Biosynthesis, characterization and nonlinear optical response of spherical flake-shaped copper oxide nanostructures.

The copper oxide nanoparticles (CuO NPs) were synthesized via solution combustion approach with Bengal gram powder as a fuel. The XRD analysis confirms the monoclinic structure of CuO NPs. FT-IR spectrum reveals the formation of CuO NPs. SEM studies show that the NPs are nearly spherical, and the elemental composition was confirmed by EDAX. The absorption spectra revealed a direct optical band gap of 1.50 eV. DFT calculations were performed to determine the HOMO–LUMO energy bandgap and found to be 1.72 eV, which is in good agreement with the experimental value. The Z-scan technique was used to investigate the third-order nonlinear optical (NLO) characteristics using DPSS continuous wave laser (532 nm, 200 mW). A high reverse saturation absorption and negative nonlinear refractions were observed. Third-order NLO parameters β , n 2 and χ (3) were found to be 1 9. 6 × 1 0 − 5 cm/W, − 1. 1 2 × 1 0 − 8 cm2/W and 5. 9 7 × 1 0 − 7 esu, respectively. The CuO NPs also displayed strong optical limiting behavior with a limiting threshold of 2.11 kW/cm2. [ABSTRACT FROM AUTHOR]