Optical timing distribution system with femtosecond stability

Abstract

Stable timing distribution is a key technology for the many fields that use timing signals for synchronization. The frequency of the timing signal depends on the field and multiple timing signals are sometimes required. In our DWDM-based timing distribution system, phase deviation is detected by high-speed round-trip signal (10 GHz signal is used as this control signal). Fiber stretchers are controlled so as to minimize the phase deviation of the control signal. Multiple signals and the control signal are densely multiplexed and transmitted through the same stretchers. Therefore, the transmission of all signals is stabilized. This configuration provides a flexible platform for distributing various RF or microwave signals. As an example of arbitrary timing signals, a 1 GHz signal is transmitted over a length-stabilized 400-m fiber for more than 1 day. The recorded propagation time fluctuations are 10.4 and 2.8 fs rms for the 1 and 10 GHz signals, respectively. The Allan deviations are 2.7 ×