MoS 2 /graphene nanocomposite films are fabricated by vacuum filtering with liquid-phase exfoliated MoS 2 / graphene suspension. The nanocomposite films are characterized by Raman spectroscopy, UV−vis spectroscopy, and atomic force microscopy, indicating the optical films with a large scale and high optical homogeneity. The enhanced saturable absorption of MoS 2 /graphene nanocomposite films compared with pristine MoS 2 film and graphene film is investigated using an open-aperture Z-scan technique with a femtosecond laser at 800 nm. The nonlinear absorption coefficient of MoS 2 /graphene nanocomposite film is ∼ −1217.8 cm/GW, which is larger than that of MoS 2 film (∼ −136.1 cm/GW) and graphene film (∼ −961.6 cm/GW) at the same condition. The imaginary part of the third-order nonlinear optical susceptibility of the nanocomposite film can reach Imχ (3) ∼ 10 −9 esu with a figure of merit ∼10 −14 esu cm, low saturable intensity (∼157.0 GW/cm 2 ), and high modulation length (∼32%). A coupling model is considered in order to understand the nonlinear absorption properties of MoS 2 /graphene nanocomposite films, which suggest the enhancement can be attributed to charge transfer between MoS 2 and graphene. The results pave the way for the design of nonlinear optical properties with two-dimensional materials for good performance of optical switches or mode lockers based on saturable absorbers.

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