Synchronizing femtosecond laser with x-ray synchrotron operating at arbitrarily different frequencies
- Department of Physics, Soongsil University, Seoul 156-743 (Korea, Republic of)
- Korea Research Institute of Standards and Science, Daejeon 305-600 (Korea, Republic of)
- Pohang Accelerator Laboratory, Pohang 790-784 (Korea, Republic of)
- Department of Physics, DePaul University, Chicago, Illinois 60614 (United States)
The ability to synchronize a femtosecond laser to x-ray pulses is crucial for performing ultrafast time-resolved x-ray scattering experiments at synchrotrons. Conventionally, the task has been achieved by locking a harmonic frequency of the laser oscillator to the storage ring master radio-frequency (RF). However, when the frequency mismatch between the two sources cannot be compensated by small adjustments to the laser cavity length, synchronization to a harmonic frequency requires modifying the optical components of the laser system. We demonstrate a novel synchronization scheme, which is a flexible alternative for synchronizing these two sources operating at arbitrarily different frequencies. First, we find the greatest common divisor (GCD) of the two frequencies that is still within the limited tuning range of the laser cavity length. The GCD is generated by dividing down from the storage ring RF, and is separately multiplied up to provide a feedback signal for synchronizing the laser cavity. Unique to our scheme, the GCD also serves as a harmonic RF source for the laser amplifier such that only laser oscillator pulses at fixed integer multiples of the storage ring RF are selected for amplification and delivery to experiments. Our method is implemented at the Photon Test Facility beamline of Pohang Light Source where timing-jitter less than 4 ps (r.m.s.) is measured using a new shot-to-shot method.
- OSTI ID:
- 22392297
- Journal Information:
- Review of Scientific Instruments, Vol. 85, Issue 12; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
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