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Femtosecond all-optical synchronization of an X-ray free-electron laser.

Schulz S, Grguraš I, Behrens C, Bromberger H, Costello JT, Czwalinna MK, Felber M, Hoffmann MC, Ilchen M, Liu HY, Mazza T, Meyer M, Pfeiffer S, Prędki P, Schefer S, Schmidt C, Wegner U, Schlarb H, Cavalieri AL - Nat Commun (2015)

Bottom Line: To generate these pulses and to apply them in time-resolved experiments, synchronization techniques that can simultaneously lock all independent components, including all accelerator modules and all external optical lasers, to better than the delivered free-electron laser pulse duration, are needed.Here we achieve all-optical synchronization at the soft X-ray free-electron laser FLASH and demonstrate facility-wide timing to better than 30 fs r.m.s. for 90 fs X-ray photon pulses.Crucially, our analysis indicates that the performance of this optical synchronization is limited primarily by the free-electron laser pulse duration, and should naturally scale to the sub-10 femtosecond level with shorter X-ray pulses.

View Article: PubMed Central - PubMed

Affiliation: Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.

ABSTRACT
Many advanced applications of X-ray free-electron lasers require pulse durations and time resolutions of only a few femtoseconds. To generate these pulses and to apply them in time-resolved experiments, synchronization techniques that can simultaneously lock all independent components, including all accelerator modules and all external optical lasers, to better than the delivered free-electron laser pulse duration, are needed. Here we achieve all-optical synchronization at the soft X-ray free-electron laser FLASH and demonstrate facility-wide timing to better than 30 fs r.m.s. for 90 fs X-ray photon pulses. Crucially, our analysis indicates that the performance of this optical synchronization is limited primarily by the free-electron laser pulse duration, and should naturally scale to the sub-10 femtosecond level with shorter X-ray pulses.

No MeSH data available.


Streaking map.The centre-of-mass (COM) of the Ne 2p photoelectron peak is shifted in kinetic energy depending on the temporal overlap of the ionizing FEL pulse and the streaking THz pulse. As the sources are closely synchronized, the shift in kinetic energy as a function of temporal overlap can be accurately mapped by averaging the shift over several single-shot measurements as the relative delay is scanned. Interpolating the averaged, shifted COM at each delay results in a continuous curve that can be used to map the exact arrival time of any streaked photoelectron spectrum generated by an FEL pulse that arrives within the ~720-fs, single-valued streaking ramp (indicated by the shaded region in the plot).
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f10: Streaking map.The centre-of-mass (COM) of the Ne 2p photoelectron peak is shifted in kinetic energy depending on the temporal overlap of the ionizing FEL pulse and the streaking THz pulse. As the sources are closely synchronized, the shift in kinetic energy as a function of temporal overlap can be accurately mapped by averaging the shift over several single-shot measurements as the relative delay is scanned. Interpolating the averaged, shifted COM at each delay results in a continuous curve that can be used to map the exact arrival time of any streaked photoelectron spectrum generated by an FEL pulse that arrives within the ~720-fs, single-valued streaking ramp (indicated by the shaded region in the plot).

Mentions: To retrieve the map directly from the set of streaking measurements, the centre-of-mass of each streaked single-shot spectrum was calculated and plotted versus the set delay where the measurement was recorded. The full set of measurements is composed of ~5,000 single shots collected over 3 ps of relative delay. The acquired data was then binned in time and interpolated to generate the transformation map plotted in Fig. 10. The furthest upshifted and downshifted single-shot photoelectron spectra were found at 225 and 190 eV, respectively, corresponding to a THz pulse with a peak electric field of 85 kV cm−1.


Femtosecond all-optical synchronization of an X-ray free-electron laser.

Schulz S, Grguraš I, Behrens C, Bromberger H, Costello JT, Czwalinna MK, Felber M, Hoffmann MC, Ilchen M, Liu HY, Mazza T, Meyer M, Pfeiffer S, Prędki P, Schefer S, Schmidt C, Wegner U, Schlarb H, Cavalieri AL - Nat Commun (2015)

Streaking map.The centre-of-mass (COM) of the Ne 2p photoelectron peak is shifted in kinetic energy depending on the temporal overlap of the ionizing FEL pulse and the streaking THz pulse. As the sources are closely synchronized, the shift in kinetic energy as a function of temporal overlap can be accurately mapped by averaging the shift over several single-shot measurements as the relative delay is scanned. Interpolating the averaged, shifted COM at each delay results in a continuous curve that can be used to map the exact arrival time of any streaked photoelectron spectrum generated by an FEL pulse that arrives within the ~720-fs, single-valued streaking ramp (indicated by the shaded region in the plot).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4309427&req=5

f10: Streaking map.The centre-of-mass (COM) of the Ne 2p photoelectron peak is shifted in kinetic energy depending on the temporal overlap of the ionizing FEL pulse and the streaking THz pulse. As the sources are closely synchronized, the shift in kinetic energy as a function of temporal overlap can be accurately mapped by averaging the shift over several single-shot measurements as the relative delay is scanned. Interpolating the averaged, shifted COM at each delay results in a continuous curve that can be used to map the exact arrival time of any streaked photoelectron spectrum generated by an FEL pulse that arrives within the ~720-fs, single-valued streaking ramp (indicated by the shaded region in the plot).
Mentions: To retrieve the map directly from the set of streaking measurements, the centre-of-mass of each streaked single-shot spectrum was calculated and plotted versus the set delay where the measurement was recorded. The full set of measurements is composed of ~5,000 single shots collected over 3 ps of relative delay. The acquired data was then binned in time and interpolated to generate the transformation map plotted in Fig. 10. The furthest upshifted and downshifted single-shot photoelectron spectra were found at 225 and 190 eV, respectively, corresponding to a THz pulse with a peak electric field of 85 kV cm−1.

Bottom Line: To generate these pulses and to apply them in time-resolved experiments, synchronization techniques that can simultaneously lock all independent components, including all accelerator modules and all external optical lasers, to better than the delivered free-electron laser pulse duration, are needed.Here we achieve all-optical synchronization at the soft X-ray free-electron laser FLASH and demonstrate facility-wide timing to better than 30 fs r.m.s. for 90 fs X-ray photon pulses.Crucially, our analysis indicates that the performance of this optical synchronization is limited primarily by the free-electron laser pulse duration, and should naturally scale to the sub-10 femtosecond level with shorter X-ray pulses.

View Article: PubMed Central - PubMed

Affiliation: Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.

ABSTRACT
Many advanced applications of X-ray free-electron lasers require pulse durations and time resolutions of only a few femtoseconds. To generate these pulses and to apply them in time-resolved experiments, synchronization techniques that can simultaneously lock all independent components, including all accelerator modules and all external optical lasers, to better than the delivered free-electron laser pulse duration, are needed. Here we achieve all-optical synchronization at the soft X-ray free-electron laser FLASH and demonstrate facility-wide timing to better than 30 fs r.m.s. for 90 fs X-ray photon pulses. Crucially, our analysis indicates that the performance of this optical synchronization is limited primarily by the free-electron laser pulse duration, and should naturally scale to the sub-10 femtosecond level with shorter X-ray pulses.

No MeSH data available.