Effect of different stabilizers on dispersion of gold nanoparticles in bismuth borosilicate glass and their intensity dependent nonlinear behaviour

Here, we report the role of different stabilizers (Eu2O3, EuF3 and KSCN) in stabilizing gold nanoparticles (AuNPs) embedded in Bismuth-Borosilicate glasses. The prepared nanocomposites are characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), UV–Visible transmission spectroscopy, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), ellipsometery and Z-scan. From FESEM, it has been observed that the morphology of AuNPs is highly dependent on the type of stabilizer. Also HRTEM confirms the covering of AuNPs by stabilizer that prevents the coagulation of NPs. The localized surface plasmon resonance related transmission dip is observed around 585 nm for glass containing Eu2O3 as a stabilizer. The linear and nonlinear refractive index of the prepared glasses is obtained from ellipsometery and Z-scan measurements, respectively. All the Z-scan measurements have been carried out at different input peak intensities varying from 1.9 to 14.38 GW/cm2. Nonlinear optical studies with open aperture Z-Scan shows the switching between saturable absorption and two photon absorption as the laser intensity is increased. The existence of third order nonlinearity has been detected using closed aperture Z-scan in the prepared glasses.