排序方式: 共有9条查询结果,搜索用时 275 毫秒
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在Y型四能级原子系统中理论分析了外加相干控制场的强度变化对电磁感应透明和Kerr非线性效应的影响.结果发现:当外加的耦合场和抽运场的强度从相等变得不相等时,原子系统对探测场的吸收曲线从一个透明窗口逐渐变成了具有两个透明点的增益区间,透明点的位置、增益值的大小以及增益区间的宽度都与变化着的外场的拉比频率密切相关;当两个外场强度较弱并且相对强度减小时,Kerr非线性效应有所增强但同时伴随有吸收;而当两个外场的强度较强并且相对强度增大时,Kerr非线性的峰值也随之增大并且逐渐与透明点对应,即获得了无吸收巨Kerr非线性效应.研究还发现,抽运场的强度变化对Kerr非线性增强的影响作用较耦合场要大. 相似文献
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研究了级联三能级系统中孪生色锁随机光场的相位共轭阿秒和频极化拍频(ASPB)不对称新效应。从理论上分析了自关联单光子简并四波混频(DFWM)和双光子非简并四波混频(NDFWM)信号辐射场与物质间不对等效应、混合型太赫兹失谐振荡特性,及双光子非简并共振四波混频信号的延时不对称性;同时也分析了由干涉计两臂不平衡色散效应引起的阿秒和频极化拍频信号的延时不对称性,即阿秒和频极化拍频信号的最大值相对于零延时有一个小偏移,结果表明该不对称性并这不影响阿秒和频极化拍频零差探测两偶极禁戒跃迁能级分裂的总体精度。阿秒和频极化拍频作为一种消除多普勒增宽的超快调制过程,从理论上说它可以扩展到任何两偶极禁戒跃迁能级系统。 相似文献
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The near-threshold highly bound states of all three stable isotopic
variants of molecular hydrogen have been studied. Numerous
perturbations and unexpected transitions are observed as far as
1cm\sj{-1} just below the second dissociation threshold. This
complex structure may arise from a combination of nonadiabatic
coupling between B, B', C electronic states, perturbations due to
fine and hyperfine interactions, and strong shape resonances. The
perturbed near-threshold states and vibrational continuum exhibit
finegrained structure, differing greatly between isotopes because of
varying nonadiabatic coupling. 相似文献
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在表面晶格动力学理论的框架下,采用改进分析型嵌入原子法模型模拟W(100)表面沿(Γ)(L) 、(L)(M) 和(Γ)(M)对称方向上的声子色散频谱,并计算不同对称点处的极化矢量.按照表面模的判定依据和标记方法绘制不同对称方向上的表面模,并讨论表面模的分布范围和模式耦合现象.基于计算所得的极化矢量,构建近表面原子层的振动态分布,分析不同对称方向上表面模的局域特征和极化方式.以极化矢量为考察对象,直观、形象地展示了表面模色散支之间的避免交叉现象和独立性实交叉现象. 相似文献
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We propose a scheme for the enhancement of nonlinear susceptibility in a four-level tripod-type atomic system in the presence of a microwave field. With a microwave field, nonlinear susceptibility can be enhanced. Nonlinearity can also be ulteriorly enhanced by controlling the coupling field under the optimal intensity of the microwave field. The physical mechanism of the obtained giant nonlinear susceptibility is mainly based on interactions between microwave field and coupling fields. We present a physical understanding of our numerical results using a dressed-state approach and an analytical explanation. 相似文献
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