Fiber based one-way time transfer with enhanced accuracy

To meet the request for access to accurate and reliable time, several time and frequency transfer methods using optical fibers have been developed or are under development. These fiber based techniques will overcome the issues of vulnerability in radio- and satellite solutions; however, they all rely on two-way transmission when variations in transfer time must be compensated for. As an alternative, a one-way transmission over fiber optic WDM-network has been proposed, with estimation of variation in transfer time based on detection of transfer time difference between two co-propagating lightwaves at different wavelengths. The technique was presented previously when the two wavelengths were far apart. Here we present results from an experiment where both wavelengths are within the optical C-band, i.e. within the gain bandwidth of Erbium-doped fiber amplifiers. Thereby it is proven that the technique is usable to a larger extent than previously demonstrated.