Assessment of the third order nonlinear optical susceptibility of V2−xCoxO5 (x = 0.0, 0.05, 0.10, 0.20) thin film via Z-scan technique.

Thin films of V2O5:Co nanocomposite were deposited by the thermal deposition method. Structural analyses show that all the samples had single orthorhombic phase of α-V2O5:Co. In addition, doping V2O5 with Co caused to the slightly shift of XRD peak positions to the lower angles which is due to the increase of interatomic distances. The nanoparticle size of V2−xCoxO5 (x = 0–0.2) increased with Co doping from 12 nm for x = 0.05–30 nm for x = 0.2. Moreover, the optical bandgap of samples increased from 3.08 for x = 0–3.35 eV for x = 0.2 which can be due to the surface and interface effects inducing a gap widening. The nonlinear optical properties of V2−xCoxO5 thin films were studied using the Z-scan technique. An increment has been observed in the nonlinear responses of all samples upon augmenting the laser power intensity. The nonlinear absorption (saturation absorption (SA)) and nonlinear refraction responses had the highest amount of transmittance (4.64 cmW−1 and 8.49 × 10−4 cm2W−1) for x = 0.20 and the lowest amount of transmittance (3.26 cmW−1 and 3.96 × 10−4 cm2W−1) for x = 0.00, respectively. In addition, both the self-defocusing and saturable absorption were dominant phenomena in the nonlinear refractive index and nonlinear absorption coefficient of the samples. [ABSTRACT FROM AUTHOR]