啁啾延迟调控在双原子分子谐波辐射中的作用

Effect of chirp-delay regulation on harmonic generation of diatomic molecules

为了获得高强度高次谐波光谱,提出了一种利用啁啾延迟来调控H2+和D2+谐波辐射强度的方法。结果表明:在短脉宽激光驱动下,H2+和D2+谐波辐射主要来自于激光下降区域。因此在激光下降区域引入啁啾小量会产生高强度谐波光谱连续区,并且H2+谐波辐射强度大于D2+谐波辐射强度。而在长脉宽激光驱动下,H2+和D2+谐波辐射的贡献分别来自激光上升和下降区域,因此分别在激光上升和下降区域引入啁啾小量会获得相应的高强度谐波光谱连续区,但H2+谐波辐射强度小于D2+谐波辐射强度。最后,选择适当的谐波平台区并通过叠加谐波可获得脉宽为36 as的孤立脉冲。

In order to obtain high order harmonic spectra with high-intensity,a method of chirp-delay regulation is proposed to control the harmonic intensity of H2+ and D2+.The results show that,when driven by shorter pulse duration,both of the harmonic spectra of H2+ and D2+ mainly come from the falling-region of laser field.Therefore,by properly introducing a chirp in the falling-region of laser field,the high-intensity spectral continuum can be obtained,and the harmonic intensity of H2+ is higher than that of D2+.However,when driven by longer pulse duration,the main contribution of harmonic spectra of H2+ and D2+ come from the rising and the falling region of laser field,respectively.Thus,the corresponding high-intensity spectral continuum can be produced by introducing the chirps in the rising or the falling region of laser field,and the harmonic intensity of H2+ is lower than that of D2+ in this case.Finally,by selecting the appropriate spectral continuum and superposing the harmonics,a single attosecond pulse with the pulse duration of 36 as can be obtained.