Coherent microwave transfer over a 204-km telecom fiber link by a cascaded system

We have demonstrated a microwave transfer over a 204-km noisy urban fiber link by a cascaded system with 2 stages, which connected 10-GHz and 1-GHz transfer systems in series. A diurnal phase-noise cancellation ratio of 45 dB was obtained by use of an electronic phase-noise compensation system. Additionally, the stabilities reached 6 × 10 ^-14 at 1 s and 5 × 10 ^-17 at one-half day, which agreed with the root-sumsquare of those of the 10-GHz and 1-GHz transfers. We verified for the first time that the transfer stability degrades only ¿(N) times in a cascaded system with N stages.