Observation of four self-sweeping regimes in a single-mode bi-directional ytterbium-doped fiber ring laser

In this work, for the first time, four self-sweeping regimes in a single-mode bi-directional ytterbium-doped fiber ring laser are observed by adjusting the polarization controller (PC): normal self-sweeping, reverse self-sweeping, mixed state, and wavelength stop state. In addition, regulating the PC can artificially selectively make the laser operate in normal self-sweeping or reverse self-sweeping within a certain pump power range, and their self-sweeping characteristics (e.g., sweeping rate, sweeping range, etc.) and intensity dynamics are investigated in detail, respectively. In conclusion, we can flexibly regulate the sweeping direction and sweeping characteristics of the bi-directional self-sweeping fiber ring laser in a simple approach by adjusting the PC, which is potentially valuable for its practical application.