  Recently, in addition to exploring the application of new saturable absorber
devices in fiber lasers, soliton dynamics has also become a focus of current
research. In this article, we report an ultrashort pulse fiber laser based on
VSe2/GO nanocomposite and verify the formation process of soliton and soliton
molecules by the numerical simulation. The prepared VSe2/GO-based device shows
excellent saturable absorption characteristics with a modulation depth of 14.3%
and a saturation absorption intensity of 0.93MW/cm2. The conventional soliton
is obtained with pulse width of 573fs, which is currently the narrowest pulse
width based on VSe2-related material, and has a signal-to-noise ratio of 60.4
dB. In addition, the soliton molecules are realized based on the VSe2/GO for
the first time and have a pulse interval of ~2.2ps. We study the soliton
dynamics through numerical simulation and reveal that before the formation of
the soliton, it undergoes multiple nonlinear stages, such as soliton
mode-locking, soliton splitting, and soliton oscillation. Furthermore, the
results of numerical simulation are agreed well with the experimental data.
These results indicate that the VSe2/GO might be another promising saturable
absorber material for ultrafast photonics, and deepen the understanding of
soliton dynamics in ultrafast fiber lasers.
