23–28 Aug 2026
America/Los_Angeles timezone

Recent progress in attosecond X-ray free-electron lasers: direct observation for hard X-rays, high repetition rates, and spectrotemporal shaping

FRY02
28 Aug 2026, 11:00
30m
Invited Oral Presentation Session 12: Advanced FEL Modes Advanced FEL Modes (Invited)

Speaker

River Robles (Stanford University)

Description

Attosecond science with XFELs is a rapidly growing field. Nearly half of soft X-ray LCLS user experiments now use attosecond pulses. In this talk, I will present recent advances in the generation and characterization of attosecond pulses at the LCLS and LCLS-II, focusing on three main topics:
1. First direct observation of attosecond pulses in the hard X-ray domain.
2. Attosecond lasing in a high repetition rate, CW superconducting accelerator.
3. Spectrotemporal shaping techniques for attosecond XFEL pulses.
On the first point, I will show results from two different experiments demonstrating 9 keV pulses with sub-400-as duration, with direct measurements enabled by recent advances in broadband hard X-ray optics. I will then show the first attosecond soft X-ray lasing results from the LCLS-II at 16 kHz with pulse duration measurements using angular streaking in a circular time of flight spectrometer array. Extending on that, I’ll present two different techniques for shaping the spectrotemporal structure of attosecond pulses, highlighting experimental evidence from the LCLS-II of coherent attosecond pulse pairs and trains with tunable color separations, time delays, and relative phases. Altogether, these results open the doors to (1) attosecond scattering experiments and electronic-damage-free measurements, (2) the full realization of attosecond pump attosecond probe spectroscopy, and (3) attosecond coherent control in the X-ray domain.

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Authors

Agostino Marinelli (SLAC National Accelerator Laboratory) Alberto Lutman (SLAC National Accelerator Laboratory) Aliaksei Halavanau (SLAC National Accelerator Laboratory) David Cesar (SLAC National Accelerator Laboratory) Diling Zhu (SLAC National Accelerator Laboratory) Emily Thierstein (Stanford University) Erik Isele (Stanford University) Gabriel Just (SLAC National Accelerator Laboratory) Giacomo Griseri (SLAC National Accelerator Laboratory) James Cryan (SLAC National Accelerator Laboratory) Jun Wang (SLAC National Accelerator Laboratory) Kirk Larsen (SLAC National Accelerator Laboratory) Kurtis Borne (SLAC National Accelerator Laboratory) Mat Britton (SLAC National Accelerator Laboratory) Ming-Fu Lin (SLAC National Accelerator Laboratory) Nick Sudar (SLAC National Accelerator Laboratory) Paris Franz (Stanford University) Randy Lemons (SLAC National Accelerator Laboratory) Razib Obaid (SLAC National Accelerator Laboratory) River Robles (Stanford University) Sanghoon Song (SLAC National Accelerator Laboratory) Sergio Carbajo (University of California, Los Angeles) Takahiro Sato (SLAC National Accelerator Laboratory) Taran Driver (SLAC National Accelerator Laboratory) Veronica Guo (Stanford University) Xiang Li (SLAC National Accelerator Laboratory) Yanwen Sun (SLAC National Accelerator Laboratory) Zhen Zhang (SLAC National Accelerator Laboratory)

Presentation materials

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