Nonlinear optical response of the SnS2 nanosheet-based multilayer film

It is an effective strategy for enhancing the nonlinear optical response of materials to construct multilayer film structures. A periodic SnS 2 /TiO 2 optical multilayer structure based on SnS 2 nanosheets and its nonlinear optical properties are measured by using an 800 nm femtosecond laser Z-scan technique. Experimental results indicate that the multilayer film exhibited saturable absorption and self-defocusing behavior. The equivalent nonlinear absorption coefficient ( β eff ) and nonlinear refractive index ( n 2 ) are enhanced toward −354.9 cm GW -1 and −7.8 × 10 −3 cm 2 GW -1 , respectively, corresponding to 3.2 and 2 fold those of SiO 2 :SnS 2 monolayer films with equivalent thickness. The enhancement is attributed to the synergistic effects of localized electric field increasement within the periodic SnS 2 layers and the band-edge shifting induced by refractive index modulation. The results demonstrate that the multilayer structure significantly enhances nonlinear optical performance of two-dimensional SnS 2 , highlighting its potential for advanced photonic applications such as lasers.