A high stability, low noise RF distribution system

Abstract

Next generation linear colliders require high stability, low noise distribution of RF phase and timing signals. We describe a fiber-optics system that transmits phase at 357 MHz, at a 1500 nm wavelength, over a distance of 15 kilometers. Phase length errors in the transmission fiber are measured using the phase of the signal reflected from the fiber end. Corrections are performed by controlling the temperature of a 6-kilometer fiber spool placed in series with the main transmission fiber. This system has demonstrated a phase stability better than 10 femtoseconds per degree C, per kilometer, an improvement of a factor of >2000 relative to unstabilized fiber. This system uses standard low cost telecom fiber and components.