Few-layer bismuthene for 1-μm ultrafast laser applications

Bismuthene, as a new two-dimensional (2D) material made up of diazo metal elements, has drawn massive attention for its unique electronic, mechanical, and quantum properties. However, the nonlinear optical properties of bismuthene in 1-µm region, especially their applications for ultrafast photonics and internal ultrashort pulse dynamics, has seldom been explored yet. In this work, we investigate the few-layer bismuthene characterizations and apply it as a saturable absorber (SA) in a 1-μm ultrafast pulse generation. Thanks to the narrow bandgap of bismuthene and tapered fiber structure, A special noise like pulse has been obtained. The dynamics is also quite different from previous observed pulses, whose intensity ratio of coherent peak and envelope components is of around 5:4 from the autocorrelation trace. It’s demonstrated that the abnormal noise-like pulses contain more uniform-intensity sub pulses. This proposed pulsed fiber laser based on bismuthene SA source is well suitable for some applications such as material processing, optical logics etc.

251 fs pulse generation with a Nd3+-doped Ca3Gd2(BO3)4 disordered crystal

Autocorrelation trace and spectrum of the mode-locked pulses.