Synchronous multi-color laser network with daily sub-femtosecond timing drift

Abstract

Filming atoms in motion with sub-atomic spatiotemporal resolution is one of the distinguished scientific endeavors of our time. Newly emerging X-ray laser facilities are the most likely candidates to enable such a detailed gazing of atoms due to their angstrom-level radiation wavelength. To provide the necessary temporal resolution, numerous mode-locked lasers must be synchronized with ultra-high precision across kilometer-distances. Here, we demonstrate a metronome synchronizing a network of pulsed-lasers operating at different center wavelengths and different repetition rates over 4.7-km distance. The network achieves a record-low timing drift of 0.6 fs RMS measured with 2-Hz sampling over 40 h. Short-term stability measurements show an out-of-loop timing jitter of only 1.3 fs RMS integrated from 1 Hz to 1 MHz. To validate the network performance, we present a comprehensive noise analysis based on the feedback flow between the setup elements. Our analysis identifies nine uncorrelated noise sources, out of which the slave laser’s inherent jitter dominates with 1.26 fs RMS. This suggests that the timing precision of the network is not limited by the synchronization technique, and so could be much further improved by developing lasers with lower inherent noise.

Femtosecond optical two-way time-frequency transfer in the presence of motion

“…Here, we derive Equations ( 15)a-d. Equations (15)b and (15)d follow directly from the definitions, ( 13) and ( 14), combined with Eqns. ( 11) and ( 9), respectively.…”

“…Nevertheless, compared to mature, deployed fiber-based approaches [5][6][7][8][9][10][11][12][13][14][15], O-TWTFT is still at an early stage. Indeed, Refs.…”

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

“…Using the same 4.7-km timing link network in Fig. 14, a multicolor laser network with daily 0.6-fs timing drift is demonstrated using two-color BOCs [90]. A microwave network is also realized with a total residual phase error of 147 μrad at 10 GHz integrated from 0.1 mHz to 100 MHz [91,92].…”

“…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].…”

Open-loop polarization mode dispersion mitigation for fibre-optic time and frequency transfer

“…With high-power, high-speed photodetectors the performance can be carried over to the microwave regime [14][15][16][17] where very-long baseline interferometry, future telecommunications systems and time-resolved ultrafast x-ray studies can benefit from low-phase-noise sources and precise synchronization. Because of this a considerable amount of effort has been put into fiberoptic time [12,13,[18][19][20][21][22][23][24][25][26][27][28], optical frequency [29][30][31][32][33][34][35], and RF frequency [36][37][38][39][40][41][42][43][44][45][46][47] distribution technologies and combinations thereof.…”