Time transfer within 100ps uncertainty through 10 Km long optical fibre link

Precise time and frequency signal transfer over a long distance is one of the key activity in time and frequency metrology as precise time plays critical roles in many of the advanced technology as well as in scientific research. Since, last few decades optical fibre-based time and frequency signal transfer techniques has attracted immense importance as optical fibre-based methods show very low instability over long distances in various configurations. This article presents the time synchronization of a remotely located clock with a reference atomic clock over a 10 km long optical fibre link within an uncertainty of 100 ps. Effect of ambient conditions mainly temperature variations on the White Rabbit (WR) based optical fibre link has been studied and a simple method to mitigate the effect of ambient variation on time synchronization accuracy has been presented. Stability of the phase compensated optical fibre link in terms of modified Allan deviation is reaching ~ 10 –16 within one day of integration time and time deviation goes down to 2.2ps at 256 sec integration time.