Davinson M. da Silva

Frequency upconversion in Er3+ doped PbO–GeO2 glasses containing metallic nanoparticles

The authors report the infrared-to-visible frequency upconversion (UPC) process in Er3+ doped PbO–GeO2 glasses containing silver nanoparticles (NPs) with an average diameter of 2.2nm. The absorption spectra of the samples present a band centered at 470nm due to the surface plasmons associated with the NPs. The intensity of the band grows with increasing NP concentration. The experiments were performed by exciting the samples with a 980nm diode laser and observing the UPC emissions in the red-green region. The enhanced UPC intensity is attributed to the local field effect in the proximity of the NPs.

Influence of silver nanoparticles in the luminescence efficiency of Pr3+-doped tellurite glasses

We studied the influence of silver nanoparticles (NPs) in the luminescence properties of TeO2–PbO–GeO2 glass doped with trivalent praseodymium (Pr3+) ions. The experiments were performed with samples containing different concentrations of NPs controlled by heat treatment of the glass. The enhancement of the Stokes luminescence with the increase of the NPs concentration was observed for samples excited at 454nm. The influence of the NPs on the frequency upconversion (anti-Stokes) emissions of Pr3+ under excitation at 520nm was also investigated. In this case, enhancement of the emissions around 460 and 486nm was observed and the excitation pathway is also discussed.

Surface-plasmon-enhanced frequency upconversion in Pr3+ doped tellurium-oxide glasses containing silver nanoparticles

A frequency upconversion process in Pr3+ doped TeO2–ZnO glasses containing silver nanoparticles is studied under excitation with a nanosecond laser operating at 590 nm, in resonance with the H34→D12 transition. The excited Pr3+ ions exchange energy in the presence of the nanoparticles, originating efficient conversion from orange to blue. The enhancement in the intensity of the luminescence at ∼482 nm, corresponding to the P30→H34 transition, is due to the influence of the large local field on the Pr3+ ions, which are located near the metallic nanoparticles.

Enhanced luminescence of Tb3+/Eu3+ doped tellurium oxide glass containing silver nanostructures

We report on energy transfer studies in terbium (Tb3+)—europium (Eu3+) doped TeO2–ZnO–Na2O–PbO glass containing silver nanostructures. The samples excitation was made using ultraviolet radiation at 355 nm. Luminescence spectra were recorded from ≈480 to ≈700 nm. Enhanced Eu3+ luminescence at ≈590 nm (transition D50−F71) and ≈614 nm (transition D50−F72) are observed. The large luminescence enhancement was obtained due to the simultaneous contribution of the Tb3+–Eu3+ energy transfer and the contribution of the intensified local field on the Eu3+ ions located near silver nanostructures.

Frequency upconversion luminescence from Yb+3–Tm+3 codoped PbO–GeO2 glasses containing silver nanoparticles

Infrared-to-visible and infrared-to-infrared frequency upconversion processes in Yb3+–Tm3+ doped PbO–GeO2 glasses containing silver nanoparticles (NPs) were investigated. The experiments were performed by exciting the samples with a diode laser operating at 980 nm (in resonance with the Yb3+ transition F27/2→F25/2) and observing the photoluminescence (PL) in the visible and infrared regions due to energy transfer from Yb3+ to Tm3+ ions followed by excited state absorption in the Tm3+ ions. The intensified local field in the vicinity of the metallic NPs contributes for enhancement in the PL intensity at 480 nm (Tm3+:G14→H36) and at 800 nm (Tm3+:H34→H36).

Luminescence of Tb3+ doped TeO2–ZnO–Na2O–PbO glasses containing silver nanoparticles

Luminescence properties of Tb3+ doped TeO2–ZnO–Na2O–PbO glasses containing silver nanoparticles (NPs) were investigated. The absorption band due to the surface plasmon resonance in the NPs was observed. Its amplitude increases with the heat treatment of the samples that controls the nucleation of the NPs. Tb3+ emission bands centered at ≈485, ≈550, ≈585, and ≈623 nm were detected for excitation at 377 nm. The whole spectrum is intensified by the appropriate annealing time of the samples. Enhancement by ≈200% of the Tb3+ luminescence at 550 nm was observed for samples annealed at 270 °C during 62 h. This enhancement effect is due to the local field amplitude that increases with the amount of silver NPs and their aggregates.

Influence of silver nanoparticles on the infrared-to-visible frequency upconversion in Tm3+/Er3+/Yb3+ doped GeO2-PbO glass

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 nucleatio...

Thermo-optical properties of tellurite glasses doped with Eu3+ and Au nanoparticles

This work presents a study of tellurite glasses doped with Eu3+ and Au nanoparticles. Luminescence of Eu3+ ions in the yellow?red region was examined as a function of Au nanoparticles concentration, while the thermal lens technique furnished the thermal diffusivity of the samples. The influence of the nanoparticles concentration on the thermal diffusivity of the glass and the Eu3+ luminescence is discussed.

Enhanced Optical Properties of Germanate and Tellurite Glasses Containing Metal or Semiconductor Nanoparticles

Germanium- and tellurium-based glasses have been largely studied due to their recognized potential for photonics. In this paper, we review our recent studies that include the investigation of the Stokes and anti-Stokes photoluminescence (PL) in different glass systems containing metallic and semiconductor nanoparticles (NPs). In the case of the samples with metallic NPs, the enhanced PL was attributed to the increased local field on the rare-earth ions located in the proximity of the NPs and/or the energy transfer from the metallic NPs to the rare-earth ions. For the glasses containing silicon NPs, the PL enhancement was mainly due to the energy transfer from the NPs to the Er3+ ions. The nonlinear (NL) optical properties of PbO-GeO2 films containing gold NPs were also investigated. The experiments in the pico- and subpicosecond regimes revealed enhanced values of the NL refractive indices and large NL absorption coefficients in comparison with the films without gold NPs. The reported experiments demonstrate that germanate and tellurite glasses, having appropriate rare-earth ions doping and NPs concentration, are strong candidates for PL-based devices, all-optical switches, and optical limiting.

Influence of gold nanoparticles on the 1.53 µm optical gain in Er 3+ /Yb 3+ : PbO-GeO 2 RIB waveguides

We report the fabrication of waveguide amplifiers produced by RF-sputtering, using a PbO-GeO(2) glass (PGO glass) film codoped with Er(3+)/Yb(3+). RIB waveguides were obtained from PGO thin films using optical lithography followed by reactive ion etching process. The optical losses in the waveguide were ≈1.0 dB/cm and the maximum internal gain at 1.53 µm, with excitation at 980 nm, was 3 dB/cm. Nanostructured gold films deposited on the waveguides enhanced the Er(3+) ions photoluminescence (PL) by ≈400% in the red region and ≈30% in the infrared, under 980 nm pumping. The optical gain was enhanced and reached 6.5 dB/cm. The results demonstrate that the PGO waveguides, with or without gold nanoparticles, are promising for integrated photonics.