Visualization_Harmonics_video_s.mp4

For small time delays between the pulses similar to and smaller than the NIR pulse duration, interference between the two NIR pulse trains occurs, resulting in transient drops and peaks of the XUV output recurrent with a period that is corresponding to the laser’s fundamental wavelength. The video available as supplementary material shows this effect while the delay between the two pulses is scanned between + 67 fs to -20 fs. The HHG yield has been optimized before at a fixed delay of 870 fs. The 25th to the 53rd harmonics are shown (~ 30 eV - 64 eV, left side).