Wavelength-switchable vector soliton molecular complexes in passively mode-locked fiber lasers

Solitons, which can form soliton molecules analogous to the molecular structure of matter, are currently being investigated in multi-wavelength passively mode-locked fiber lasers. In this paper, four-soliton molecules are numerically obtained in a passively mode-locked fiber laser with all-normal dispersion. It is found that a number of structures of soliton molecular complexes can be created by adjusting polarization. It is possible to create four-soliton molecules of single-wavelength featuring vibrating and sliding phase dynamics. Furthermore, three different types of dual-wavelength four-soliton molecules can be achieved. Importantly, it is found that the wavelength spacing is not affected by the polarization shift, but only the existence of multiple wavelengths is determined. This work contributes to the generation of dual-wavelength pulses and the creation of soliton molecular complexes with diverse structural compositions. •A novel design based on a Yb-doped passively mode-locked fiber laser is proposed for wavelength-switchable soliton molecules.•The group velocity-locked vector soliton molecules of single-wavelength feature vibrating and sliding phase dynamics.•Three different types of dual-wavelength four-soliton molecules can be achieved, namely ‘1+3’, ‘2+2’, and ‘3+1’.•The variety of polarization direction θ causes a filtering effect, generating the dual-wavelength pulses.