共查询到20条相似文献,搜索用时 50 毫秒
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针对拉曼驱动场下的四能级理论模型,讨论了实现无吸收、高折射率的条件,并分析了探测场及相干激发场的线宽对介质的折射率及增益的影响。计算结果表明,改变相干激发场 场强,或改变相干场的频率与原子能级间的失谐均可获得介质的无吸收,高折射率。激发扬线宽破坏了原子的相干性,使使介质的增闪下降并改变了折射率的大小,探测场的线宽使介质的探测增益谱及折射率谱的分辨率下降。 相似文献
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针对喇曼场驱动下的四能级理论模型,讨论了光场的空间横向效应对无粒子数反转光放大增益的影响.计算结果表明:光场的空间横向效应使探测场的探测谱形状发生了变化;为了在样品池的出口处获得较高增益,汇聚透镜的最佳聚焦位置不应在样品池的中心,而应在样品池的出口附近.关键词: 相似文献
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高Q Kerr介质腔中光场相位自调制效应对原子布居的影响 总被引:1,自引:0,他引:1
研究了高Q kerr介质腔中的二能级原子与双模光场相互作用系统中,光场的相位自调制效应对原子布居的影响. 研究发现随着相位自调制强度的增加, 原子与光场的耦合减弱,并证明光场相位自调制强度与光场的各模有关. 同时分析讨论了光子数对原子布居的影响. 相似文献
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利用含时波包法研究了强飞秒泵浦-探测激光场中激光脉宽对非绝热耦合NaI分子波包运动的影响.发现波包的振荡周期随脉宽增长而增大,而振荡幅度随脉宽增长而减小.非绝热效应引起的波包在交叉区域的分裂情况影响各态布居.脉宽增长,NaI分子的激发概率增大,而解离概率减小.研究表明调节激光场脉宽可实现对波包运动的控制从而控制态布居的选择性分布.研究结果可以为实验上实现分子的光控制以及量子调控过程提供一定的参考. 相似文献
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为探讨调频场导致的量子效应的物理本质,运用密度矩阵方程和布洛赫矢量模型,对调频场作用下二能级原子系统中的粒子布居几率振荡现象进行了理论分析,讨论了光场调制振幅对振荡过程的影响。理论计算结果表明,光场调制振幅对粒子布居转移和几率振荡有较大的调制作用。当其他参量不变时,随着调制振幅的增大,粒子布居几率振荡减弱,布居转移效率增高,吸收增强。布洛赫矢量分析表明,该振荡过程是系统粒子数转移、吸收和极化三者之间的动态变化过程。 相似文献
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在量子信息的研究中,量子Zeno效应(QZE)的研究对量子信息的处理有重要作用.针对原子—场相互作用系统,在Jaynes Cummings ( JC) 模型下,研究在不同测量时间间隔中, 布居翻转与初态存活概率的变化趋势.同时得出在时间间隔足够小时,产生QZE,进而得出QZE对布居翻转的影响. 相似文献
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模拟研究了光场极化方向对自由电子与线偏振强激光束间发生净能量交换(非弹性散射及加速效应)的影响.研究结果表明,当光场强度0.1a01时(a0=eE0/mecω),电子在激光束上的散射呈现弱的非弹性效应,且与场的线偏振极化方向无关,表现为空间各向同性,与有质动力势模型的结果定性一致.而当a010时,电子与光场间的净能量交换不仅变得明显,而且依赖于电子入射方向与场极化面之间的夹角.当电子沿电场极化面入射时,净能量交换效应最显著,随着这一夹角的增大,这一效应逐渐减弱乃至消失.此时电子在强光束上的散射表现出明显的空间各向异性,有质动力势模型已完全不再适用. 相似文献
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The time-dependent wave packet method is used to investigate the influence of laser-fields on the vibrational population of molecules.For a two-state system in laser fields,the populations on different vibrational levels of the upper and lower electronic states are given by wavefunctions obtained by solving the Schro¨dinger equation with the splitoperator method.The calculation shows that the field parameters,such as intensity,wavelength,duration,and delay time etc.can have different influences on the vibrational population.By varying the laser parameters appropriately one can control the evolution of wave packet and so the vibrational population in each state,which will benefit the light manipulation of atomic and molecular processes. 相似文献
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Employing the two-state model and the time-dependent wavepacket method, we have investigated the influences of the parameters of the intensefemtosecond laser field on the evolution of the wave packet, as wellas the population of ground and double-minimum electronic states ofthe NaRb molecule. For the different laser wavelengths, the evolution ofthe wave packet of 6{ }^1Sigma ^ + state with time andinternuclear distance is different, and the different laserintensity brings different influences on the population of theelectronic states of the NaRb molecule. One can control the evolutionsof wave packet and the population in each state by varying the laserparameters appropriately, which will be a benefit for the lightmanipulation of atomic and molecular processes. 相似文献
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Using the three-state model and time-dependent wavepacket method, the influence of the parameters of the intense femtosecond laser field on the wavepacket dynamic process of the double-minimum potential state 51Σ+ and the population of the ground and diabatic electronic states of NaLi are investigated. The calculations show that different femtosecond laser parameters result in different influences on the evolution of the wavepacket and the population of NaLi. With increasing laser intensity and wavelength the diabatic coupling strength between A and B states first strengthens and then weakens. The population interchanges between A and B states when the laser pulse disappears. The above results provide the suggestions and useful information for one to achieve quantum manipulation of the molecule in an experiment. 相似文献
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This paper presents calculation results for the photoassociation of a NaK molecule with a two-color modulated laser and gives a detailed analysis about them.For the two-step photoassociation process in intense fields,the effect of two-color modulated laser parameters,such as relative phase,envelope period,and laser intensity,on the population of the molecular electronic state can be obtained by solving the time-dependent Schrodinger equation through the quantum wave packet method.The numerical simulation shows not only that the influence of laser parameters on the vibrational distribution presents some regularity,but also that a higher population in the ground electronic state can be realized through adjusting these laser parameters. 相似文献
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强激光非线性条件下分子的多光子电离过程呈现出较为明显的强场效应.由于这种效应不能用传统的量子微扰论来处理,“缀饰态”模型方法提供了物理图象清晰的处理光与物质相互作用的方案.本文基于含时波包动力学的基本理论,将激光场看作经典场,利用“缀饰态”模型研究了强场下双原子分子(NO、RbI等)的多光子电离过程.研究表明,激光场的强度、泵浦-探测脉冲延迟时间等对多光子电离光电子能谱的形状有着重要的影响,而这种影响是由光诱导势引起的.另外,在研究具有两个连续态的RbI体系时,自电离现象的发生也与势能面的交叉密切相关,并受外场强度的影响.本文计算模拟外场中分子的光电子能谱时所得到的强场效应对理解和实现原子分子过程的激光操控具有重要的意义. 相似文献
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采用含时量子波包方法研究基电子态HeH+体系优化的光缔合几率,即He+H+→HeH+随碰撞粒子对初始动量的变化,并研究伴随该过程的多光子跃迁和解离.选取v=6振动能级为目标态,通过优化激光场参数得到碰撞粒子对的最优光缔合几率.结果表明:随着碰撞粒子对初始动量的增加,光缔合所用的最优激光场的持续时间逐渐减少,但光场的强度和失谐逐渐增加.在某些初始碰撞动量附近,由于共振多光子跃迁过程的存在,最优的光场不能严格地将碰撞粒子对缔合到目标态.此外,研究表明随着初始动量的增加,系统的超阈值解离几率近似线性地增加到一个最大值,直至饱和强度.并且,在碰撞粒子对的初始动量较大时,超阈值解离主导解离过程. 相似文献
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通过对光与物质相互作用产生的各种效应的研究可以获得物质的组分、结构、电学、力学、相互作用等信息,因此光学激发和探测技术成为现代科学研究的重要工具。然而衍射效应将光学探测的最小空间尺度约束在波长量级,这严重限制了光学对微观结构的探测。近年来基于扫描探针显微镜发展而来的近场光学显微镜利用光学天线对光场的局域和增强作用,将光学探测的分辨率推进到10 nm的尺度。文章将介绍目前一种主流的光学超分辨技术——散射式扫描近场光学显微镜及其在材料科学和生命科学方面的前沿研究进展。 相似文献
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Photonic spin-orbit interactions (PSOIs) in nanostructures have attracted much interest in nanophotonics, which provide a new paradigm to enhance light-matter interactions and engineer the wavefronts of light on demand at the nanoscale. Many striking phenomena and functionalities, such as the photonic (quantum) spin-Hall effect and the spin-vortex conversion, have been demonstrated. Besides their underlying physics and manifestations, the experimental probing and imaging of PSOIs are also of great importance and highly demanded in not only the fundamental research but also the development of emerging PSOI technologies. Hence, in this review, the state-of-the-art studies on the experimental observations and detections of PSOIs are systematically reviewed, including both the far-field and near-field methods. The respective advantages and difficulties of each method are stated and analyzed. The perspectives in probing PSOIs are also discussed. 相似文献
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Our recent efforts in manipulating electromagnetic (EM) waves using metamaterials (MTMs) are reviewed with em- phasis on 1) manipulating wave polarization and transporting properties using homogeneous MTMs, 2) manipulating surface-wave properties using plasmonic MTMs, and 3) bridging propagating and surface waves using inhomogeneous meta-surfaces. For all these topics, we first illustrate the physical concepts and then present several typical practical real- izations and applications in the microwave regime. 相似文献
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采用劈裂-伪谱方法求解激光场中的含时薛定谔方程,探讨飞秒激光脉冲中氢原子波包的演化过程.研究了氢原子激发态的径向分布,角向分布、各态布居和电子云密度随时间的变化关系.在用共振激光脉冲控制氢原子波包演化的过程中径向分布、角向分布、各态布居和电子云密度随时间发生变化,但发现径向分布和角向分布在变化的过程中始终经过一些特殊点,并从理论上分析了存在这些特殊点的原因. 相似文献