Facile fabrication of wafer-scale MoS2 neat films with enhanced third-order nonlinear optical performance

Wafer-scale MoS2 neat films with controllable thicknesses were successfully fabricated by vacuum filtering liquid-exfoliated MoS2 dispersions. The obtained MoS2 filtered thin films were systematically characterized by UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM). It was found that the fabricated scalable MoS2 films have a smooth surface and high optical homogeneity verified by AFM and a collimated 532 nm beam, respectively. We investigated the ultrafast nonlinear optical (NLO) properties of the filtered films by an open aperture Z-scan method using 515 and 1030 nm femtosecond laser pulses. Saturable absorption was observed at both 515 and 1030 nm with the figure of merit (FOM) values as similar to 3.3 x 10(-12) esu cm and similar to 3.4 x 10(-14) esu cm, respectively. The observation of ultrafast NLO performance of the MoS2 filtered films indicates that vacuum filtration is a feasible method for the fabrication of optical thin films, which can be expanded to fabricate other two-dimensional films from the corresponding dispersions. This easy film fabrication technology will greatly enlarge the application of graphene analogues including graphene in photonic devices, especially of MoS2 as a saturable absorber.