Design And Implementation Of The Multi-Function Time-Frequency Transmission System

Highly stable time-frequency delivery technology is widely applied in the field of military and civil research, which deeply affects our life from different aspects. Time-frequency transmission technology over the optical fiber has many advantages such as low noise, low loss and large bandwidth, which can be regarded as a technology with the potential to significantly improve the performance of the systems in radio astronomy and aerospace fields.In this paper, we introduce some key technologies in the time-frequency transmission systems, describe the characteristics of different transmission technologies and analyze the test methods of performances of the transmission system. The optical fiber suffers from the environment perturbations, such as mechanical vibration and temperature fluctuations, which degrade the time and phase stability. Then we discuss the key technique about how to compensate phase error of the time/frequency signals in the transmission system, and the theory and implementation of optical compensation methods are also addressed.In this paper, we deliver a stable time/frequency signal over a long fiber link by using the optical phase compensation method. Besides, we propose a novel multi-function time/frequency transmission system based on the wavelength division multiplexing (WDM) technology. Because all different function signals pass through the same fiber link, only one active compensating element is used in the link to ensure the high accuracy transmission. Experimentally, we demonstrate that the time deviation of the time signal over5-km fiber is0.783ps at1000-s average. The frequency stability is1.87×10-15in averaging time of1000-s over the same fiber link.