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

The ultrafast photonics of different conventional two-dimensional (2D) materials have been studied intensively. Few-layer structure bismuthene has been reported as a new type of 2D material with high efficient electronics, 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. 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 utilize BiSA for the ultrafast photonics, 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 does not split. Moreover, the high-splitting-threshold laser operation can be achieved stably even if the lasers are exposed in air for at least half a year. It is demonstrated that the proposed bismuthene nonlinear components can be potentially applied to the optical communications with C-Band (i.e. 1530-1565 nm wavelength) to broaden the communications window.