Observation of multimode solitons in the spatiotemporal mode-locked fiber laser with different chromatic dispersion

In this letter, we have experimentally observed the spatiotemporal mode-locking (STML) in an all-fiber multimode laser with different chromatic dispersions at 1.5μm. In the anomalous dispersion regime, not only the stable multimode conventional solitons (CSs), but also the loosely bound solitons (BSs) are achieved, with specific set of polarization controller (PC) and the state of multimode fiber (MMF) segment. Similarly, in the normal dispersion regime, the oscillator generates the MM dissipative solitons (DSs) or the BSs. Moreover, the operation wavelength of these two types of solitons in normal dispersion regime can be converted between ∼1530 nm and ∼1550 nm due to the birefringence filter effect. The evolution of the beam profiles is investigated, and we found that the state of the MMF plays a key role in energy distribution of the MM solitons. We believe that our results contribute to the further understanding and exploring of nonlinear characteristics in the STML fiber laser systems.