Third-order nonlinear optical properties of chemically synthesized copper oxide nanosheets

Copper oxide (CuO) nanosheets were obtained by a quick-precipitation method using Cu(NO3)2 and NaOH in the presence of polyvinylpyrrolidone (PVP). Different sizes of CuO nanosheets were achieved by varying the PVP concentration. The crystal structure, morphology, and optical properties of the CuO nanosheets were characterized by X-ray diffraction, transmission electron microscopy, and diffuse reflectance spectroscopy. Higher PVP concentrations produced CuO nanosheets with enhanced crystalline structure, reduced particle size, and enlarged band gap. Nonlinear optical characteristics were examined by the Z-scan technique using a blue continuous wave laser beam operated at 405 nm. Increased PVP concentration from 0.5 wt% to 5 wt% was found to increase the nonlinear refractive index from −2.157×10−11 to −5.495×10−11.