High-sensitivity x-ray/optical cross-correlator for next generation free-electron lasers

Area of Science:

• Physics
• Optics
• Materials Science

Background:

• Ultrashort X-ray pulses are crucial for probing ultrafast phenomena.
• Accurate timing diagnostics are essential for high-resolution X-ray experiments.
• Current methods lack sufficient sensitivity in the soft X-ray regime.

Purpose of the Study:

• To design and realize a novel arrival time diagnostic for ultrashort X-ray pulses.
• To achieve unprecedented sensitivity in the soft X-ray regime.
• To enable sub-10 fs timing jitter at high-repetition-rate X-ray facilities.

Main Methods:

• Cross-correlation of soft X-ray pulses with a ≈1550 nm optical laser.
• Utilizing an interferometric detection scheme.
• Employing a multi-layer sample design to enhance measurement sensitivity.

Main Results:

• Achieved up to 275% relative signal change at 530 eV with 1.6 mJ/cm² soft X-ray exposure.
• Demonstrated a >100-fold improvement in sensitivity compared to previous techniques.
• Estimated arrival time measurement resolution of approximately 2.8 fs (rms).

Conclusions:

• The developed X-ray arrival time monitor offers superior sensitivity and resolution.
• This technology paves the way for advanced timing capabilities in X-ray science.
• Enables sub-10 fs timing jitter crucial for future X-ray free-electron lasers and synchrotrons.