Optical frequency transfer via 146 km fiber link with 10 -19 relative accuracy.
We demonstrate the long-distance transmission of an ultrastable optical frequency derived directly from a state-of-the-art optical frequency standard. Using an active stabilization system we deliver the frequency via a 146-km-long underground fiber link with a fractional instability of 3 x 10(-15) at 1 s, which is close to the theoretical limit for our transfer experiment. After 30,000 s, the relative uncertainty for the transfer is at the level of 1 x 10(-19). Tests with a very short fiber show that noise in our stabilization system contributes fluctuations that are 2 orders of magnitude lower, namely, 3 x 10(-17) at 1 s, reaching 10(-20) after 4,000 s.
Grosche
G
G
Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig, Germany. gesine.grosche@ptb.de
Terra
O
O
Predehl
K
K
Holzwarth
R
R
Lipphardt
B
B
Vogt
F
F
Sterr
U
U
Schnatz
H
H