Suppression of multi-period instabilities by third-order dispersion in mode-locked Yb-doped fiber lasers

摘要

Multi-period pulsing instabilities in a Yb-doped ring fiber laser with a mode-locking mechanism provided by nonlinear polarization rotation are studied by means of numerical simulations. The impact of the third-order dispersion (TOD) of cavity elements on dynamic instabilities of the stretched-pulse mode-locked regime is elucidated. Different instability types with symmetry-preserving and symmetry-breaking features are found in a wide range of cavity group velocity dispersion (GVD). At a large anomalous cavity GVD, where a stretched-pulse mode-locked regime borders the soliton regime, multi-period pulsing instabilities result from the development of new resonant subsidebands associated with unstable dispersive waves. When a cavity GVD approaches zero and resonant sidebands are suppressed, multi-period pulsing is caused by parametric instability of the frequencies near the spectrum center. It is demonstrated that TOD suppresses both symmetry-preserving and symmetry-breaking multi-period instabilities in the stretched-pulse regime. From the analysis of the spectral sidebands, we conclude that instability suppression is related with a modification of the resonant coupling between the mode-locked pulse and the phase-velocity as well as group-velocity-matched dispersive waves. (C) 2008 Optical Society of America.