Fig. 1. (a) Flow chart of sample preparation and (b) single-beam Z-scan setup.

Fig. 2. XRD plots of (a) ITO, Sn nanofilm and (b) ITO/Sn samples synthesized according to different relative thickness ratios.

Fig. 3. AFM 3D images of (a) ITO 100 nm, (b) Sn 100 nm, (c) ITO 70 nm/Sn 30 nm, (d) ITO 50 nm/Sn 50 nm, and (e) ITO 30 nm/Sn 70 nm samples. (f) RMS value change of samples and (g) average diameter of samples.

Fig. 4. Optical (a) transmittance and (b) absorption profiles of ITO, Sn, and ITO/Sn films.

Fig. 5. (a), (b) Open aperture Z-scan measurements of ITO, Sn, and ITO/Sn composite films with different relative thickness ratios.

Fig. 6. Fitting of nonlinear absorption values (β) of monolayer ITO, Sn, and ITO/Sn composite films.

Fig. 7. FDTD simulated electric field distributions for (a) ITO, (b) Sn, and (c) ITO/Sn films.