Spatiotemporal dynamics of dissipative solitons in anomalous dispersion few-mode fiber lasers

All-fiber spatiotemporal mode-locked (STML) lasers offer exceptional advantages in compactness and low-cost. The anomalous dispersion region, which includes the dispersive waves and the complex nonlinear spatiotemporal dynamics, has attracted considerable attention in recent years. By utilizing the strong spatial filtering and the low mode dispersion of gradient refractive index few-mode fiber (GIMF), we experimentally achieved spatiotemporal mode-locking in an anomalous dispersion few-mode all-fiber laser, uncovering dispersive wave mechanics related to mode composition with polarization sampling method. Through the numerical model of spatiotemporal mode-locking, we further analyze the spatiotemporal dynamics of few-mode fiber laser in anomalous dispersion area, demonstrating distinct characteristics of dispersive waves between higher-order and lower-order modes, and systematically revealing the dynamic process of pulse evolution in different modes inside the cavity. Additionally, we investigate the impact of different mode components on mode-locking by adjusting the dislocation between the gain fiber and the GIMF. The implementation of few-mode fiber lasers may open up new avenues for information capacity, high pulse energy generation, and spatiotemporal coherent optical fields.