Sol-gel synthesis and third-order optical nonlinearity of Au nanoparticles doped monolithic glass

Gold nanoparticles (Au NPs) doped monolithic and transparent sodium borosilicate glass has been synthesized by both sol-gel and atmosphere control heat treatment methods. Fourier transform infrared (FTIR) spectra in the wavenumber range of 400 to 4000 cm−1 were applied to collect variation information of surface groups of the samples in the sintering process. The microstructure of Au NPs in the glass was characterized by means of X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). Meanwhile, the linear optical properties of the glass were analyzed by UV-vis spectrometer between the wavelength of 300 and 1000 nm, and a broad absorption band around 600 nm was observed. The third-order nonlinear optical properties of the glass were investigated by using Z-scan technique at the wavelength of 800 nm, pulse duration of 190 fs, and repetition rate of 20 Hz. The glass showed saturable absorption and self-focusing nonlinear refraction, and the optical nonlinear susceptibility χ (3) was estimated to be 1.7 × 10−14 esu, with the single-pulse energy of 1 μJ.