利用多周期空间非均匀啁啾场产生单个短阿秒脉冲

提出了一种直接生成单个短阿秒脉冲的有效方案.采用数值求解一维含时薛定谔方程，理论研究了多周期空间非均匀啁啾场驱动预激发氦离子的高次谐波辐射和阿秒脉冲的产生.结果表明：在空间非均匀啁啾场作用下，谐波截止可扩展至1050阶次，并且高于300阶次以上的谐波是连续的.由于连续谱来自单一量子路径的贡献，滤出连续谱上880-1120阶次的谐波，直接产生了一个脉宽为11.4 as的单个脉冲.通过增加驱动脉冲的持续时间，可获得一个脉宽短至10 as的单个脉冲.

Isolated short attosecond pulse generation by a multicycle spatially inhomogeneous chirped field

An efficient scheme for producing an isolated short attosecond pulse is proposed. By numerically solving one-dimensional time-dependent Schrödinger equation, the high-order harmonics and attosecond pulse generation of a pre-excited helium ion driven by a multicycle spatially inhomogeneous chirped field are investigated theoretically. The results show that the harmonic cutoff is significantly extended to the 1050th order and the harmonics beyond the 300th order are continuous in the spatially inhomogeneous chirped field. Because the supercontinuum only derives from the contribution of the single quantum path and covers extremely a wide spectral width, an isolated 11.4 as pulse is directly generated by filtering out the harmonics of the 880th-1120th order in the supercontinuum. By increasing the duration time of the driving pulse, a single attosecond pulse as short as 10 as is obtained.