Coherent transfer of an optical carrier over 251 km.
We transfer an optical frequency over 251 km of optical fiber with a residual instability of 6x10(-19) at 100 s. This instability and the associated timing jitter are limited fundamentally by the noise on the optical fiber and the link length. We give a simple expression for calculating the achievable instability and jitter over a fiber link. Transfer of optical stability over this long distance requires a highly coherent optical source, provided here by a cw fiber laser locked to a high finesse optical cavity. A sufficient optical carrier signal is delivered to the remote fiber end by incorporating two-way, in-line erbium-doped fiber amplifiers to balance the 62 dB link loss.
Newbury
N R
NR
National Institute of Standards and Technology, Boulder, CO 80305, USA. nnewbury@boulder.nist.gov
Williams
P A
PA
Swann
W C
WC