Tunable spectral continuous shift of high-order harmonic generation in atoms by a plasmon-assisted shaping pulse

We delve into the phenomenon of high-order harmonic generation within a helium atom under the influence of a plasmon-assisted shaping pulse. Our findings reveal an intriguing manipulation of the frequency peak position in the harmonic emission by adjusting the absolute phase parameter within the frequency domain of the shaping pulse. This phenomenon holds potential significance for experimental setups necessitating precisely tuned single harmonics. Notably, we observe a modulated shift in the cr...     

Tunable spectral shift of high-order harmonic generation in atoms using a sinusoidally phase-modulated pulse

High-order harmonic generation (HHG) from an atom illuminated by a sinusoidally phase-modulated pulse is investigated by solving the time-dependent Schrödinger equation. The spectral shift that occurs in atomic HHG can be achieved easily using our laser pulse. It is shown that the photon energy of the generated harmonics is controllable within the range of 1 eV. The shift of the frequency peak position is rooted in the asymmetry of the rising and falling parts of the laser pulse. We also show that by varying the phase parameters in the frequency domain of the laser one can adjust and control the shift in atomic harmonic spectra.     

强场一维模型问题的保Wronskian守恒算法

提出辛算法是保Wronskian守恒的算法,把辛算法应用于强激光场一维模型的计算中,结果显示,Wronskian保持不变,与理论分析一致。     

Simultaneous study of the lower order harmonic and photoelectron emission from an atom in intense laser pulse

We simultaneously investigate variations of a low order harmonic and photoelectron emission with an incident laser intensity by solving the time-dependent Schr o¨dinger equation in a momentum space. It can be found that, the intensity of low order harmonic and photoelectron are gradually enhanced with the increase of the laser intensity, when the laser frequency is not in resonance with the transition frequency between the laser-induced high excited states and the ground state. If the resonance occurs, the intensity of the lower order harmonic is reduced and the interference can be observed in the lower order photoelectron spectra.     

一维模型原子在组合脉冲辐照下的高次谐波发射

本文采用SMT（sknple man’s theory）仔细分析了一维普薛耳-特勒势（P—T势）模型原子在高、低频组合强激光脉冲辐照下电子的动力学行为。并且，在此基础上，着力讨论了电离电子在激光脉冲策动下回核并与之复合从而发射高次谐波的平台结构，采用一种特殊设计的高、低频脉冲组合方案。使谐波发射效率较之于只用单一低频激光时的谐波发射效率提高两个数量级。     

采用较长脉宽双色场获得孤立阿秒脉冲（第15届全国原子与分子物理会议）

通过数值求解一维含时薛定谔方程,本文研究了具有较长脉宽双色激光脉冲与氢原子模型相互作用产生的谐波辐射谱。研究发现,当采用12个光学周期的特定组合脉冲时,孤立阿秒脉冲可以实现。这里特定组合脉冲由两束类似频率脉冲( )构成,附加脉冲的作用恰是调整基频光电场的形状。不同于入射基频光,整形后的基频光在时间始末端电场振幅被抑制,只有中间部分电场对谐波谱有贡献,它的作用等同于单一6飞秒超短脉冲的效果。从而扩展获得孤立阿秒脉冲所需脉宽从6飞秒到12飞秒。     

一维模型原子在组合脉冲辐照下的高次谐波发射

本文采用SMT (simple man's theory) 仔细分析了一维普薛耳-特勒势(P-T势)模型原子在高、低频组合强激光脉冲辐照下电子的动力学行为.并且, 在此基础上,着力讨论了电离电子在激光脉冲策动下回核并与之复合从而发射高次谐波的平台结构.采用一种特殊设计的高、低频脉冲组合方案,使谐波发射效率较之于只用单一低频激光时的谐波发射效率提高两个数量级.     

采用适宜靶原子提高高次谐波的转化效率

通过对影响谐波转化效率因素的分析,提出选择适宜的靶原子对象,即选择在高能区具有较强连续态-基态耦合强度的靶原子,可以优化高次谐波的发射条件.本文的数值实验结果表明,利用该方案,可以把平台区尾部谐波的转化效率提高两个数量级.     

Ultrahigh Harmonic Generation from an Atom with Superposition of Ground State and Highly Excited States

We investigate the high-order harmonic generation from an atom prepared in a superposition of ground state and highly excited state. When the atom is irradiated by an ultrashort pulse, the cutoff position of the plateau in the harmonic spectrum is largely extended compared with the case that the atom is initially in the ground state. The physics of the extension of the high-order harmonic plateau can be interpreted by the spatial structure of the atomic initial wave packet. We can optimize the generation of high-order harmonics by substituting the excited state for a particular coherent superposition of some highly excited states to form a spatially localized excited wave packet.     

Influence of multi-photon excitation on the atomic above-threshold ionization

Using the time-dependent pseudo-spectral scheme, we solve the time-dependent Schr ¨odinger equation of a hydrogenlike atom in a strong laser field in momentum space. The intensity-resolved photoelectron energy spectrum in abovethreshold ionization is obtained and further analyzed. We find that with the increase of the laser intensity, the abovethreshold ionization emission spectrum exhibits periodic resonance structure. By analyzing the population of atomic bound states, we find that it is the multi-photon excitation of bound state that leads to the occurrence of this phenomenon, which is in fairly good agreement with the experimental results.