Performance of the 1880 km Long, Brillouin Amplification Based Fibre Link PTB-MPQ–PTB

We have extended the existing interferometric fibre link PTB-Strasbourg with a branch connecting the node at Karlsruhe Institute of Technology (KIT) to the Max Planck Institute of Quantum Optics (MPQ) in Garching/Munich. This fibre connection enables chronometric levelling experiments between PTB and MPQ, separated by a line-of-sight distance of about 460 km. Here, we study the performance of the PTB-MPQ fibre link which mainly employs stimulated Brillouin scattering as means of amplification. We consider two configurations: a single-span loop configuration and an antiparallel configuration with frequency transfer over the two concatenated, individually stabilized forward and backward links.