Spectrotemporal shaping of attosecond x-ray pulses with a fresh-slice free-electron laser

• Main Authors: Robles, River R, Larsen, Kirk A, Cesar, David, Driver, Taran, Duris, Joseph, Franz, Paris, Garratt, Douglas, Sudar, Nicholas, Wang, Jun, Zhang, Zhen, Cryan, James, Marinelli, Agostino
• Format: Journal Article
• Language: English
• Published: 04-03-2024
• Subjects: Physics - Accelerator Physics; Physics - Optics; Physics - Plasma Physics
• DOI: 10.48550/arxiv.2403.02189

We propose a scheme for coherently shaping attosecond x-ray pulses at
free-electron lasers. We show that by seeding an FEL with a short coherent seed
that overfills the amplification bandwidth, one can shape the wigner function
of the pulse by controlling the undulator taper profile. The examples of
controllable coherent pulse pairs and trains, as well as isolated
spectrotemporally shaped pulses with very broad coherent bandwidths are
examined in detail. Existing attosecond XFELs can achieve these experimental
conditions in a two-stage cascade, in which the coherent seed is generated by a
short current spike in an electron bunch and shaped in an unspoiled region
within the same bunch. We experimentally demonstrate the production of pulse
pairs using this method at the Linac Coherent Light Source.