Generation of attosecond pulses with a controllable carrier-envelope phase via high-order frequency mixing

Advancing table-top attosecond sources in brightness and pulse duration is of immense interest and importance for an expanding sphere of applications. Recent theoretical studies [New J. Phys. 22, 093030 (2020)] found that high-order frequency mixing (HFM) in a two-color laser field can be much more efficient than high-order harmonic generation (HHG). Here we study the attosecond properties of the coherent extreme ultraviolet (XUV) generated via HFM analytically and numerically, focusing on the practically important case when one of the fields has much lower frequency and much lower intensity than the other one. We derive simple analytical equations describing intensities and phase locking of the HFM spectral components. We show that the duration of attosecond pulses generated via HFM, while being very similar to that obtained via HHG in the plateau, is shortened for the cutoff region. Moreover, our study demonstrates that the carrier-envelope phase of the attopulses produced via HFM, in contrast to HHG, can be easily controlled by the phases of the generating fields.

Automated summary

This study investigates the attosecond properties of coherent extreme ultraviolet (XUV) generated via high-order frequency mixing (HFM) through theoretical and numerical analysis. The research finds that the duration and carrier-envelope phase of the attosecond pulses generated by HFM can be effectively controlled, especially when one of the generating fields has much lower frequency and intensity compared to the other.