Role of Sm in tuning the third-order nonlinear optical properties of spray coated Sn1-xSmxO2 films

In this work, the different physical and optical properties of spray coated nanostructured Sn1-xSmxO2 (x = 0.0 to 0.1) films were analyzed using various characterization techniques. All the films exhibited tetragonal structure with (1 1 0) as the prominent plane. The doping in general reduced the crystalline nature of the films along with narrowing of the bandgap values. Among the doped films, the most transmitting film was the 2 at.% Sm doped film, whereas the most crystalline was the 7 at.% Sm doped film. The fibrous morphology changed to distinct grains with the increase in Sm concentration. The oxidation states of the constituent elements were confirmed using X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) intensity was influenced by doping and emissions corresponding to the host SnO2 lattice were observed in the UV and visible regions. The PL emissions corresponding to the Sm ion transitions could not be found in the spectra. All the films exhibited third-order nonlinear optical nature with reverse saturable absorption. The suitability of these films as optical limiting material was identified. The magnitude of third-order nonlinear susceptibility χ(3) was also estimated to be in the range of 10−3-10−2 esu and the least optical limiting threshold was shown by Sn0.93Sm0.07O2 films.