29 / 2023-04-03 09:44:10

Attosecond pulses based on the high-order harmonics generated from laser-plasma interaction

极端光下的基础物理学 > 辐射源

Attosecond pulse is an essential tool for investigating various ultrafast dynamics with unprecedented spatial-temporal resolution. The high-order harmonics generated (HHG) by the interaction between an intense laser and plasma target provide a compact method of generating attosecond pulses. However, how to realize high energy output, high ellipticity, and isolation of attosecond pulses are key scientific problems related to its broad application. To solve these problems, we propose new types of targets such as capacitor targets, nano-foil targets, and double nano-foil targets, which not only improve the HHG efficiency by orders of magnitude, but also provide the possibility for the generation of isolated attosecond pulses. To generate circularly polarized (CP) attosecond pulses, driving pulses superposed by two-color co-rotated CP beams is adopted. When the frequencies of the two beams satisfy the frequency-doubling relationship, the superposition field can drive the target surface to oscillate rapidly at PHz frequency, and CP harmonics can be generated at normal incidence. When the frequencies of the two beams are similar, the beat field of two beams with different pulse widths can successfully excite the one-time HHG process, and the produced single attosecond pulse has higher ellipticities than that in the one-color laser cases. The above research is of great significance for expanding the application range of attosecond pulses.