Experimental investigation on dark solitons formation in Figure-9 Yb doped fiber laser

Dark soliton is a promising tool in communication systems for its ability to preserve its good shape. This paper demonstrates the generation of dark soliton in an Yb-doped fiber laser with a compact figure-9 resonator based on the principle of nonlinear amplifying loop mirror. In this laser, when the polarization controller is located in the gain fiber or single-mode fiber, the generation of dark soliton, bright soliton and bright-dark soliton pair, as well as the transformation between them, can be realized. This experiment provides the evidence on the generation of dark soliton at 1 μm, and the results show that the figure-9 fiber laser may obtain dark soliton, bright soliton or bright-dark soliton pair by simply adjusting the PC, which is helpful to obtain dark-soliton pulses in fiber lasers.