Effects of Link Delay Fluctuations on Stability of Fiber-Optic Time Transfer

Abstract

The delay fluctuations of optical fiber link, related to the variations of laser output wavelength and ambient temperature along the transmission link, directly affect the stability of fiber-optic time transfer. The relationship between the stability of long distance fiber-optic time transfer and the variations of laser wavelength and the temperature of optical fiber link is derived by using a link segmentation processing method. Wavelength fluctuations are modeled based on the analysis of measured wavelength data of laser. A 3000 km optical fiber link is emulated based on the actual temperature data, and the effects of wavelength fluctuations and depth of buried optical fiber link on the stability of fiber-optic time transfer adopting bidirectional time division multiplexing (BTDM) and wavelength division multiplexing (WDM) respectively are analyzed. The results show that the temperature variations of optical fiber link mainly have effect on the long-term stability, and this effect changes with the depth of buried optical fiber link and work season of time transfer. The wavelength jitter of laser mainly degrades the short-term stability of fiber-optic time transfer, while the wavelength drift of laser mainly has impact on the stability at the averaging time related to the cycle of wavelength drift. When the standard deviation of wavelength jitter of laser changes from (0.07, 0.05) pm to (0.27, 0.25) pm, the stability of 3000 km fiber-optic time transfer will deteriorate from 3 ps/s to 12 ps/s.