Observation of Three Bound States From a Topological Insulator Mode-Locked Soliton Fiber Laser

We report on the generation of three types of bound states in a topological insulator-based mode-locked fiber laser. Benefiting from the excellent performance of the polyvinyl alcohol-based topological insulator saturable absorber (SA), we have achieved three types of bound solitons. The bound states exhibit different features both in spectra and autocorrelation traces, which was found to be caused by the different peak intensities and pulsewidths of two closed pulses within the bound states. The experimental phenomena were further confirmed by the numerical simulations. The results reveal an alternative method to roughly estimate the constructed solitons within bound states and indicate that the topological insulator could serve as a highly nonlinear SA for observing soliton dynamics in fiber lasers.