Grupo de Investigación en Óptica Extrema, Universidad de Salamanca, E-37008 Salamanca, Spain.
Phys Rev Lett. 2013 Jul 19;111(3):033002. doi: 10.1103/PhysRevLett.111.033002. Epub 2013 Jul 18.
We demonstrate theoretically that the temporal structure of high harmonic x-ray pulses generated with midinfrared lasers differs substantially from those generated with near-infrared pulses, especially at high photon energies. In particular, we show that, although the total width of the x-ray bursts spans femtosecond time scales, the pulse exhibits a zeptosecond structure due to the interference of high harmonic emission from multiple reencounters of the electron wave packet with the ion. Properly filtered and without any compensation of the chirp, regular subattosecond keV waveforms can be produced.
我们从理论上证明，用中红外激光产生的高次谐波 X 射线脉冲与用近红外脉冲产生的脉冲在时间结构上有很大的不同，特别是在高光子能量下。具体来说，我们表明，尽管 X 射线爆发的总宽度跨越飞秒时间尺度，但由于电子波包与离子多次重遇产生的高次谐波发射的干涉，脉冲呈现出飞秒结构。适当滤波，不补偿啁啾，可以产生规则的亚阿秒 keV 波形。
