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

S Schulz,H Schlarb,P Prędki,M Ilchen,A L Cavalieri,M K Czwalinna,H Y Liu,M Felber,C Behrens,S Schefer,T Mazza,U Wegner,M C Hoffmann,H Bromberger,C Schmidt,S Pfeiffer,I Grguraš,M Meyer,J T Costello

doi:10.1038/ncomms6938

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.

Highlights

Many advanced applications of X-ray free-electron lasers require pulse durations and time resolutions of only a few femtoseconds
A general measure of the overall facility-wide synchronization is given by the timing stability that can be maintained between the FEL X-ray pulses and independent external optical laser pulses
We demonstrate overall synchronization of (28±2) fs r.m.s. or (66±5) fs full width at half maximum (FWHM) while delivering (90±18) fs FWHM FEL photon pulses

Summary

Introduction

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. 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. A general measure of the overall facility-wide synchronization is given by the timing stability that can be maintained between the FEL X-ray pulses and independent external optical laser pulses. The severe intensity fluctuations that were observed during the initial demonstration of the self-seeding technique[13] will be minimized, as the energy stability of the accelerator will be improved with better synchronization

Methods

Results

Conclusion