Large-energy mode-locked ytterbium-doped linear-cavity fiber laser based on chemical vapor deposition-Bi2Se3 as a saturable absorber.

We reported on the generation of pulse bunch and large-energy dark pulses in a mode-locked ytterbium-doped linear-cavity fiber laser based on Bi₂Se₃ as a saturable absorber (SA). Bi₂Se₃ nanosheets were successfully synthesized by the chemical vapor deposition (CVD) method and transferred to the end facet of a fiber connector for the proposed SA. Its saturation intensity and modulation depth were measured to be 52 MW/cm² and 14.5%, respectively. By inserting the Bi₂Se₃-based SA into the Yb-doped all-fiber linear cavity, stable pulse bunches were observed. In addition, dark soliton operation with a maximum average output power of 32.6 mW and a pulse energy of 61.8 nJ were also achieved. To the best of our knowledge, this is the first demonstration of a dark soliton within a linear cavity with much larger pulse energy than previous works. Our study fully indicated that CVD-Bi₂Se₃ could be an excellent SA for achieving large-energy pulse operations.