VSe2 nanosheets for ultrafast fiber lasers

In this work, we investigate VSe2 for generating femtosecond and large energy mode-locked laser pulses for the first time. Two types of VSe2 based saturable absorbers (SAs), microfiber-VSe2 and VSe2/polyvinyl alcohol (PVA), are prepared, which exhibit strong nonlinear optical characteristics with a modulation depth (Delta T) of 22.5% and 1.849%, respectively. In contrast to other transition metal dichalcogenides (TMDCs), theoretical calculations show that VSe2 is a metallic TMDC SA. With the implementation of microfiber-VSe2, conventional soliton mode-locking Er-doped fiber (EDF) laser is demonstrated with an ultrashort pulse duration of 910 fs. Based on VSe2/PVA, a large energy EDF laser is established. The maximum single pulse energy is 25.57 nJ. This study suggests that VSe2 possesses application potential in ultrafast photonics and provides a valuable strategy for the development of TMDC based devices with desirable optoelectronic properties.