Phase Noise Characteristics of Fiber Lasers as Potential Ultra-Stable Master Oscillators

Fourth-generation light sources, such as the European X-Ray Free Electron Laser facility (XFEL), require timing signals distributed over distances of several kilometers with a timing jitter in the order of femtoseconds. The master clock for the proposed optical distribution system must operate with exceptionally low timing jitter. A promising approach is the use of a mode-locked laser that generates ultrastable pulses which are distributed via timing stabilized fiber links. Mode-locked Erbium-doped fiber lasers are attractive candidates, featuring very low noise at high frequencies. In this paper, we present a study of the phase noise of various mode-locked fiber lasers in view of their applicability as laser-based master oscillators for femtosecond-level timing distribution.