Femtosecond-laser-based optical clockwork with instability ≤63 × 10^–16 in 1 s

This is the authors' abstract. We don't add key points for this paper.

Two octave-spanning optical-frequency combs (750-MHz comb spacing) are phase locked to a common continuous-wave laser diode. The measured instability of the heterodyne beat between the two combs demonstrates that the intrinsic fractional frequency noise of a comb is </=6.3 chi 10(-16) in 1 s of averaging across the ~300-THz bandwidth. Furthermore, the average frequencies of the elements of the two combs are found to agree within an uncertainty of 4 chi 10(-17) across the entire octave. We demonstrate the possibility of transfering the stability and accuracy of the best current optical standards to ~500,000 individual oscillators across the visible and near-infrared spectrum.