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1

Thermal treatment effect on dynamics of luminescent states in oxyfluoride glass-ceramics doped with Pr3+ and Tb3+

Dominiak-Dzik G., Klimesz B., Ryba-Romanowski W.

Optica Applicata

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2010

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Vol. 40, nr 2

375--382

EN

The 50GeO2–(50–x–y)PbO–yPbF2–xLnF3 glass single doped with Pr3+ and Tb3+ ions was studied. The composition of the material was modified by varying the content of both PbF2 (y = 5, 10, 15 mol%) and LnF3 (x = 0.2 and 2 mol%). The differential thermal analysis (DTA) of as-melted samples was used to determine thermal characteristics. Optical techniques and kinetics measurements were used to monitor the effect of thermal treatment on spectroscopic properties and dynamics of luminescent states of optically-active ions in amorphous and two-phase systems. It was found that non-exponential decays of praseodymium luminescence in as-melted material become exponential or nearly exponential with corresponding longer lifetimes in thermally-treated samples. This effect was not so strong in the Tb3+-doped glass. The influence of the PbF2 content on luminescence dynamics was studied for samples doped with 2 mol% of Pr3+. It was observed that the increase of PbF2 content leads to lengthening of luminescence lifetime, e.g., the 1D2 lifetime increases from 4.1 to 45 ?s in 5 and 15 mol% of PbF2 as-melted samples, respectively.

2

Influence of PbX2 (X = F, Cl, Br) content and thermal treatment on structure and optical properties of lead borate glasses doped with rare earth ions

Pisarska J., Lisiecki R., Dominiak-Dzik G., Ryba-Romanowski W., Goryczka T., Grobelny Ł., Pisarski W. A.

Optica Applicata

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2010

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Vol. 40, nr 2

351--358

EN

Oxyhalide lead borate glasses doped with rare earth ions have been studied before and after thermal treatment. The rare earths as optically active ions were limited to the Er3+ ions. Near-infrared luminescence due to the main 4I13/2–4I15/2 laser transition of Er3+ was registered. The introduction of PbX2 to the borate glass results in a reduction of spectral linewidth and an increase of luminescence lifetime of 4I13/2 state of Er3+ ions. The unusual large spectral linewidth for 4I13/2–4I15/2 transition of Er3+ in the oxide glass host was obtained, whereas the luminescence decay from 4I13/2 state is longer for a sample with PbF2 than PbCl2 and PbBr2. Heat treatment introduces transformation from a glass to transparent glass-ceramic (TGC). The coordination sphere around Er3+ ions is changed, giving important contribution to the luminescence characteristics. The spectroscopic consequence of this transformation is the increase of luminescence lifetime and the narrowing of spectral lines of Er3+.

3

Near-infrared luminescence of rare earth ions in oxyfluoride lead borate glasses and transparent glass-ceramic materials

Pisarska J., Ryba-Romanowski W., Dominiak-Dzik G., Goryczka T., Pisarski W.A.

Optica Applicata

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2008

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Vol. 38, nr 1

211-216

EN

Oxyfluoride lead borate glasses singly doped with Nd3+ and Er3+ ions have been studied before and after thermal treatment. The orthorhombic PbF2 crystallites are formed during thermal treatment, which was evidenced by X-ray diffraction analysis. Near-infrared luminescence spectra at 1.06 žm and 1.53 žm have been registered for samples before and after annealing, which correspond to the main 4F3/2-4I11/2 and 4I13/2-4I15/2 laser transitions of Nd3+ and Er3+ ions, respectively. Luminescence decays from 4F3/2 state of Nd3+ and 4I13/2 state of Er3+ have been analyzed in detail. Contrary to Nd-doped samples, the luminescence lines obtained for Er-doped transparent oxyfluoride glass-ceramics are more intense and narrowed, whereas the luminescence decays from 4I13/2 state of Er3+ are slightly longer in comparison to precursor glasses.

4

Nd3+ or Sm3+ doped oxyfluoride glass based on GeO2-PbO-PbF2. Synthesis and spectroscopic properties

Klimesz B., Dominiak-Dzik G., Ryba-Romanowski W.

Optica Applicata

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2005

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Vol. 35, nr 4

843-850

EN

Glasses with composition 50 GeO2-(45 - x)PbO-5 PbF2-x LnF3 (Ln = Nd or Sm, x = 0.2 and 2 mol%) were synthesised in the bulk form. Phase profiles and temperature characteristics were measured by differential thermal analysis (DTA); glass transition temperature Tg, as well as the b-PbF2 Tb and oxide glass crystallisation Tc temperatures have been derived for each individual system. A study of optical properties (absorption, emission) of the PbF2-Nd3+ and PbF2-Sm3+ was carried out. The oscillator strengths were obtained for several optical transitions and they have been used to calculate phenomenological intensity parameters W2, 4, 6. The probabilities of radiative transitions from fluorescent levels of Nd3+ and Sm3+ ions, as well as branching ratios and radiative lifetimes, were estimated on the basis of the Judd-Ofelt framework. The fluorescence dynamics of studied systems was measured. Experimental lifetimes were compared and discussed with those obtained with the Judd-Ofelt theory.

5

Energy transfer from Yb to X (X = Tm, Er) in lead borate glasses

Pisarska J., Ryba-Romanowski W., Dominiak-Dzik G., Goryczka T., Pisarski W.A.

Optica Applicata

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2005

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Vol. 35, nr 4

837-842

EN

Energy transfer processes in lead borate glasses doubly doped with Yb-Tm and Yb-Er have been investigated at room temperature under excitation of Yb at 975 nm. The non-resonant energy transfer from 2F5/2 state of Yb to 3H5 state of Tm results in up-converted emission at 850 nm due to the 3H4-3H6 transition of thulium ions. The nearly resonant transfer from 2F5/2 state of Yb to 4I11/2 state of Er results in green up-conversion and near-infrared emission, which correspond to the 4S3/2-4I15/2 and 4I13/2-4I15/2 transitions of erbium ions, respectively. High Yb concentration in both co-doped samples is required for optimal energy transfer efficiency (h > 90%). Results with the singly Yb-doped samples are also presented to clarify the energy transfer process.

6

Optical absorption and luminescence of LiTaO₃:Cr and LiTaO₃:Cr, Nd crystals

Gołąb S., Sokólska I., Dominiak-Dzik G., Palatnikov M. N., Sidorov N. V., Biryukova I., Kalinnikov V. T., Ryba-Romanowski W.

Opto-Electronics Review

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1999

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Vol. 7, No. 2

145-147

EN

The interest in LiNbO₃ and LiTaO₃ crystals doped with transition metal or rare eartch ions is related to their potential applications as self-switching and self-frequency doubling laser materials. In the past considerable attention has been paid to LiNbO₃ crystals doped by variety of luminescent ions. In particular LiNbO₃:Cr was investigated recently by Macfarlane et al. [1]. Energy transfer between Cr³⁺ and Nd³⁺ in LiNbO₃ has been studied and discussed by Vergara et al. [2]. In this work we investigate spectroscopic properties of Cr³⁺ and Cr³⁺ - Nd³⁺ interaction in LiTaO₃ using optical absorption, luminescence and luminescence decay times at temperatures between 5 K and 300 K. Some preliminary data obtained with singly doped LiTaO₃:Cr at low activator concentration are given in our previous work [3]. Recorded spectra indicate that both the Cr³⁺ and Nd³⁺ are located in several non - equivalent sites that differ in the strength of the crystal field. Luminescence spectrum of Cr³⁺ consists of a broad band whose maximum and intensity depend on temperature. Below about 50 K an additional sharp band with four distinct components appears in the spectrum. The broad band attributed to the spin allowed ⁴T₂ - ⁴A₂ transition of Cr³⁺ ions overlaps two absorption bands of Nd³⁺ ions at about 810 nm and 890 nm making the Cr³⁺ - Nd³⁺ energy transfer process feasible. Results of measurements are discussed and compared to those obtained with LiNbO₃:Cr.