非均匀组合场驱动He原子获得高强度keV阿秒脉冲

Generation of high-intensity keV attosecond pulse from He atom driven by inhomogeneous combined field

摘要:

理论提出了一种利用非均匀组合场驱动He原子产生高强度keV高次谐波光谱和阿秒脉冲的方法. 结果表明，适当叠加多周期双色中红外场与一束少周期近红外场时，谐波截止能量可以得到有效延伸，并且谐波光谱呈现由单一量子路径贡献而成的平台区. 随后，适当引入一束紫外光源，在共振增强电离的影响下，谐波辐射效率可以增强500倍. 最后，通过叠加平台区的谐波，可获得多个脉宽持续范围在35 as以下的单个阿秒脉冲.

Abstract:

A potential method to produce the high-intensity keV high-order harmonic generation spectrum and the attosecond pulse has been proposed by using the inhomogeneous combined field. The results showed that with the proper superposition of two-color multi-cycle mid-infrared field and a few-cycle near-infrared field, the harmonic cutoff can be extended and a harmonic plateau contributed by the single quantum path can be obtained. Thereafter, by properly adding an ultraviolet pulse, the signal of the harmonic plateau can be enhanced by 500 dB due to the resonance ionization. Finally, by superposing some selected harmonics, some attosecond pulses shorter than 35 as can be obtained.