研究了空间非均匀啁啾场作用下氦离子的高次谐波辐射和单个阿秒脉冲的产生。计算结果表明:相比单个空间非均匀场和单个啁啾场驱动产生的谐波谱,空间非均匀啁啾场驱动产生的谐波谱的截止位置得到了极大的拓展,并且产生了带宽为1073 eV的超连续谱。此外,这种时空组合场可以实现抑制长路径而选取短路径,从而有效地贡献连续谱的产生。直接叠加连续谱上大范围的谐波,可获得脉宽为13 as的单个阿秒脉冲。通过调节啁啾参数,可实现脉宽仅为7.4 as的单个脉冲的输出。

In this study, we theoretically investigate the high-order harmonic and isolated attosecond pulse generation with respect to the helium ion in the spatially inhomogeneous chirped field. The results demonstrate that the harmonic spectral cutoff of the spatially inhomogeneous chirped field is significantly extended when compared with the harmonic spectra generated by the single inhomogeneous field and the chirped field. Subsequently, an ultrabroad supercontinuum with a bandwidth of 1073 eV is successfully obtained. Furthermore, the spatiotemporally synthesized field can suppress a long path and select a short path to efficiently contribute to supercontinuum generation. Therefore, an isolated 13 as pulse is directly generated by superposing a wide range of continuous harmonics. Finally, a single attosecond pulse with pulse width of 7.4 as can be easily obtained by adjusting the chirp parameter.