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The influence of silver nanoparticles (NPs) on the frequency upconversion luminescence in Er3+ doped TeO2-WO3-Bi2O3 glasses is reported. The effect of the NPs on the Er3+ luminescence was controlled by appropriate heat-treatment of the samples. Enhancement up to 700% was obtained for the upconverted emissions at 527, 550, and 660 nm, when a laser at 980 nm is used for excitation. Since the laser frequency is far from the NPs surface plasmon resonance frequency, the luminescence enhancement is attributed to the local field increase in the proximity of the NPs and not to energy transfer from the NPs to the emitters as is usually reported. This is the first time that the effect is investigated for tellurite-tungstate-bismutate glasses and the enhancement observed is the largest reported for a tellurium oxide based glass. [ABSTRACT FROM AUTHOR]

Luminescence properties of Eu3+ doped germanate glasses containing either silver or gold nanoparticles (NPs) were investigated for excitation at 405 nm. Enhanced emissions and luminescence quenching of the Eu3+ transitions in the range from 570 to 720 nm were observed for samples having various concentrations of metallic NPs. Electric-dipole and magnetic-dipole transitions that originate from the Eu3+ level 5D0 exhibit large enhancement due to the presence of the metallic NPs. The results suggest that the magnetic response of rare-earth doped metal-dielectric composites at optical frequencies can be as strong as their electric response due to the confinement of the optical magnetic field. [ABSTRACT FROM AUTHOR]

Several studies are conducted to determine the various luminescence properties of the [Eu.sup.3+] doped germanate glasses with silver or gold nanoparticles. The various effects of these metallic nanoparticles on the electric- and magnetic-dipole transitions taking place in the glasses are also explained.

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We investigated the influence of silver nanoparticles (NPs) on the infrared-to-visible frequency upconversion (UC) in GeO2-PbO glass triply doped with thulium (Tm3+), erbium (Er3+), and ytterbium (Yb3+) ions. The NPs were nucleated inside the samples by heat-treatment of the germanate glass that included small amount of AgNO3 in the starting composition. When excited at 980 nm, in resonance with the Yb3+ transition 2F7/2 → 2F5/2, the samples emit blue light at ≈477 nm due to the Tm3+ ions, green light at ≈530 nm and ≈550 nm due to the Er3+ ions, and red light at ≈652 nm due to Tm3+ and at ≈660 nm due to the Er3+ ions. Due to the silver NPs, the photoluminescence intensity grows by ≈60% in comparison with a sample having the same composition but without silver NPs. This is the first time that UC enhancement due to metallic NPs is investigated for a triply rare-earth (RE) doped glass. The results indicate the possibility of development of more efficient three-dimensional RE based color displays by nucleation of metallic particles in the glass host. [ABSTRACT FROM AUTHOR]

We report large photoluminescence (PL) enhancement in Eu3+-doped GeO2–Bi2O3 glasses containing gold nanoparticles (NPs). Growth of ≈1000% in the PL intensity corresponding to the Eu3+ transition 5D0→7F2, at 614 nm, was observed in comparison with a reference sample that does not contain gold NPs. Other PL bands from 580 to 700 nm are also enhanced. The enhancement of the PL intensity is attributed to the increased local field in the Eu3+ locations due to the presence of the NPs and the energy transfer from the excited NPs to the Eu3+ ions. [ABSTRACT FROM AUTHOR]

Abstract: Infrared-to-visible frequency upconversion (UC) in Nd3+-doped PbO–GeO2 (PGO) glasses containing silver nanoparticles (NPs) was investigated. The excitation was made at 805nm, in resonance with the Nd3+ transition 4I9/2 → 4F5/2. Photoluminescence (PL) bands centered at 535nm, 600nm and 670nm were observed corresponding to the electronic transitions 4G7/2 → 4I9/2, [4G7/2 → 4I11/2, 4G5/2 → 4I9/2], and [4G7/2 → 4I13/2, 4G5/2 → 4I11/2], respectively. The quadratic dependence of the UC intensity versus the laser intensity indicates that two laser photons contribute for the emission of each upconverted photon. The results show for the first time that the nucleation of silver NPs in Nd3+-doped PGO glasses contributes to increase the UC efficiency and the PL enhancement reached ≈50% for the samples with the maximum concentration of NPs. [Copyright &y& Elsevier]