共查询到20条相似文献,搜索用时 78 毫秒
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采用含时密度泛函方法,结合赝势模型和电子交换相关作用的广义梯度近似,模拟了氮分子在超强飞秒激光脉冲作用下的高次谐波产生现象,并研究了激光脉冲偏振方向对氮分子高次谐波的影响.结果表明氮分子的高次谐波谱具有典型原子谐波谱的特征;谐波谱强度随着θ(激光偏振方向与分子轴向夹角)的增大而减小.这与J.Itatanl在Nature上报道的实验结果基本一致.
关键词:
含时密度泛函理论
激光偏振方向
高次谐波
氮分子 相似文献
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本文研究了一维初态为基态与第一激发态等权线性迭加态的模型原子在不同正啁啾激光脉冲辐照下的高次谐波发射谱。数值结果表明,谐波谱平台的截止位置随啁啾系数的增大大幅度的展宽。采用SMT(simple man’s theory)仔细分析了各啁啾激光场辐照下电子的动力学行为,阐明了谐波谱平台随啁啾系数增大而展宽的机制。 相似文献
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采用二维渐近边界条件和辛算法数值求解激光与多势阱系统相互作用的二维含时Schr(o|¨)dinge方程的无穷空间初值问题.计算二维多势阱系统分别在线偏振激光和圆偏振激光作用下的谐波发射,得到不同模型发射谐波谱的特点,说明多势阱环境有利于高次谐波的发射. 相似文献
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BEPCII是一个多束团、大流强的装置, 由于高频腔的高次模和电阻壁阻抗等因素,不可避免地会出现束流不稳定性。BEPCII中采用束流反馈系统来抑制束流不稳定性。横向束流反馈系统主要包括前端电子学、信号处理电子学、反馈器件和放大器等几个部分。梳状滤波器是信号处理电子学的重要部件,利用两根长短不同的电缆以及一个功分器和合成器构成了一种简单有效的梳状滤波器,其梳状深度达到-41 dB,使用这种梳状滤波器的横向反馈系统成功地抑制了束流中出现的不稳定性。 相似文献
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A laser model is formulated in terms of quantum harmonic oscillators. Emitters in the low lasing states are usual harmonic oscillators, and emitters in the upper states are inverted harmonic oscillators. Diffusion coefficients, consistent with the model and necessary for solving quantum nonlinear laser equations analytically, are found. Photon number fluctuations of the lasing mode and fluctuations of the population of the lasing states are calculated. Collective Rabi splitting peaks are predicted in the intensity fluctuation spectra of the superradiant lasers. Population fluctuation mechanisms in superradiant lasers and lasers without superradiance are discussed and compared with each other. 相似文献
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LI Xuexin LIU Yaqing ZHAI KanXU Zhizhan HAN Shensheng 《Chinese Journal of Lasers》1997,6(6):539-542
EfectsofPulseDurationsonHighorderHarmonicGenerationLIXuexinLIUYaqingZHAIKanXUZhizhanHANShensheng(ShanghaiInstituteofOpticsan... 相似文献
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数值研究了双色激光脉冲与一维氩原子相互作用的谐波发射功率谱.双色激光脉冲由800 nm和1600 nm的两束激光组成,脉冲持续时间为9.7 fs.计算结果表明,相对相位为π时,谐波截止频率从单色场情形的58 eV大幅度地展宽到316 eV,获得频宽为93 eV的软X射线连续辐射谱.此外,还采用短程的普薛耳-特勒势和长程的软化库仑势进行比对,数值结果表明该连续辐射谱的存在具有普适性.通过半经典的“三步”模型和时频分析小波变换方法对该连续辐射谱进行分析,发现其主要由单一的“短”量子路径生成,直接叠加频率从22
关键词:
红外双色激光脉冲
连续辐射谱
阿秒脉冲 相似文献
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The high-order harmonic generation using ellipticity-modulated laser field is investigated experimentally and theoretically. The laser field with time-varying ellipticity is obtained using two quarter wave plates. The harmonic spectral intensity peaks appear periodic for the localization induced by the ellipticity modulation of the laser pulse. We calculate the single-atom response to the driving laser field using the Lewenstein model and compare the calculated and measured harmonic spectra generated with ellipticity-modulated driving laser pulses. The theoretical simulation and the experiment results agree well with each other. 相似文献
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在高次谐波发射三步模型的指导下,理论研究了三色场时-空域波形调控对谐波截止能量的影响.在时域调控下,通过改变三束激光场的强度比、相位和延迟时间获得了最佳的三色场时域波形.在该波形下,谐波截止能量得到最佳延伸.在空间调控下,在上述最佳波形的基础上选择适当的正向激光非均匀效应后,谐波截止能量得到了进一步延伸.并且,随着非均匀参数增大,谐波截止能量也可持续增大.通过分析激光波形、空间非均匀效应和谐波发射过程给出了谐波截止能量延伸的原因.并且,通过叠加部分谐波可获得脉宽为45as的单个脉冲. 相似文献
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Decoding the electron dynamics in high-order harmonic generation from asymmetric molecular ions in elliptically polarized laser fields 下载免费PDF全文
Cai-Ping Zhang 《中国物理 B》2022,31(4):43301-043301
The high-order harmonic generation from an asymmetric molecular ion is theoretically investigated based on the Born-Oppenheimer model with two-dimensional electron dynamics. It is shown that the harmonic intensity changes periodically in elliptically polarized laser fields. The periodical character is ellipticity-dependent. By establishing the physical image, the periodicity of the harmonic intensity can be ascribed to the contributions of the ground state and the excited state. Furthermore, the electron dynamics from different electronic states can be selected via combining the elliptically polarized laser field with a static electric field. The harmonics dominated either by ground state or excited state are emitted once in an optical cycle in the combined laser field. 相似文献