Nonlinear refractive index enhancement of Nd3+ ions loaded borate glasses in the near–infrared region by silver nanoparticles

Abstract

The study presents an evaluation and in–depth discussion of the efficacy of silver (Ag) nanoparticles (NPs) concentration on the third–order nonlinear optical (NLO) proeprties of borate glasses. The optical absorption data revealed Nd3+ ions and Ag NPs to be present in the studied glasses. Measurements carried out on the tested glass through transmission electron microscopy revealed spherical–shaped NPs with a median size of ∼16.53 nm (analyzed using the ImageJ software). Open and closed aperture Z–scan configurations were employed to ascertain the attributes of NLO absorption and refraction, respectively. Open–aperture Z–scan data revelaed two–photon absorption nonlinearity in the studied glasses, while the closed aperture Z–scan data revealed self–focusing nonlinear refraction. With the increase in silver NPs concentration, the nonlinear refraction coefficient was significantly increased compared to the nonlinear absorption parameter. The results instantiate large concentrations of Ag NPs embedded in borate glasses bearing Nd3+ ions are suitable for all–optical switching applications that excel in their functioning in near–infrared spectral range.