调节X+2同位素分子电荷共振增强电离时刻获得高强度阿秒脉冲

Controlling charge resonance enhanced ionization of X+2 isotope molecules for generating high-intensity attosecond pulse

利用X+2同位素分子(H+2、D+2、T+2)谐波辐射的特点,提出一种有效获得高强度谐波连续区和孤立阿秒脉冲的方法.研究表明,在不同脉宽激光作用下,H+2、D+2和T+2分子可分别进入电荷共振增强电离区域.当激光振幅区域的半个周期正好处于电荷共振增强电离区域时,具有最大辐射能量的谐波能量峰正好具有最佳的辐射强度.随后,在此区域引入半周期单极激光场,被选择出来的谐波能量峰可以继续延伸,进而获得一个仅由单一能量峰贡献而产生的高强度谐波连续区.通过叠加连续区上的谐波可以获得脉宽仅为42 as的孤立阿秒脉冲.

Using the characteristics of harmonic generation from X+2 isotope molecules(H+2,D+2 and T+2),an effective method to generate a high-intensity spectral continuum and isolated attosecond pulse has been theoretically proposed.It is found that,driven by different pulse durations,H+2,D+2 and T+2 can enter into the charge resonance enhanced ionization region,respectively.When the half-cycle of the laser amplitude region is exactly in the charge resonance enhanced ionization region,the harmonic emission peak with the maximum emitted energy happens to have the optimal harmonic intensity.Further,by introducing a half-cycle unipolar pulse in this region,the selected harmonic emission peak can be extended,showing an intense spectral continuum contributed by single harmonic emission peak.Through superposing the harmonics on this spectral continuum,the pulse duration of 42 as isolated attosecond pulses can be obtained.