Abstract
Alkali borate-based glasses containing Eu
2
O
3
embedded with different concentration of AuCl
3
were fabricated by melting and quenching process. The transmission electron microscopic measurements revealed morphology of the gold nanoparticles (NPs) embedded in glasses. The nonlinear optical features have been studied using
Z
-scan at 532 nm excitation utilizing nanosecond laser pulses. The nonlinear absorption and refraction features were ascertained by operating the
Z
-scan technique in open aperture (OA) and closed aperture (CA) configurations, respectively. OA and CA
Z
-scan signatures unveiled the presence of two-photon absorption and self-focusing refraction nonlinearities, respectively. In the AuCl
3
varied glasses, the highest value of the third-order nonlinear susceptibility (
χ
(3)
) (8.01 × 10
‒13
esu) was obtained for 0.02 mol% of AuCl
3
doped glasses. This optimized system annealed at 450 °C for diverse schedules to tune
χ
(3)
of glass matrices to higher value (for 30 h of annealing, the
χ
(3)
found to be 12.77 × 10
‒13
esu). The enhancement in
χ
(3)
with respect to the gold NPs and with respect to heat treatment schedules was regarded to electric field generated by gold NPs near the Eu
3+
ions. However, the results were adversely attenuated at higher heat treatment durations (at 40 h) due to non-uniform local field generated by larger size gold NPs. The nonlinear optical results suggest that the heavily AuCl
3
loaded glass and heat treated at 450 °C for 30 h durations are beneficial for applications in nonlinear photonic devices in the visible region.