Danilo Manzani

Localized surface plasmon resonance interaction with Er3+-doped tellurite glass

We show the annealing effect on silver and Erbium-doped tellurite glasses in the formation of nanoparticles (NPs) of silver, produced by the reduction of silver (Ag+ → Ag0), aiming to an fluorescence enhancement. The absorption spectra show typical Localized Surface Plasmon Resonance (LSPR) band of Ag0 NP in addition to the distinctive absorption peaks of Er3+ ions. Both observations demonstrate that the photoluminescence enhancement is due to the coupling of dipoles formed by NPs with the Er3+ 4I(13/2) → 4I(15/2) transition. This plasmon energy transfer to the Er3+ ions was observed in the fluorescence spectrum with a blue-shift of the peaks.

Orange emission in Pr3+-doped fluoroindate glasses

We synthesize and study the properties of praseodymium doped fluoroindate glasses. Glass compositions with praseodymium molar concentrations up to 5% were obtained with good optical quality. Thermal, optical, and luminescence properties are investigated. Judd–Ofelt analysis is used to determine radiative lifetime and emission cross-section of the orange transition originating from the 3P0 level. We find that these glasses are good candidates for the realization of blue diode laser pumped orange lasers for quantum information processing applications.

A portable luminescent thermometer based on green up-conversion emission of Er 3+ /Yb 3+ co-doped tellurite glass

The determination of temperature is essential in many applications in the biomedical, technological, and industrial fields. Optical thermometry appears to be an excellent alternative for conventional electric temperature sensors because it is a non-contact method that offers a fast response, electromagnetic passivity, and high temperature sensitivity. In this paper, we propose an optical thermometer probe comprising an Er3+/Yb3+ co-doped tellurite glass attached to the tip of an optical fibre and optically coupled to a laser source and a portable USB spectrometer. The ratio of the up-conversion green emission integrated peak areas when excited at 980 nm was temperature dependent, and it was used to calibrate the thermometer. The thermometer was operated in the range of 5–50 °C and 50–200 °C, and it revealed excellent linearity (r2 > 0.99), suitable accuracy, and precisions of ±0.5 and ±1.1 °C, respectively. By optimizing Er3+ concentration, we could obtain the high green emission intensity, and in turn, high thermal sensitivity for the probe. The probe fabricated in the study exhibited suitable properties for its application as a temperature sensor and superior performance compared to other Er3+ -based optical thermometers in terms of thermal sensitivity.

Bacterial cellulose from glucanacetobacter xylinus: Preparation, properties and applications

Sao Paulo State University Institute of Chemistry Dept. of General and Inorganic Chemistry, R. Prof. Francisco Degni, s/n, Araraquara, SP

Study of Er3+ fluorescence on tellurite glasses containing Ag nanoparticles

Optical characteristics of tellurite glasses containing silver nanoparticles (NPs) and the influence on the emission spectrum of Er3+ ions were studied. The transitions 4f 4f from erbium ions, mainly the 4I13/2 → 4I15/2 transition that involve upconversion energy process, have a strongly dependence with the chemical structure of the rare earth ion. In the present work, silver nanparticles (NPs) embedded in the host vitreous material, show a significant enhance (or quenching) on the erbium fluorescence due the long-range electromagnetic interaction between the plasmon surface energy of the Ag NPs (Localized Surface Plasmon Resonance -LSPR) and the Er3+ ions.

Yb 3+ , Tm 3+ and Ho 3+ triply-doped tellurite core-cladding optical fiber for white light generation

Tellurite glass is proposed as a host for Yb3+, Tm3+ and Ho3+ triply doped optical fiber and, in this work, a new multimode optical fiber with triply-doped core was fabricated. We report results on the processing and characterization of tellurite-based glass preforms and fibers. Cr3+ was used as tracer to assess core quality and uniformity across 60 mm length preform. By Raman fluorescence of Tm3+ ions contained into the core, we also mapped the interface between core and cladding that reveals an interface around 45 μm for a 10.11 mm of preform. For triply-doped core fiber excited at 980 nm, we generated white light radiation. The chromaticity diagram showed the multicolor emission and the color tunability of the triply-doped core optical fiber.

Nonresonant third-order nonlinear properties of NaPO3―WO3―Bi2O3 glasses in the near infrared

n2, was 10 �15 cm 2 / W and the NL absorption coefficient, 2, varied from 0.3 to 0.5 cm/GW for WO3 concentrations varying from 20% to 50%. The experiments in the infrared did not show relevant NL behavior for WO3 concentrations smaller than 50%. In this paper, we report on the third-order nonlinearity of NaPO3 –W O3 –B i2O3 glasses that present large NL response in the near infrared. The presence of Bi2O3 instead of BaF2 in the glass composition contributes for the increase in the NL response because of the larger Bi2O3 polarizability. The samples prepared have good optical quality, they are stable against moisture, and have large optical damage threshold. The experiments performed in the infrared indicate large values of n2 for the different compositions investigated. Two variations in the Z-scan technique at 1064 and 800 nm, with picosecond and femtosecond laser pulses, respectively, were applied for characterization of the samples. From the experiments, we determine n2 10 �15 cm 2 / W, one order of magnitude larger than silica, and negligible NL absorption coefficient. Figures of merit for all-optical switching were determined using the NL parameters measured and the results indicate large potential of NaPO3 –W O3 –B i2O3 glasses for photonic devices in the near infrared.

The role of Bi2O3 on the thermal, structural and optical properties of tungsten-phosphate glasses

Glasses in the ternary system (70 - x)NaPO(3)-30WO(3)-xBi(2)O(3), with x = 0-30 mol %, were prepared by the conventional melt-quenching technique. X-ray diffraction (XRD) measurements were performed to confirm the noncrystalline nature of the samples. The influence of the Bi(2)O(3) on the thermal, structural, and optical properties was investigated. Differential scanning calorimetry analysis showed that the glass transition temperature, T(g), increases from 405 to 440 °C for 0 ≤ x ≤ 15 mol % and decreases to 417 °C for x = 30 mol %. The thermal stability against devitrification decreases from 156 to 67 °C with the increase of the Bi(2)O(3) content. The structural modifications were studied by Raman scattering, showing a bismuth insertion into the phosphate chains by Bi-O-P linkage. Furthermore, up to 15 mol % of Bi(2)O(3) formation of BiO(6) clusters is observed, associated with Bi-O-Bi linkage, resulting in a progressive break of the linear phosphate chains that leads to orthophosphate Q(0) units. The linear refractive index, n(0), was measured using the prism-coupler technique at 532, 633, and 1550 nm, whereas the nonlinear (NL) refractive index, n(2) was measured at 1064 nm using the Z-scan technique. Values of 1.58 ≤ n(0) ≤ 1.88, n(2) ≥ 10(-15) cm(2)/W and NL absorption coefficient, α(2) ≤ 0.01 cm/GW, were determined. The linear and NL refractive indices increase with the increase of the Bi(2)O(3) concentration. The large values of n(0) and n(2), as well as the very small α(2), indicate that these materials have large potential for all-optical switching applications in the near-infrared.

Near-infrared Kerr nonlinearity of Pb(PO3)(2)-WO3 glasses

We report measurements of the nonlinear refractive index, n2, and the nonlinear absorption coefficient, α2, of Pb(PO3)2–WO3 glasses. The measurements were performed using 100 fs (17 ps) laser pulses at 800 nm (1064 nm). Positive values of n2∼10−19 m2/W and negligible α2 were measured. The results show that the nonlinearity is faster than 100 fs and it is observed an increase of n2 with the increasing of the WO3 amount in the samples. The Boling, Glass, and Owyoung model, based on the semiclassical harmonic oscillator model, was used to predict the values of n2, with basis on the values of the linear refractive index of the samples.

Structural investigation of nickel polyphosphate coacervate glass–ceramics

Nickel polyphosphate coacervates have been prepared through the coacervation process of sodium polyphosphate and Ni2+ chloride solutions by the addition of different solvents with low molecular weight. The great potential of nickel polyphosphate coacervates as a material precursor was demonstrated by preparation of nickel polyphosphate glass–ceramics. Structural and spectroscopic properties were analyzed by thermal analysis, X-ray powder diffraction, Raman spectroscopic and UV-VIS techniques. Raman spectra for the nickel polyphosphate coacervates and nickel polyphosphate coacervates glass–ceramics samples shows that the addition of solvents leads to a depolymerization of the polyphosphate chains, resulting in an increase of shorter chains species based on pyrophosphates. The identification and quantification of Ni2P4012, β-Ni2P2O7 and δ-Ni2P2O7 crystalline phases present in the nickel polyphosphate glass–ceramics were carried out by X-ray powder diffraction using the Rietveld method. Quantitative phase analyses of the three polymorph forms were also evaluated. Based on interpretation of reflectance spectroscopy and Rietveld refinement, Ni2+ ions may occupy distorted octahedral and tetrahedral sites.