Bidirectional fibre is key for accurate optical frequency transfer

TiFOON partners AGH and PSNC have studied the performance of optical frequency transfer in duplex unidirectional DWDM networks. This approach to optical frequency transfer uses existing telecommunication infrastructure without the need for modifications to the installed fibre and equipment, making it very cost effective compared to dark fibre or dark channel.

The research, published in IEEE Transactions On Ultrasonics, Ferroelectrics, And Frequency Control, looks at the effect of DWDM components and the mismatch of individual fibres within a cable on stability. Using the Polish PIONIER DWDM network, the researchers show that an accuracy of few parts in 10¹⁶ can be achieved over 1500 km of fibre. This is comparable to the best satellite-based techniques but with significantly reduced averaging time. On other hand, several orders of magnitude better long-term stability and accuracy can be achieved with single bidirectional fibre.

The publication is freely available on the Zenodo TiFOON community hub.