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 χ 10<sup>-16</sup> 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 χ 10<sup>-17</sup> 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.
© 2002 Optical Society of America
Scott A. Diddams, L. Hollberg, Long-Sheng Ma, and Lennart Robertsson, "Femtosecond-laser-based optical clockwork with instability≤ less than or equal to 6.3 X 10-16 in 1 s," Opt. Lett. 27, 58-60 (2002)