Few-layer bismuthene for robust ultrafast photonics in C-Band optical communications.

The ultrafast photonics of different conventional two dimensional (2-D) materials have been studied intensively. Few-layer structure bismuthene has been reported as a new type 2-D material with high efficient electronic, strong mechanics, and outstanding photonics properties. In this paper, a robust ultrafast pulse generation in communications-Band (C-Band) based on few-layer bismuthene has been reported for the first time to the best of our knowledge. The characteristics and the ultrafast optical nonlinear properties of few-layer bismuthene have been investigated experimentally. The optical induced deposition method is employed to fabricate the saturable absorber based on bismuthene (BiSA). Most importantly, we also apply BiSA for the ultrafast photonics applications, which demonstrates that a high-splitting-threshold robust ultrafast fiber laser with 1.3-ps pulse duration at 1531 nm has been obtained in the experiments. Even though we increase the pump power from the self-starting threshold (i.e. 86 mW) to 314 mW, the soliton pulse will not be splitting. Moreover, the high splitting threshold laser operation can be achieved stably even if the lasers exposed in the air for at least half a year. It is demonstrated that the proposed bismuthene nonlinear components can be potentially applied in the optical communications with C-Band (i.e. 1530 -1565 nm wavelength) to broaden communications window.