Analysis of the Sagnac effect on the accuracy of the long haul optical fiber time transfer system

The influence of Sagnac effect in time transferring system over optical fiber is explained. Mathematical expression of the time deviation is deducted between any two points on the surface of the earth based on the analyses of the actual propagation path of the optical signal. To investigate the magnitude of the time deviation, we make theoretical calculation using the deducted equation when time is transferred from Prague to other four Europe cities with different directions through spherical circumference fiber links. It is demonstrated that the magnitude may reach 10^-9s when the transfer distance is longer than hundreds of kilometers and it is also decided by practical route of the fiber links. So accurate time compensation or calibration should be committed for the purpose of reaching subnanosecond accuracy in long-haul optical fiber time transferring system.