Based on the coupled Ginzburg-Landau equations and Jones matrices of the waveplates considered, a numerical model of an all-normal-dispersion fiber laser mode-locked by nonlinear polarization rotation has been proposed. The operating characteristics of the fiber laser discussed were studied numerically. It has been found that the proposed all-normal-dispersion mode-locked fiber laser (AND-MLFL) could deliver dissipative solitons (DSs) with a M-shaped and U-shaped spectrum, the splitting pulse with a divided spectrum and the amplifier similaritons. The evolution of the intra-cavity pulse and spectrum has been calculated under different regimes and the effects of group velocity dispersion (GVD) and nonlinearity are analyzed. When the fiber laser delivers DSs or causes pulse splitting, nonlinear effects dominate the pulse evolution. With the increase of the accumulated nonlinear phase shift, the operation states change from DS with a M-shaped spectrum to a U-shaped spectrum, and then to the splitting pulse. In the case of amplifier similaritons, both the GVD and nonlinearity play important roles in pulse evolution. The effect of nonlinear polarization rotation and filtering on the pulse reshaping has been analyzed. When the fiber laser delivers DSs with a M-shaped spectrum, the filter has a very weak effect on the pulse and on spectral reshaping. However, when the fiber laser operates in the amplifier similariton state, the filter plays a key role in pulse and spectral reshaping, whereas the nonlinear polarization rotation become less dominant. The dependence of the operational states on the filter bandwidth, fiber length, small signal gain coefficient and orientation of waveplates has also been calculated. A Yb-doped doubled-cladding fiber laser, mode-locked by nonlinear polarization rotation, has also been demonstrated and all of the four pulse regimes are obtained experimentally.

中文翻译：

---

四种不同脉冲状态下全正态色散环形光纤激光器的脉冲动力学


基于耦合的Ginzburg-Landau方程和波片的琼斯矩阵，提出了一种通过非线性偏振旋转锁模的全法向色散光纤激光器的数值模型。对所讨论的光纤激光器的工作特性进行了数值研究。研究发现，所提出的全法向色散锁模光纤激光器（AND-MLFL）可以提供具有 M 形和 U 形光谱的耗散孤子（DS）、具有分裂光谱的分裂脉冲和放大器相似之处。计算了不同状态下腔内脉冲和频谱的演变，并分析了群速度色散（GVD）和非线性的影响。当光纤激光器传输 DS 或引起脉冲分裂时，非线性效应在脉冲演化中占主导地位。随着累积非线性相移的增加，工作状态从M形谱的DS变为U形谱，再到分裂脉冲。在放大器相似的情况下，GVD 和非线性在脉冲演化中都起着重要作用。分析了非线性偏振旋转和滤波对脉冲整形的影响。当光纤激光器传输具有 M 形光谱的 DS 时，滤波器对脉冲和光谱整形的影响非常微弱。然而，当光纤激光器工作在放大器相似状态时，滤波器在脉冲和光谱整形中起着关键作用，而非线性偏振旋转则变得不那么占主导地位。还计算了工作状态对滤波器带宽、光纤长度、小信号增益系数和波片方向的依赖性。 还演示了一种通过非线性偏振旋转锁模的掺镱双包层光纤激光器，并且所有四种脉冲状态都是通过实验获得的。