Long-term Stabilization of Fiber Laser Using Phase-locking Technique with Ultra-low Phase Noise and Phase Drift

We review the conventional phase-locking technique in the long-term stabilization of the mode-locked fiber laser and investigate the phase noise limitation of the conventional technique. To break the limitation, we propose an improved phase-locking technique with an optic-microwave phase detector in achieving the ultra-low phase noise and phase drift. The mechanism and the theoretical model of the novel phase-locking technique are also discussed. The long-term stabilization experiments demonstrate that the improved technique can achieve the long-term stabilization for the MLFL with ultra-low phase noise and phase drift. The excellent locking performance of the improved phase-locking technique implies that this technique can be used to stabilize the mode-locked fiber laser with the highly stable H-master or optical clock without stability loss

Coupled-oscillator systems: efficient simulation with harmonic-balance based oscillator models

A two-level simulation methodology for coupled-oscillator systems is presented. The inner level corresponds to the harmonic-balance analysis of the elementary oscillator in free-running regime, so as to obtain a one-port reduced-order model. The outer level corresponds to the analysis of the coupled system, deriving a formulation that explicitly relates the oscillation-frequency deviation and the amplitude and phase distributions to magnitudes characterizing the coupling network and oscillator elements. A stability analysis based on this formulation is also carried out obtaining a mathematical condition that determines the stable phase-shift interval. The formulation provides valuable insight into the system behavior and allows the derivation of realistic criteria for an optimum coupled-system performance. The two-level analysis has been extended to injection-locked systems, which enables an investigation of the impact of the number of oscillator elements and relative position of the injection signal on the locking bandwidth.This work was supported by the Spanish Ministry of Economy and Competitiveness under Contract TEC2011-29264-C03-01