Transfer of optical frequency combs over optical fibre links

In just over a decade the optical frequency comb technique has completely transformed the field of frequency metrology. These devices have made the measurement of the frequency of light a much easier and affordable task when compared to with earlier techniques. With both research and technology development on these devices becoming more mature, optical frequency combs have been affecting other science areas. Applications are already found in spectroscopy, attosecond physics and astrophysics and more science and engineering areas can be expected to be affected in the near future.The dissemination over optical fibre of optical frequency combs between research labs, or between research labs and industry, could facilitate and accelerate this process. In particular, with optical frequency standards currently exhibiting a fractional accuracy better than 10-17 and optical frequency combs making this accuracy available across a wide spectrum, new experiments could be devised in a wide range of research fields if ultraaccurate microwave and optical frequencies were to be made available beyond the walls of metrology laboratories.However, before the work presented in this thesis, limited research was undertaken to test how accurately an optical frequency comb could be transferred over optical fibre. Environmentally-induced noise in the fibre, dispersion issues and other processes taking place during the propagation and detection of the optical signal could all degrade its quality to a level incompatible with the desired applications. The experiments described here demonstrate that optical frequency combs can be disseminated over optical links, from several-km to many tens of km-long, whilst preserving the stability and accuracy of its mode frequency spacing and mode frequency to a level compatible with the majority of the most demanding frequency metrology applications.