时-空域波形优化延伸高次谐波截止能量的研究

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．

Study on time-space waveform optimization for extension of high-order harmonic cutoff energy

Based on the three-step model of high-order harmonic generation, the effect of time-space waveform control on the extension of the harmonic cutoff energy has been theoretically studied. In the case of time region waveform control, by properly changing the laser intensity ratio, the laser phase and the time delay, the optimal three-color laser waveform can be obtained. Driven by this laser waveform, the harmonic cutoff can be extended. In the case of space region waveform control, based on the above best waveform as well as by choosing the appropriate positive laser inhomogeneous effect, the harmonic cutoff energy can be further extended. Moreover, with the increase of the inhomogeneous parameter, the harmonic cutoff can be extended. By analyzing the laser waveform, the spatial inhomogeneous effect and the harmonic emission process, the reason for the extension of the harmonic cutoff energy can be found. Furthermore, by properly superposing some harmonics, a single attosecond pulse with a duration of 45 as can be obtained.