Two-dimensional gold decorated indium selenide for near-infrared and mid-infrared ultrafast photonics

•Decorated with gold nanoparticles, Indium selenide nanosheets exhibits excellent nonlinear absorption properties.•It is the shortest mode-locking pulse (507 fs) that researchers have achieved from 1.5 μm InSe-modulated fiber lasers.•It is the first demonstration of 2 μm mode-locking pulse in InSe-modulated fiber lasers.•With the help of dispersive Fourier transform technique, the breathing mode-locking state was observed real-timely.