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Journal of Alloys and Compounds. 01/2011;
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Journal of Alloys and Compounds. 01/2011; 509:4743 - 4747.
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International Journal of Applied Glass Science. 01/2011; 2:215-221.
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Journal of Quantitative Spectroscopy & Radiative Transfer. 01/2011; 112:78-84.
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Journal of Rare Earths. 01/2010; 28(2):189 - 193.
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International Seminar on Science and Technology of Glass Materials (ISSTGM-09), Acharya Nagarjuna University, Guntur, Andhra Pradesh, India; 01/2009
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IOP Conf. Series: Materials Science and Engineering. 01/2009; 2:012049 (1-5).
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IOP Conference Series: Materials Science and Engineering. 01/2009; 2:012049 (1-5).
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ABSTRACT: Nd3þ doped H3BO3–PbO–TeO2–RF (R ¼ Li, Na and K) glasses were prepared through melt quenching technique. Optical absorption and near infrared (NIR) fluorescence spectra were recorded at room temperature. The spectral intensities were analyzed in terms of the Judd–Ofelt (J–O) parameters (Ul¼ 2, 4, 6). The covalency effect of Nd–O bond on the J–O parameters was estimated from the relative absorbance ratio (R) between 4I9/2/4F7/2 and 4I9/2/4S3/2 transitions. The effect of Nd–O covalency on
the U4 and U6 intensity parameters as well as on the spontaneous emission probabilities (AR) was discussed. Lomheim and Shazer hybrid method was applied to determine the fluorescence branching ratios (bR) of each emission transition from the 4F3/2 metastable level to its lower lying levels. The evaluated total radiative transition probabilities (AT), stimulated emission cross-sections (se) and gain bandwidth parameters (se � DlP) were compared with the earlier reports.
Solid State Sciences. 01/2009; 11:2093.
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ABSTRACT: Optical absorption, luminescence and lifetime measurements of Sm(3+)-doped alkali fluorophosphate glasses with molar compositions of 50(NaPO(3))(6)+10TeO(2)+20AlF(3)+19RF+1Sm(2)O(3) (R=Li, Na and K) are described. The variation of optical properties with glass composition plays a dominant role in the determination of efficient laser materials. From the experimental oscillator strengths of f-f electric dipole transitions, the phenomenological Judd-Ofelt parameters have been evaluated and are used to evaluate radiative parameters such as radiative transition probabilities (A(R)), branching ratios (beta(R)), lifetimes (tau(R)) and integrated absorption cross-section (sigma(a)) for various excited levels. The predicted values of tau(R) and beta(R) from the (4)G(5/2) excited level to its lower levels are compared with the experimentally measured values. Stimulated emission cross-sections (sigma(e)) were also determined for (4)G(5/2)-->(6)H(J) (J=5/2, 7/2, 9/2 and 11/2) emission transitions. From the emission transitions of Sm(3+) in these alkali tellurofluorophosphate glasses certain potential laser transitions have been identified.
Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 08/2006; 64(4):939-44. · 2.10 Impact Factor
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Physica B: Condensed Matter. 01/2004; 352:210.
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ABSTRACT: A systematic study of the optical absorption and luminescence spectra of Er3+-doped alkali fluorophosphate glasses (RTFP) 50(NaPO3)–10TeO2–20AlF3–19RF–1Er2O3 (R = Li, Na and K) has been performed. The phenomenological Judd–Ofelt intensity parameters have been determined from the spectral intensities of the absorption bands in order to calculate the radiative transition probabilities, radiative lifetimes and branching ratios for various excited luminescent states. Using the visible and near infrared emission spectra, full width at half maximum (FWHM), emission cross-sections (σe) and figure of merit (FOM) were evaluated and compared with other hosts. Especially, the numerical values of these parameters indicate that the emission transition 4I13/2 → 4I15/2 transition at 1.534 μm in Er3+-doped fluorophosphate glasses may be highly useful in optical communication. The decay characteristic of 4S3/2 excited level has also been recorded and analyzed. The calculated and experimental lifetimes were compared in terms of quantum efficiencies and multiphonon relaxation rates.
Journal of Non-Crystalline Solids 353:1392-1396. · 1.54 Impact Factor
