Asynchronous Harmonic Mode Locking in an All-Normal Dispersion Yb-Doped Fiber Laser

We present detailed experimental and theoretical results to demonstrate the possibility of asynchronous harmonic mode locking in an all-normal dispersion fiber laser. In contrast to asynchronous soliton mode-locking operation in the anomalous dispersion regime, more profound laser dynamics are found. The experimentally demonstrated 10-GHz asynchronous harmonic mode-locked Yb-doped fiber laser exhibits an excellent super-mode noise suppression ratio in the RF spectrum with picosecond output pulsewidth.