All fiber-coupled, long-term stable timing distribution for free-electron lasers with few-femtosecond jitter

Abstract

We report recent progress made in a complete fiber-optic, high-precision, long-term stable timing distribution system for synchronization of next generation X-ray free-electron lasers. Timing jitter characterization of the master laser shows less than 170-as RMS integrated jitter for frequencies above 10 kHz, limited by the detection noise floor. Timing stabilization of a 3.5-km polarization-maintaining fiber link is successfully achieved with an RMS drift of 3.3 fs over 200 h of operation using all fiber-coupled elements. This all fiber-optic implementation will greatly reduce the complexity of optical alignment in timing distribution systems and improve the overall mechanical and timing stability of the system.

Jitter analysis of timing-distribution and remote-laser synchronization systems

“…(5) indicates, there are three contributors to the output jitter of the TC-BOC: the freerunning jitters of the master and the slave laser, and the electronic noise jitter of the system. Since the master laser exhibits fairly low noise (< 0.17 fs RMS above 10 kHz [28]) and the measurement is shot-noise limited (i.e., J N is insignificant), the dominant noise factor at the output of the TC-BOC stems from the slave laser's inherent jitter, which is transferred to the TC-BOC output by |1/(1 + H)| 2 . Figures 4(a) and 4(b) show the calculated coefficients |1/(1 + H)| 2 and |H/(1 + H)| 2 using the transfer functions of the setup elements and the experimental parameters summarized in Appendix 2.…”

“…The master laser is a commercially available mode-locked laser (Origami-15 from Onefive GmbH) operating at 1554-nm center wavelength and 216.667-MHz repetition rate. In our earlier work [28], we have measured its free-running timing jitter, which is less than 0.4 fs RMS above 1 kHz and less than 0.17 fs RMS above 10-kHz offset frequency. The slave laser, on the other hand, is a home-built titanium-sapphire (Ti:sa) Kerr-lens modelocked laser operating at 800-nm center wavelength and 1.0833-GHz repetition rate.…”

Ultra-precise timing and synchronization for large-scale scientific instruments

“…a data acquisition card is usually used to sample the timing error, and control commands can be sent to a motorized delay line through a computer. Using fiber-coupled integrated BOC [38], fiber-coupled PBS, fiber-coupled Faraday mirror, and fiber-coupled motorized delay line, an all-fiber-coupled timing link stabilization system is demonstrated in [82]. The robustness and ease of implementation of these fiber-coupled devices can eliminate alignment-related problems observed in free-space optics.…”

“…It can be implemented using the techniques discussed in this paper. For example, timing link stabilization by [47,61,[81][82][83], the synchronization between the microwave reference and master laser, master laser to klystron, linear accelerators, and bunch compressor by [44][45][46][47][48][49][50][51][52]61,88,91,92], master laser to injector laser, seed laser and seed oscillator of the probe laser by [34,35,38,39,47,61,87,90], probe laser seed oscillator to probe laser output by [62][63][64][65][66], and x-ray timing characterization by [58][59][60][61].…”

Synchronous Mode-locked Laser Network with Sub-fs Jitter and Multi-km Distance

“…To realize the long standing scientific dream of capturing ultrafast structural dynamics with atomic resolution, new generation scientific facilities such as X-ray free-electron lasers [1] and intense laser beamline centers [2] aim to synchronize numerous mode-locked lasers with sub-fs precision across km-distances [3,4]. Similarly, comparison of remote optical clocks requires stabilized mode-locked lasers at each clock location to transfer the ultra-stable optical frequency to radio frequency (RF) domain as well as to the slave laser frequency responsible for the fiber-optic transmission [5].…”