Preparation and the third-order optical nonlinearities of the sodium borosilicate glass doped with Cu7.2S4 quantum dots

The sodium borosilicate glass doped with Cu7.2S4 quantum dots was prepared by using both sol–gel and atmosphere control methods. The formation mechanism and the microstructure of the glass were examined using differential thermal analysis and thermal gravimeter (TG-DTA), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), energy dispersive X-ray spectra (EDX), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED). The results revealed that Cu7.2S4 quantum dots in orthorhombic crystal system had formed in the glass, and the size ranged from 9 nm to 21 nm. In addition, Z-scan technique was used to measure the third-order optical nonlinearities of the glass. The results indicated that the third-order optical nonlinear refractive index γ, the absorption coefficient β, and the susceptibility χ(3) of the glass were 1.11 × 10− 15 m2/W, 8.91 × 10− 9 m/W, and 6.91 × 10− 10 esu, respectively.