8. Optical clock distribution

The transfer of ultra-stable frequency signals between distant laboratories would benefit a wide range of applications such as time and frequency metrology, particle accelerators, and astrophysics. One such application is long baseline interferometry for radio astronomy. Low-jitter transfer of a frequency reference could be used to distribute a signal from a master oscillator to each telescope in an array of 60 radio telescopes over a distance of ~20 km.This would enable all telescopes in the array to phase-coherently collect data, thereby simulating a single telescope with a very large aperture. 

Stable radio and microwave frequency transmission over an optical link has already been demonstrated in many different. Frequency transfer using the optical phase of an ultra-stable laser over a dedicated fibre link was reported for distances up to about 200 km by several groups. The current challenge is to extend the frequency dissemination techniques over longer distances utilizing the installed fibre network. The extension is extremely challenging because the frequency dissemination system requires bidirectional links which play the roles of ultra long phase locked loops reassuring the stabilization of the phase along the transmission link.

Our group was very recently engaged with this activity and seeks to exploit its expertise in optical signal processing so as to provide high stability frequency dissemination links. Our primary aim is to elaborate ideas on the development of uni-directional ultra stable dissemination schemes, since bi-directionality over the same fiber is not preferred in installed optical networks.


Related projects

  • ESA 1-6648/10/NL/CBi