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Excitation and emission spectra of Pr 3+ :PLZT ceramics have been studied. Several emission bands were measured under blue laser excitation, which correspond to 3 P 0 → 3 H 4 , 1 D 2 → 3 H 4 , 3 P 0 → 3 H 4 and 3 P 0 → 3 F 2 transitions of trivalent Pr 3+ . Their integrated emission intensities were determined. The blue-to-red luminescence intensity ratios of Pr 3+ depend significantly on free sintering/hot pressing methods used for PLZT fabrication and activator concentration. Luminescence decay curves for the 1 D 2 state of Pr 3+ :PLZT ceramics are also presented and discussed. [ABSTRACT FROM AUTHOR]

In this paper, we report on fabricating optical fibers with a controlled process of crystallization core during the drawing process. The research and synthesis of the core material of silica-germanium-antimony oxide glass were discussed. We also investigated the optical and luminescence properties were in relation to concentrating Eu 2 O 3 and P 2 O 5. Based on this investigation, we selected the most promising material for optical fiber core. In the next step, we drew optical fibers using a well-known rod-in-tube method. After drawing, we examine the optical fibers for luminescence shape changes. We observed a promising similarity between optical fibers and heat-treated samples with confirmed nanocrystals. Finally, XRD and TEM measurements confirm EuPO 4 nanocrystals at the core of the optical fiber. Highlighting the successful control of crystallization in the one-step method used to draw optical fibers. [ABSTRACT FROM AUTHOR]

In this study, a comprehensive analysis of emission in erbium-doped and erbium and ytterbium co-doped fluoroindate glasses has been presented. The luminescence of the erbium transitions and the effect of ytterbium co-doping under 488, 808 and 976 nm laser excitation have been discussed. Optimization of rare-earth (RE) ions doping concentration and the energy transfer processes related to the sensibilization effect in Er3+/Yb3+ co-doped fluoroindate glasses focusing on the reciprocal distribution of radiative transitions, energy transfer parameters, and lifetimes have been analyzed. The luminescence consists of several bands in the visible (525, 546 and 660 nm) and the infrared (1550 and 2700 nm) spectral regions that correspond to characteristic radiative energy transitions within the erbium ions. In glasses co-doped with the Er3+/Yb3+ system, an augmentation in the emission intensity was observed in the visible and at 1550 nm, while a decrease was observed in the 2700 nm infrared band. The increase of the Yb3+: 2F 5/2 lifetime under 488, 808 and 976 nm excitation showed significant Er3+: 4I 11/2 → Yb3+: 2F 5/2 back energy transfer. Based on the analysis of the available literature, it can be concluded that energy transfer upconversion and cooperative energy upconversion play a significant role in modulating luminescence intensity values within the examined emission bands. This effect is likely enhanced due to the incorporation in a low phonon energy glass matrix. As a result of the above optimization, a glass optical fiber co-doped with 0.8 YbF 3 /1.4 ErF 3 (in mol%) was drawn and characterized, showing a strong emission at 2.77 μm. The optimized Er3+/Yb3+ co-doped fluoroindate glass and glass optical fiber confirmed their ability to be used in the visible and near-infrared spectral regions as efficient optical fiber sources. [ABSTRACT FROM AUTHOR]

In this work, Tm3+ doped and Tm3+/Ho3+ co-doped germanate glasses with various TiO 2 concentrations have been examined using optical spectroscopy. The broad emission bands corresponding to 3F 4 →3H 6 (1.8 μm) and 5I 7 →5I 8 (2 μm) transitions of thulium and holmium ions were registered, respectively. It was observed that the intensity of near-infrared emission bands significantly changes with increasing titanium oxide content in the glass composition. Furthermore, the energy transfer process from Tm3+ to Ho3+ ions in studied glass systems was confirmed and discussed. The dependence of spectroscopic parameters like full width at half maximum (FWHM) and energy transfer efficiency (η ET) on increased TiO 2 concentration in glass host was established. [ABSTRACT FROM AUTHOR]

In this contribution a comprehensive spectroscopic study of Dy3+ doped fluoroindate glass samples and glass fiber is presented. The mid-infrared (MIR) emission from DyF 3 doped bulk glass samples (0.2, 0.4, 0.8, 1.2, 1.4, 1.6 mol.%) is investigated when pumping at 1320 nm. A broadband mid-infrared emission spanning from 2800 nm to 3500 nm with 0.88 ms emission lifetime of the 6H 13/2 level in 0.2 mol.% glass sample was observed. Also 0.2 mol.% of DyF 3 doped fluoroindate glass fiber was drawn and its photoluminescence properties were studied showing the emission spectrum to 3500 nm and the 6H 13/2 level lifetime of 0.91 ms. The results obtained show that fluoroindate glass is a good candidate for further development of tunable fiber lasers and broadband mid-infrared spontaneous emission fiber sources. [ABSTRACT FROM AUTHOR]

This work presents an analysis of the spectroscopic properties of glass and glass ceramics co-doped with Ni2+ and Er3+ ions. Spectroscopic analysis showed the embedding of nickel ions in the gamma-gallium oxide nanocrystals as a result of heat treatment of the glass samples. Analysis of the luminescence properties of the obtained samples under 940 nm and 980 nm pump excitation allowed the selection of a proper Er3+ ions concentration for further optical fiber fabrication. Measured lifetime results of glass-ceramics samples confirm energy transfer from nickel ions to erbium. In the process of drawing the optical fiber, it was possible to create a transparent nanocrystalline glass-ceramic core, as confirmed by XRD results. The produced glass-ceramic optical fiber was characterized by broadband emission in the range from 1100 nm to 1650 nm corresponding to the 3T 2 (3F) →3A 2 (3F) (Ni2+) and 4I 13/2 → 4I 15/2 (Er3+) transitions for 940 nm and 980 nm pump excitation. The Er3+ to Ni2+ ions emission intensity ratio of the fabricated glass-ceramic fiber was estimated to be 0.84 and 7.14 for 940 nm and 980 nm optical pumps, respectively. [ABSTRACT FROM AUTHOR]

In this work, the series of silicate xerogels co-doped with Gd3+ and Eu3+ ions have been synthesized via a sol-gel method and further processed into nano-glass-ceramic materials. The mutual molar ratio of trivalent metal ions' acetates in samples' compositions was gradually modified as follows: La3+:Gd3+:Eu3+ = (0.95-x):x:0.05, x = 0.05, 0.25, 0.45, 0.65, and 0.90; hence the molar ratio of Gd3+:Eu3+ (R Gd/Eu) was set from 1 through 5, 9, 13 up to 18. XRD measurements confirmed the amorphous nature of fabricated xerogels, but their heat-treatment successfully triggered the crystallization of hexagonal LaF 3 fraction with an average size of about ∼10 nm, which was additionally confirmed by HR-TEM microscopy. Additionally, it was found that the LaF 3 phase crystallized in a whole range of proposed La(CH 3 COO) 3 :Gd(CH 3 COO) 3 molar ratio, and Gd3+ ions played only the role of dopant and replaced La3+ cation in the fluoride crystal lattice. The optical characterization of prepared sol-gel samples involved the registration of absorption, excitation and emission spectra, along with the luminescence decay analysis from the 6P 7/2 (Gd3+) and the 5D 0 (Eu3+) excited states. For nano-glass-ceramics defined by R Gd/Eu = 13 and 18, the unexpected prolongation of the τ(6P 7/2):Gd3+ lifetimes was denoted, compared with samples singly-doped with Gd3+. The changes in photoluminescence behavior of studied samples are strongly dependent on the nature of the fabricated sol-gel samples, the established molar ratios of La3+:Gd3+:Eu3+, and the tendency of cation-exchange in LaF 3 nanocrystal lattice by Gd3+ and Eu3+ ions. [ABSTRACT FROM AUTHOR]

This work reports on the analysis of structural and spectroscopic properties of the fluoroindate glasses co-doped with Er3+/Ho3+. Structural analysis showed that erbium and holmium ions were modifier ions and depolymerizedof the fluoroindate glass network. The energy transfer processes between rare - earth ions in fluoroindate glasses pumped by and 980 nm laser diode have been also examined. Due to partial Er3+ → Ho3+ energy transfer and superposition of Er3+: 4I 11/2 → 4I 13/2 (2.77 μm)+ Ho3+: 5I 6 → 5I 7 (2.85 μm) radiative transitions in fluoroindate glass co-doped with 0.8ErF 3 /1.6HoF 3 , a broadening 3 μm luminescence (Δλ= 201 nm) was obtained. The overall energy transfer efficiency η ET1 + η ET2 was calculated to be 95% indicating efficient sensitization of the holmium ions by erbium. [ABSTRACT FROM AUTHOR]

Nanocrystalline β-PbF 2 phase singly-doped with Eu 3+ and Tb 3+ ions have been successfully synthesized using sol-gel technique and subsequent heat-treatment of xerogels at 350 °C. Thermal behavior and structural properties of obtained materials were studied using thermogravimetric analysis (TG), differential scanning calorimetry (DSC) as well as FT-IR and Raman techniques. XRD results confirmed formation of β-PbF 2 nanocrystals embedded in silica amorphous hosts after annealing at 350 °C. Moreover, the photoluminescence properties have been investigated based on excitation and emission spectra as well as decay analysis from the 5 D 0 (Eu 3+ ) and the 5 D 4 (Tb 3+ ) excited states. The sharp intraconfigurational 4f 6 −4f 6 and 4f 8 −4f 8 emission transitions assigned as the 5 D 0 → 7 F J (J=0–4) of Eu 3+ and the 5 D 4 → 7 F J (J=6-3) of Tb 3+ bands, respectively, were registered. The most prominent bands in studied xerogels and glass-ceramic materials are related to the following electronic transitions: 5 D 0 → 7 F 1 (orange) and 5 D 0 → 7 F 2 (red) (Eu 3+ ) as well as 5 D 4 → 7 F 5 (green) and 5 D 4 → 7 F 6 (blue) (Tb 3+ ). Thus, the R/O (Eu 3+ ) and G/B (Tb 3+ ) luminescence intensity ratios were calculated and analyzed. Luminescence decay kinetic clearly indicated a presence of two different surroundings around Eu 3+ and Tb 3+ dopants in β-PbF 2 -based glass-ceramic samples. In such singly-doped with Eu 3+ and Tb 3+ materials, the longer luminescence lifetimes (Eu 3+ : τ 1 ( 5 D 0 )=0.90 ms, τ 2 ( 5 D 0 )=5.15 ms; Tb 3+ : τ 1 ( 5 D 4 )=0.48 ms, τ 2 ( 5 D 4 )=4.01 ms) of an appropriate excited states were achieved in comparison to xerogel hosts (Eu 3+ : τ( 5 D 0 )=0.38 ms; Tb 3+ : τ( 5 D 4 )=0.49 ms). The obtained results indicate the incorporation of Eu 3+ and Tb 3+ ions into nanocrystalline phase during ceramization process. [ABSTRACT FROM AUTHOR]

Luminescent properties of silica sol–gel nanomaterials doped with Tb 3+ ions were studied and the results are presented. Compositions of the studied materials were varied while the terbium ions concentration was kept constant. Some technological parameters were analyzed and their pronounced effect on the photoluminescence properties is observed. Spectroscopic parameters of Tb 3+ ions were determined basing on excitation and emission measurements as well as on luminescence decay analysis before and after heat treatment process. The registered emission bands in the visible spectral range correspond to the 5 D 4 → 7 F J ( J =3−6) transitions of Tb 3+ ions. Intensities of the emission bands and luminescence decay curves of Tb 3+ ions depend on the excitation wavelength. Also, enhancement of the emission bands intensities and a significant increase of luminescence lifetime for the 5 D 4 excited state of Tb 3+ ions after heat treatment process was observed. The structure of obtained glasses was examined using X-ray diffraction (XRD), as well as FT-IR and Raman spectroscopic techniques. The obtained results indicate the incorporation of Tb 3+ ions into nanocrystalline phase during ceramization process. [ABSTRACT FROM AUTHOR]

The effects of selective components M 2 O 3 (M=Al, Ga) on local structure, thermal and spectroscopic properties of lead phosphate glasses doped with Er 3+ ions were systematically investigated. It was found that the both oxide modifiers (Al 2 O 3 and Ga 2 O 3 ) may be classified as crystallizing agents for lead phosphate glass host. The glass transition temperatures for glass samples modified by M 2 O 3 were determined using differential scanning calorimetry. The X-ray diffraction analysis was used in order to verify the nature of lead phosphate - based systems. Near-infrared luminescence spectra corresponding to 4 I 13/2 → 4 I 15/2 transition of erbium ions were measured. The luminescence spectra of Er 3+ -doped lead phosphate glass are presented and discussed in relation to the impact of crystallizing agents M 2 O 3 (M=Al, Ga). Luminescence lifetimes for the upper 4 I 13/2 laser state of Er 3+ ions were also evaluated. [ABSTRACT FROM AUTHOR]

Abstract: Lead borate glasses were prepared and then heat treated in order to obtain transparent glass-ceramics. Controlled crystallization of precursor lead borate glass at appropriate annealing temperature and time led to formation of the PbWO4 crystallites. The observed broad blue emission band is related to the PbWO4 crystallites. The influence of PbX2 content (X=F, Cl, Br), PbF2 concentration and lanthanide doping (Eu, Dy) on the excitation and emission spectra of lead borate glass-ceramics containing PbWO4 phase was examined. The relationship between Pb–X bond and spectral line width of the blue emission can be successfully observed, when halogen X ions (X=F, Cl or Br) are also present in the distorted PbWO4 crystallites. [Copyright &y& Elsevier]