Long-term timing stabilization for pump-probe experiments at SACLA.

Area of Science:

• Physics
• Laser Technology
• Experimental Methods

Background:

• Precise timing synchronization between X-ray free-electron lasers (XFELs) and optical lasers is crucial for pump-probe experiments.
• Long-term timing drift can significantly degrade experimental data quality and limit achievable resolution.

Purpose of the Study:

• To develop and implement a robust timing control system for stabilizing the temporal overlap between XFEL and optical laser pulses.
• To minimize timing jitter and drift in pump-probe experiments at the SPring-8 Ångstrom Compact free-electron LAser (SACLA).

Main Methods:

• Utilized an out-of-loop balanced optical-microwave phase detector for precise timing measurements.
• Implemented an arrival-timing monitor to track pulse arrival times.
• Employed a feedback control system to correct timing deviations.

Main Results:

• Achieved long-term timing stabilization with jitter and drift below 50 fs (RMS) over approximately 49 hours.
• Demonstrated high correlation in simultaneous timing monitoring across two experimental branches (BL3) with an RMS error of 8.6 fs over 8 hours.

Conclusions:

• The developed timing control system effectively stabilizes the relative timing between XFEL and optical laser pulses.
• The system's performance is suitable for demanding pump-probe experiments requiring high temporal precision.
• This stabilization technique enhances the reliability and accuracy of ultrafast measurements at XFEL facilities.