利用蝴蝶型纳米结构下的极化门方案输出单个阿秒脉冲
Generation of single attosecond pulse by using polarization gating scheme in bowtie-shaped nanostructure

理论研究了在蝴蝶型纳米结构下运用多周期极化门方案驱动He原子输出高次谐波以及阿秒脉冲的特点。结果表明，由于纳米结构表面的等离子共振增强现象，谐波截止能量得到延伸。同时，由于激光场呈现空间非均匀性，长量子路径对谐波的贡献被减弱。并且，在极化门控制下，谐波平台区的贡献只来源于单一的谐波辐射能量峰，进而形成一个147 eV的超长平台区。最后，通过叠加平台区的谐波，可获得一个持续时间在30 as的超短脉冲。
The generations of the high-order harmonics and the attosecond pulses from helium atom driven by the multi-cycle polarization gating scheme in the bowtie-shaped nanostructure have been theoretically investigated. The results show that due to the surface plasmon polaritons, the extension of the harmonic cutoff can be achieved. Also, due to the spatial inhomogeneous effect of the laser field, the contribution of the harmonics from the long quantum path is reduced. Moreover, in the presence of the polarization gating scheme, the contribution of the supercontinuum is only from the single harmonic emission peak, thus resulting in a supercontinuum with the bandwidth of 147 eV. Finally, by properly superposing this supercontinuum, a single attosecond pulse with the full width at half maximum of 30 as can be obtained.