锁模光纤激光器中隐形孤子脉动演化特性研究（特邀）

以锁模光纤激光器为研究平台，利用色散傅里叶变换技术，实时观察到调制频率成比例的三周期隐形孤子脉动现象。通过分析孤子的演化特性，笔者所在课题组认为孤子的调制不稳定性引起了色散波和孤子的参量耦合过程，导致了色散波和孤子的能量交换，从而产生了参量边带和隐形孤子脉动。部分能量在色散波和孤子间的交换使得孤子总能量几乎不变。因此这种孤子脉动难以通过时域脉冲序列分辨。此外，文中实验分析了隐形孤子脉动完整的演化路径，即仅通过增加泵浦功率使得脉动产生至消失的过程。与传统的可见脉动过程相比，这种隐形孤子脉动的调制周期随泵浦功率的变化较小。该工作不仅加强了对孤子脉动动力学现象的理解，还对锁模激光稳定性的提升具有重要意义。

Evolution of invisible soliton pulsation in a mode-locked fiber laser (Invited)

The real-time observation of the tripling periodic invisible soliton pulsation in a mode-locked fiber laser with the dispersive Fourier transformation technique was reported. Since the three modulation frequencies were commensurate, the soliton pulsating behavior exhibited good periodicity rather than quasi-periodicity. After analyzing the soliton pulsating evolution, it was identified that the soliton modulation instability caused the generation of parametric sidebands and pulsating instability. The parametric process between soliton and dispersive waves induced the energy exchange between them. Consequently, there was no obvious total soliton energy variation during the evolution of soliton pulsation. As a result, the invisible soliton pulsation could not be visualized directly by the pulse train. In addition, by merely increasing the pump power with other cavity parameters unchanged, the entire route from the invisible soliton pulsation generation to stable dual-soliton pulses was systematically analyzed. Compared with the conventional visible soliton pulsation, the modulation periodicities of the invisible soliton pulsation showed weaker variations along with the pump power elevation. Our work not only contributed to understand the soliton pulsating dynamics in depth but also provided great assist to the optimization of laser performance.