Fiber based multiple-access stable radio frequency phase delivery

Phase-stable radio frequency (RF) transfer attracts a growing research interest and attention in recent years, and transferring high stable RF signal to multiple places is greatly needed in many important applications such as frequency synchronization for very long base-line interferometry and connected-element interferometry in radio astronomy. [1]. For example, the Atacama Large Millimeter Array (ALMA) radio astronomy project is consist of an array of up to 64 antennas, and in order to achieve the unprecedented sensitivity and angular resolution, requires the local oscillator reference signal arriving at remote antennas with a maximum path length up to 18 kilometers must be stabilized under one picosecond [2]. The optical fiber link is a promising method for long-distance highly stable frequency distribution, however it suffers from the environment perturbations such as physical vibration and temperature fluctuations, which degrade the phase stability to be delivered [3].