Long-term stable, sub-femtosecond timing distribution via a 12-km polarization-maintaining fiber link: approaching 10^−21 link stability

Abstract

Long-term stable, sub-femtosecond timing distribution over a 1.2-km polarization-maintaining (PM) fiber-optic link using balanced optical cross-correlators for link stabilization is demonstrated. Novel dispersion-compensating PM fiber was developed to construct a dispersion-slope-compensated PM link, which eliminated slow timing drifts and jumps previously induced by polarization mode dispersion in standard single-mode fiber. Numerical simulations of nonlinear pulse propagation in the fiber link confirmed potential sub-100-as timing stability for pulse energies below 70 pJ. Link operation for 16 days showed ~0.6 fs RMS timing drift and during a 3-day interval only ~0.13 fs drift, which corresponds to a stability level of 10(-21).

All-Fiber Centralized Architecture for Parallel Terahertz Sensors

“…However, faster inspection systems, e.g. [24], would require active stabilization methods [23,[25][26], which can provide long term timing stability with up to subfemtosecond precision [26].…”

One-femtosecond, long-term stable remote laser synchronization over a 3.5-km fiber link

“…For the link stabilization [13], the optical pulse train (timing signal) generated from a mode-locked laser (master laser), is distributed between two remote locations through a dispersion-slope-compensated PM fiber link. Partial power of the link pulse is back-reflected by an output coupler at the end of the link.…”

“…Among many other fields, distributing stable timing signals is particularly important for modern large-scale scientific facilities, such as X-ray free-electron lasers (FELs) [9][10][11]. The operation of FELs depends on the tight synchronization of many microwave and optical devices [5,[12][13][14], including the electron gun, the photo-injector laser, the RF system in the linear accelerator, the seed laser, and so on. The European XFEL [10], the largest FEL under construction is 3.5 km long.…”

“…We have been advancing such a pulsed approach to timing distribution systems for the past decade [5,13,14]. To realize optical-to-optical synchronization [5,14], we made use of the balanced optical cross-correlation (BOC) locking method [5,15], because it can easily achieve tight locking with high locking bandwidth.…”

Passive phase correction for stable radio frequency transfer via optical fiber

“…To realize stable RF transfer, many schemes have been proposed, which can be generally classified into three categories. One method is to actively adjust the optical path by changing the length of the fiber link or the wavelength of the laser source [11][12][13][14][15][16][17][18][19][20][21][22]. The second approach is to pre-compensate the phase variation by introducing a conjugate phase to the RF signal before transmission via a phase shifter, a frequency shifter, or a voltage-controlled oscillator (VCO) [23][24][25][26][27][28][29][30][31][32][33][34][35].…”