,能使激光器实现大基模体积热稳运转,并很好地补偿了像散.     

飞秒激光参数对三态梯度型分子态布居数的影响

 利用含时波包法研究并且首次量化了强飞秒泵浦-探测激光场中泵浦场强、泵浦波长和脉宽对三态梯度型K₂分子态布居数的影响。泵浦场强、泵浦波长和脉宽影响Rabi振荡,而Rabi振荡的变化又导致了基态和激发态布居数周期性变化。量化这3个激光场参数对激发态布居数的影响验证了此周期性变化规律,表明变化频率随着泵浦场强和脉宽的增大而变化。研究表明调节激光场参数可实现对态布居数的选择性分布,可以为实验上实现分子的光控制提供重要参考。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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