倒Y-型原子系统中增益辅助的慢光研究

通过外加驱动场并使其与四能级原子系统能级共振,能够改变四能级原子系统中的色散和吸收特性。研究表明,选择适当的参数,探测光场可被放大,即有增益产生。同时,探测光场增益-吸收系数表现为增益。这种现象正好和探测光场的慢光现象对应起来,即增益辅助的慢光。这样,在该种原子系统中,可以达到对探测光场有效观测的目的。而这种慢光传输的现象在高保真光纤延迟线和现代光学信息处理方面有潜在的应用价值。     

铷原子超精细谱线的强度差异机理研究

为了理解相同实验条件下铷原子的超精细吸收谱线的强度差异形成的机理,以~(87)Rb-D_2线F=2为工作物质,从实验上获得了6条明显的超精细饱和吸收谱对应的实验参数,将其用于理论计算.理论计算中考虑了超精细能级之间跃迁的相对强度因子、与原子团速度有关的有效原子数密度以及光泵浦效应导致的自发衰减率,计算得出的饱和吸收谱与实验结果相吻合.结果表明,共振主峰强度差异主要源于跃迁强度因子和光泵浦效应因子的不同,交叉共振峰强度差异主要原因是跃迁强度因子、有效原子数密度和光泵浦效应因子不同造成的,而交叉峰强于主峰源于交叉峰是由速度相反的两部分原子团共同作用产生的.     

基于铷饱和吸收光谱分析谱线频移的频率标尺

针对示波器接受光电信号时,横坐标显示的是扫描时间,不能直接分析信号频移量的问题,设计了铷原子的饱和吸收光谱实验,并在示波器上同步接收法布里-珀罗腔的干涉条纹和铷原子D2线的饱和吸收谱线信号.利用实验上观测到的87 Rb D2线F=2的6个饱和吸收峰和已知的铷原子超精细能级结构确定频率标尺,计算了85 Rb D2线吸收峰之间的频率差及法布里-珀罗干涉条纹的自由光谱范围.结果表明,实验上确定的频率标尺与理论相符,饱和吸收光谱可用于标定基态到激发态跃迁谱线的频移量,而通过饱和吸收光谱计算得到的自由光谱范围则可作为激发态能级跃迁的频率标尺,分析激发态能级跃迁的频移.     

整形啁啾脉冲作用下的双光子跃迁几率增强效应

基于二阶微扰理论,分析了整形啁啾脉冲作用于原子系统的双光子过程.研究了在远离共振和近共振两种情况下啁啾脉冲光场作用时双光子跃迁几率的演化规律.结果表明:远离共振时,利用整形光脉冲作用于原子系统,会使得某些频率对应处的跃迁几率消失,光可以无损耗通过介质;近共振时,选择最佳相位函数对脉冲整形,可获得最大的双光子跃迁几率.     

简并二能级系统中的正负色散(英文)

通过解光学布洛赫方程,考察了简并二能级系统的吸收色散性质。采用一束平行线偏振光(π)泵浦和一束横向线偏振光(σ±)探测,在有磁场的情况下简并被破坏,改变耦合光强时发现了失谐零点正负色散之间的转化,这样我们就得到了慢光速与超光速之间的转变。在其它泵探光场偏振情况下同样有正负色散变化,它普遍存在于简并能级系统中。同时我们还发现了吸收谱中的电磁诱导透明、电磁诱导吸收、Mollow吸收谱型等现象。     

掺Yb~(+3)光纤的光学双稳与多稳的相干控制研究

Yb+3具有简单的二能级结构,利用双光子驱动建立起原子的相干,由于Yb+3的能级具有上下多重态的结构特点,使原子跃迁在多个Stark子能级间发生.这些跃迁的相干叠加决定着介质的非线性吸收和色散,而相干叠加的结果取决于驱动场的拉比频率.结果表明通过改变驱动场的拉比频率,可有效控制系统的双稳与多稳的存在与否和阈值强度的高低.     

Cs法拉第反常色散光学滤波应用于边缘滤波器特性分析

提出将Cs法拉第反常色散光学滤波应用于边缘滤波器,以弥补利用127I2和129I2分子的共振跃迁实现分子边缘滤波器的不足.对Cs 6S1/27P1/2法拉第反常色散谱的滤波特性、频率调谐特性进行了理论分析.结果表明:Cs原子的法拉第反常色散谱对称地存在2个陡的线翼透射峰,通过调节气室温度和外加磁场强度,线翼透射峰中心频率可以被调节到适当的位置,以满足边缘滤波器的实际需要.     

Ladder型介质中双色超短脉冲共振传播的RCEP控制

利用不含慢变振幅近似(SVEA)和旋波近似(RWA)的全波Maxwell-Bloch方程组的数值解,研究了单光子共振(即两个脉冲的中心频率分别与原子系统两个跃迁频率相等)情况中,在ladder型三能级原子介质中双色超短激光脉冲传播行为对相对载波包络位相(RCEP,以下简称相对位相)的依赖性.结果表明:相对位相对小面积双色脉冲的传播波形及频谱特性有显著的控制作用.相对位相的大小可以决定脉冲振幅大小、传播速度快慢、脉冲分裂与否及子脉冲数目多少.通过改变相对位相的数值可以获得更宽的频谱宽度及更高的光谱强度特别是高频分量的光谱强度.当双色脉冲面积增大时,相对位相对脉冲波形及频谱特性的控制作用有所减弱.     

电磁诱导吸收的研究进展

电磁诱导吸收是光与物质相互作用中表现出来的奇特的非线性效应,对其形成机理及非线性特性的研究具有重要的理论意义和巨大的潜在应用价值.本工作以简并二能级、N型四能级系统和近似简并的Λ型能级系统的研究结果为基础,探讨了电磁诱导吸收的产生条件和本质.结果表明,原子相干对吸收的相长干涉产生电磁诱导吸收,而且其色散谱线在对应频率位置出现了变化剧烈的反常色散,可以引起探测光的群速增快甚至出现负群速,其应用前景正在进一步研究中.     

奇偶纠缠相干态光场驱动下Λ-型三能级原子的辐射谱

采用时间演化算符方法,研究Λ-型三能级原子与奇偶纠缠相干态光场共振相互作用的辐射谱.给出了辐射谱一般公式.结果表明:不论下能级简并与否,奇偶纠缠相干态光场平均光子数很小时均出现拉比分裂,且下能级简并时,强度随奇偶纠缠相干态光场纠缠程度的增加而增加;两下能级非简并时,一模场驱动的辐射谱峰高随纠缠程度的增加而增加,而另一模场驱动的辐射谱峰高随纠缠程度的增加而减小.一般辐射谱呈对称的10蜂结构.     

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.     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

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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