Effect of gold nanoparticles in broadband near-infrared emission of Pr3+ doped B2O3–PbO–Bi2O3–GeO2 glass

Abstract

B2O3–PbO–Bi2O3–GeO2 glass doped with Pr3+ was synthesized and implanted with Au+ using energy of 300keV and fluence of 1 × 1016cm−2. Annealing at moderate temperature, below the glass transition temperature, induced nucleation and growth of gold nanoparticles confirmed by the corresponding absorption band in the visible range and by transmission electron microscopy. The average size of the gold nanoparticles was about 2.8nm. The annealing also induced the crystallization of a nanometer thick layer at the implanted surface of the sample due to the defects created by ion implantation. Structural and optical properties of the samples were characterized by X-Ray difraction, Raman spectroscopy, thermal analysis and absorption and luminescence spectroscopy. Broadband infrared emission was observed under 488nm excitation covering a wide region of the optical telecommunication window (1.3μm–1.7μm). The intensity of this band was enhanced after thermal annealing, probably due to the local field effect of gold nanoparticles. From the optical absorption measurements, Judd–Ofelt theory was applied to evaluate the phenomenological intensity parameters Ωλ (λ=2, 4 and 6) and radiative properties like transitions probabilities, radiative lifetimes, branching ratio and stimulated emission cross-section. The large stimulated emission cross section and broadband effective bandwidth indicate that Pr3+ doped B2O3–PbO–Bi2O3–GeO2 glass containing gold nanoparticles is promising for use in optical amplification.