Phase stabilized RF reference signal dissemination over optical fiber employing instantaneous frequency control by VCO

Stable microwave reference signal transfer systems are required in communication systems, very long baseline interferometer (VLBI) radio astronomy applications, particle accelerators and metrologies. Radio over fiber (RoF) technique is one of candidates which realize precise microwave dissemination without degradation of stability. We developed the precision microwave signal dissemination system in which a fluctuation of phase caused by transmitting optical fiber thermal expansion. This system monitors a phase of the signal reflected at destination, and controls transmitting signal frequency using a voltage controlled oscillator (VCO). The measurement shows that the phase error is 0.098 deg (r.m.s) of the 1.0 GHz microwave signal in 1-km length single mode fiber over 10 hours.