Optically driven black phosphorus as a saturable absorber for mode-locked laser pulse generation

Black phosphorus (BP) is a very promising two-dimensional material as a saturable absorber for ultrashort pulse generation especially in telecommunication bands due to its ultrafast dynamic response and strong resonant absorption in the near-infrared wavelength range. However, the current fabrication methods of BP saturable absorbers are very complex and not suitable for practical large-scale production. We have successfully deposited BP with a thickness of ∼25 nm onto the fiber end facet as a saturable absorber by a simple optically driven deposition method. The BP saturable absorber shows excellent mode-locking performance with a stable pulse train repetition of 1.843 MHz and pulse duration of 117.6 ns.