NiS₂ as a broadband saturable absorber for ultrafast pulse lasers

Nickel disulfide (NiS₂) has recently been found to possess strong nonlinear saturable absorption properties. This feature is highly attractive for nonlinear photonics applications. Ultrafast pulse generation is successfully demonstrated in this article for both Ytterbium- and Erbium-doped fibre lasers using micro-fibre deposited nickel disulfide (NiS₂) as a saturable absorber (SA). The fabricated SA device has a modulation depth of 23% at 1.06 μm and 30.8% at 1.55 μm. Stable dissipative soliton operation was achieved at 1064.5 nm with a pulse duration of 11.7 ps and another stable conventional soliton pulse train was also obtained at 1560.2 nm with a pulse duration of 524 fs. These results demonstrate that the microfibre-based NiS₂ has a broadband nonlinear response and can function as an efficient SA, therefore it has significant potential for use in ultrafast laser pulse generation.