We report on an optical fibre frequency transfer technique that avoids traditional group-delay actuation bandwidth- and range-limitations to deliver world-leading optical- and microwave-frequency transfer performance.
We present an actuation technique for suppressing uncorrelated noise between two optical frequencies to obtain ultra-stable microwave frequency dissemination over optical fibre. This technique will enable dual optical and microwave frequency transfer between the University of Western Australia and Yarragadee Satellite Laser Ranging station, which has application for the Atomic Clock Ensemble in Space (ACES) mission and other precision navigation and timing technologies. We build on the technique presented in [1], which demonstrates microwave transfer stability of 10−14 at 1s integration time by stabilising the group delay of an two correlated optical signals. A second actuator has been developed to suppress the remaining uncorrelated phase fluctuations between two optical frequencies by implementing optical-wavelength-scale action to vary the microwave phase. The actuator has been designed with the aid of a simulation that predicts actuation bandwidth and loss for a range of actuator parameters.