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少周期脉冲在稠密V型三能级介质中传播时的粒子布居演化 总被引:1,自引:1,他引:0
利用由预估计校正-时域有限差分(PC-FDTD)法求解Maxwell-Bloeh方程得到的数值解,研究少周期激光脉冲在稠密Ⅴ型三能级原子介质中传播时各能级粒子数布居的演化特性.结果表明,两跃迁偶极矩的比值(γ)对稠密介质中粒子数布居反转出现的时间和振荡的次数具有显著的影响,γ=1时,考虑洛仑兹局域场修正(LFC)时,粒子数反转出现的较晚,近偶极.偶极(NDD)相互作用延缓了粒子数的反转;γ1时,考虑LFC时,粒子数反转出现的较早,NDD相互作用加快了粒子数的反转;电偶极矩不同时,粒子数布居振荡的次数比相同时多.粒子数布居在稠密介质中的演化特性与稀疏介质中显著不同,在入界处,稀疏介质中粒子数布居可以实现长时间的反转;随着介质密度的增大,粒子数布居产生准周期性的振荡,但考虑LFC时,振荡的次数比不考虑LFC时少. 相似文献
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原子光激发过程中的选择性和相干性 总被引:1,自引:0,他引:1
通过求解含时Schrodinser方程,对于原子在激光场的共振和非共振驱动下向各个态的跃迁几率进行了计算和分析,探讨了跃迁几率的时间特性以及随激光参数的变化规律,揭示了光场与原子系统相互作用的相干性和选择性。计算并验证由解析解所预测的激发态粒子数布居的峰值和实现粒子数反转所应满足的条件。 相似文献
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四频差动激光陀螺中的粒子数脉动效应 总被引:1,自引:0,他引:1
为研究激光陀螺精细模耦合作用,考虑了增益介质中的粒子数脉动效应.从激光器物理原理出发,分析了粒子数脉动效应的产生机制,结合四频差动激光陀螺特点,得出粒子数脉动效应是一种精细模耦合效应,不同激光模式间的拍频使增益介质中粒子数布居差产生调制,进而对模耦合产生影响.数值计算了粒子数脉动在耦合效应中的大小.计算结果表明:粒子数脉动效应和其他耦合效应随腔频变化基本一致,在大多数腔频范围内数值较小,为其他耦合效应的4%以下;在某些腔频范围(如0.37<ξ<0.46,0.02<ξ<0.06,0.86<ξ<0.88)有较大数值,为其他耦合效应的80%以上,在激光陀螺的模耦合分析中不可忽略. 相似文献
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频率啁啾激光场中锂原子的激发与态囚禁 总被引:1,自引:1,他引:0
采用含时多态展开方法,对不同频率啁啾激光场中里德堡锂原子布居数的相干迁移特性进行了计算研究。结果表明:布居数跃迁几率对激光脉冲形状、激光场强度、啁啾率等参数非常敏感,在合适的激光参数下,可以实现布居数在四个量子态之间的完全迁移和量子态的囚禁。 相似文献
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采用波包动力学方法研究了HF分子基电子态的多光子跃迁. 激光场由两束频率比为1:2的重合红外脉冲构成. 态|0,0>作为初始态, 态|4,0>与态|4,2>分别作为目标态. 计算结果表明, 通过选取不同的共振频率, 可以控制布居跃迁至不同的目标态. 两束脉冲间的初相位差可以控制布居转移概率. 当初相位差为π/2的偶数倍时, 布居转移概率为最大值. 当初相位差为π/2的奇数倍时, 布居转移概率为最小值. 初相位差对于态|4,0>的布居影响大于态|4,2>.
关键词:
多光子跃迁
初相位
布居转移
波包 相似文献
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以脉冲染料激光器579 nm激光为激发源,采用双光子激光诱导色散荧光光谱方法,对SO2分子第一激发带A对称电子态的激发及复杂退激发过程进行了实验研究.基态SO2分子吸收两个579 nm光子被激发至A1A2态,通过能量内转换或碰撞弛豫实现在A1 A2,B1 B1与a3B1态多个振转能级的再布居.三个电子态基振动能级向基态X1A1不同振动能级跃迁形成了305和425 nm处荧光包络与以347nm为中心的规则序列.另外,还观测到了SO2分子的三光子激发过程X1A1 →C1B2,此激发产生了200~278nm处的荧光包络和425nm处的谱线叠加现象.由实验数据计算出了SO2分子有关电子态的对称振动和弯曲振动模式的基振动角频率及非谐性常数. 相似文献
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基于NO分子的双重态能级结构特性,利用分子光谱理论分析和计算了NO分子γ带系(A2Σ+→X2Πr)的发射光谱,并通过电晕放电实验光谱进行验证。理论上计算了NO高低能级的双重电子态的能级分布,同时利用r质心近似法求取了能级间跃迁的电偶极矩函数,并得到了不同振动、转动能级间的爱因斯坦跃迁概率,然后计算出不同振动温度和转动温度条件下谱线的强度分布。最后进行NO和N2混合气体的电晕放电实验,通过将实验发射光谱同理论计算结果进行对比分析,确定了NO分子的振动温度和转动温度。 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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Theoretical study of the influence of intense femtosecond laser field on the evolution of the wave packet and the population of NaRb molecule 下载免费PDF全文
Employing the two-state model and the time-dependent wave packet method, we have investigated the influences of the parameters of the intense femtosecond laser field on the evolution of the wave packet, as well as the population of ground and double-minimum electronic states of the NaRb molecule. For the different laser wavelengths, the evolution of the wave packet of 61Σ+ state with time and internuclear distance is different, and the different laser intensity brings different influences on the population of the electronic states of the NaRb molecule. One can control the evolutions of wave packet and the population in each state by varying the laser parameters appropriately, which will be a benefit for the light manipulation of atomic and molecular processes. 相似文献
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Influence of laser fields on the vibrational population of molecules and its wave-packet dynamical investigation 下载免费PDF全文
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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用含时波包法研究了三态阶跃型K_2分子在强飞秒泵浦-探测激光场中脉宽对波包动力学过程的影响.研究表明激光场强较弱或者脉宽较短都可能不出现Autler-Townes分裂.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.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.首次量化了脉宽对激发态布居数的影响,表明变化频率随着泵浦场强的增强而增大.研究表明调节激光脉宽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. 相似文献
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用含时波包法研究了三态阶跃型K2分子在强飞秒泵浦-探测激光场中脉宽对波包动力学过程的影响.研究表明激光场强较弱或者脉宽较短都可能不出现Autler-Townes分裂.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. 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.首次量化了脉宽对激发态布居数的影响,表明变化频率随着泵浦场强的增强而增大.研究表明调节激光脉宽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. 相似文献
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The influence of the ultra-short pulse wavelength on the populations in the three electronic states of CsI molecule is investigated using the time-dependent wave packet method. The calculated results show that the populations in the two excited states approach to the maxima at the wavelengths of 369 nm and 297 nm, respectively. The photodissociation reaction channels of the CsI molecule can be chosen by controlling the pump pulse wavelength. 相似文献
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M. Boca V. Florescu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(1):15-20
We define 1D Volkov states as solutions of the one-dimensional Dirac equation in a time dependent electric field, similar
to the Volkov solutions in the three dimensional case. They are eigenspinors of the momentum operator and reduce in the absence
of the field to free solutions of positive or negative energy. Then we add a time independent attractive Gausssian potential
and, by integrating the Dirac equation for a laser pulse of Gaussian shape,
we determine the state which coincides initially with the ground state of the system in the absence of the electric field.
Our main objective is the study of the population dynamics on the Volkov states during the pulse action. For different values
of the laser pulse intensity and two values of the potential depth, we find that the Volkov states which
evolve from free solutions of negative energy are practically not populated, in contrast to the
population on free negative energy states. 相似文献
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We present a theoretical study of dynamics of Rydberg states of lithium using ultra short chirped laser pulse having a Gaussian
envelope. The population transfer probabilities are calculated of different Rydberg states on chirped laser factors. The calculations
are performed by direct numerical integration of Schr?dinger equation using fourth order Runge-Kutta method. The behavior
of dynamics of Rydberg states for these factors is of great significance. These results are of potential interest in coherent
quantum control, quantum computation and in many physical and chemical processes. 相似文献