Nonlinear optical properties of gold nanoparticles containing borate glasses at spectral region of surface plasmon resonance

Herein, we subjected the sodium borate glass activated with gold nanoparticles (NPs) to thermal treatment at 500 °C for different holding time to improve their nonlinear optical (NLO) characteristics in visible spectral region. The linear optical density and microscopic measurements confirmed the presence gold NPs in the glass. The outcomes also divulged the growth of Au NPs with an annealing schedule. The NLO attributes were ascertained through the Z–scan method, in which the samples were pumped at 532 nm utilizing nanosecond laser pulses fired at a rate of 1 kHz. Open aperture Z–scan measurements disclosed the existence of two–photon absorption nonlinearity, whereas closed aperture Z–scan experiments revealed the presence of self–defocusing nonlinear refraction in the studied glasses. The measurements unveiled the enhance trend of two–photon absorption and nonlinear refraction coefficients of glass host with thermal holding time owing to the growth of NPs. It was identified that the titled glass embedded with gold NPs annealed for 7 h at 500 °C owes maximum NLO features. Therefore, NBAu–7 glass examined in the current sturdy is beneficial for bio–imaging, optical limiting and NLO nanophotonic applications.