CAJ | 학술논문

由中红外激光场（波长为2128nm）驱动He原子，在极化门的控制下，通过强场近似方法（ SFA）研究了He原子发射高次谐波的特点.研究表明，在这种组合场驱动下He原子可产生截止位置很高的高次谐波，并且在接近截止位置的平台区展现了超连续的特点，对该超连续部分的高次谐波进行叠加，可得到宽度为44.5as的单个超短脉冲．为了了解该超短阿秒脉冲的产生机理，我们对高次谐波谱的发射过程进行了时频分析，分析表明由于极化门的存在，有效地抑制了极化门以外的阿秒脉冲的发射，从而获得单个阿秒脉冲．
유중홍외격광장（파장위2128nm）구동He원자，재겁화문적공제하，통과강장근사방법（ SFA）연구료He원자발사고차해파적특점.연구표명，재저충조합장구동하He원자가산생절지위치흔고적고차해파，병차재접근절지위치적평태구전현료초련속적특점，대해초련속부분적고차해파진행첩가，가득도관도위44.5as적단개초단맥충．위료료해해초단아초맥충적산생궤리，아문대고차해파보적발사과정진행료시빈분석，분석표명유우겁화문적존재，유효지억제료겁화문이외적아초맥충적발사，종이획득단개아초맥충．
We investgate the high-order harmonic generation( HHG) emission of helium atom exposed to the midinfrared fields(λ=2128nm) with polarization gating by the strong field approximation(SFA) method.It is shown that the cut-off of HHG from helium atom driven by the fields is extended, and the supercontinuum spec-tra on the platuea near the cut-off are obtained.As a result, an isolated 44.5as pulse is generated by superpo-sing the some range of the supercontinuum spectra.In order to explain the emission process of HHG, we also perform the time-frequency analysis.Our results indicate that the emission of attosecond pulses outside the ga-ting are suppressed when the polarization gating is used, thus a single isolated ultrashort pulse can be generated.