High-resolution microwave frequency dissemination on an 86-km urban optical link

TL;DR

This paper demonstrates a highly stable 9.15 GHz microwave frequency transfer over an 86-km urban optical fiber link, achieving unprecedented stability levels suitable for advanced scientific and communication applications.

Contribution

It presents the first long-distance microwave frequency dissemination over an urban optical link with ultra-high stability, using novel phase noise compensation and dispersion management techniques.

Findings

Fractional frequency stability of 1.3x10^-15 at 1 s

Stability below 10^-18 after one day

Outperforms previous radiofrequency links

Abstract

We report the first demonstration of a long-distance ultra stable frequency dissemination in the microwave range. A 9.15 GHz signal is transferred through a 86-km urban optical link with a fractional frequency stability of 1.3x10-15 at 1 s integration time and below 10-18 at one day. The optical link phase noise compensation is performed with a round-trip method. To achieve such a result we implement light polarisation scrambling and dispersion compensation. This link outperforms all the previous radiofrequency links and compares well with recently demonstrated full optical links.