Regulation of coupled dark-bright vector pulses in fiber lasers via intracavity weak birefringence management

In this work, the cross-polarization coupling of dark–bright vector pulses was comprehensively investigated through a combination of experiments and numerical simulations. Experimentally, based on a variety of soliton phenomena, including bright pulses, dark–bright vector pulses, and bright–dark–bright composite pulses, controllable switching between coherently and incoherently cross-polarization-coupled dark–bright vector pulse states was achieved by regulating the net intracavity birefringence. Numerical simulations are consistent with the experimental results, revealing that the net cavity birefringence and nonlinear effects jointly govern the cross-polarization coupling characteristics between orthogonally polarized pulses. This work provides clear physical insight into the polarization-dependent coupling dynamics of dark–bright vector pulses in fiber laser systems.