Spectroscopic studies of Pr3+ doped lithium lead alumino borate glasses for visible reddish orange luminescent device applications

Lithium Lead Alumino Borate (LiPbAlB) glasses doped with Pr3+ ions were prepared via melt quenching technique to study their luminescence behavior using absorption, excitation, photoluminescence (PL) and decay spectral studies. A broad hump observed in XRD confirms the amorphous nature of the as-prepared glass. The glass transition temperature (T-g) and thermal stability (Delta T) were measured from Differential Scanning Calorimetry (DSC). FT-IR and Raman studies were performed to understand the network functional groups involved in the host glass. Various radiative parameters for the prominent fluorescent levels of Pr3+ were evaluated with in the frame work of Judd-Ofelt theory. PL and confocal images recorded under 445 nm Continuous Wave (CW) diode laser excitation were used to understand the visible emission characteristic features of the as-prepared glasses. The decay profiles of D-1(2) -> H-3(4) show single exponential for lower concentration and non-exponential for higher concentration resulting decrease in experimental lifetime (tau(exp)) with increase in concentration. Such decrease in texp and decay conversion from single to non-exponential with increase in rare earth ion concentration has been attributed to the cross-relaxation processes and subsequent concentration quenching observed. From the emission cross-sections, branching ratios, quantum efficiency, CIE coordinates and confocal images, it was concluded that 1 mol % Pr3+ ion concentration is optimum in LiPbAlB glasses to develop visible reddish orange luminescent devices

Optical studies of Sm3+ ions doped Zinc Alumino Bismuth Borate glasses

Zinc Alumino Bismuth Borate (ZnAlBiB) glasses doped with different concentrations of samarium (Sm3+) ions were prepared by using melt quenching technique and characterized for their lasing potentialities in visible region by using the techniques such as optical absorption, emission and emission decay measurements. Radiative properties for various fluorescent levels of Sm3+ ions were estimated from absorption spectral information using Judd-Ofelt (JO) analysis. The emission spectra and con-focal photoluminescence images obtained by 410 nm laser excitation demonstrates very distinct and intense orange-red emission for all the doped glasses. The suitable concentration of Sm3+ ions in these glasses to act as an efficient lasing material has been discussed by measuring the emission cross-section and branching ratios for the emission transitions. The quantum efficiencies were also been estimated from emission decay measurements recorded for the (4)G(5/2) level of Sm3+ ions. From the measured emission cross-sections, branching ratios, strong photoluminescence features and CIE chromaticity coordinates, it was found that 1 mol% of Sm3+ ions doped ZnAlBiB glasses are most suitable for the development of visible orange-red lasers

Luminescence spectral studies of Tm3+ ions doped Lead Tungsten Tellurite glasses for visible Red and NIR applications

Lead Tungsten Tellurite (LTT) glasses doped with different concentrations of Tm3+ ions of composition (60 - x) TeO2+ 25WO(3)+ 15PbF(2)+xTm(2)O(3) (Here x=0.1, 0.5, 1.0, 1.5, 2.0, 2.5 mol%) were prepared by using melt quenching technique and characterized through optical absorption, photoluminescence and decay spectral studies to know the feasibility of using these glasses as luminescent devices in visible Red and NIR regions. Judd-Ofelt (J-O) theory has been applied to the optical absorption spectral profiles to calculate the J-O intensity parameters Omega(lambda),, (lambda=2, 4 and 6) and consecutively used to evaluate various radiative properties such as radiative transition probability (A(R)), radiative lifetimes (tau(R)) and branching ratios (beta(R)) for the prominent luminescent levels. The luminescence spectra for all the LTT glass samples have two intense peaks in bright red and near Infrared regions at 650 nm ((1)G(4)-> F-3(4)) and 800 nm (H-3(4)-> H-3(6)) respectively for which effective band widths (Delta lambda(P)), experimental branching ratios (beta(exp)) and stimulated emission cross-sections (sigma(se)) are evaluated. The decay profiles for all the glasses are recorded to measure the quantum efficiency by coupling the radiative with experimental lifetimes. From the measured emission cross-sections, quantum efficiency and CIE chromaticity co-ordinates, it was found that 0.5 mol% of Tm3+ ions doped LTT glass is most suitable for generating bright visible Red and NIR lasers to operate at 650 and 800 nm respectively

Pr3+ doped lead tungsten tellurite glasses for visible red lasers

Lead tungsten tellurite (LTT) glasses doped with Pr3+ (0.01, 0.1, 0.5, 1.0 and 1.5 mol%) ions were prepared by the conventional melt quenching technique. The glasses were characterized by X-ray diffraction, optical absorption and photoluminescence spectra. The glassy nature of LTT host glass has been confirmed through XRD measurements. From the measured intensities of various absorption bands of these glasses, the three phenomenological Judd Ofelt (1-0) intensity parameters (Omega 2, Omega 4 and Omega 6) have been evaluated by using the standard as well as modified J-O theory. The J-O parameters measured from the modified J-O theory were used to characterize the absorption and luminescence spectra of these glasses. From this theory, various radiative properties like radiative transition probability (A(R)), total transition probability (A(T)), branching ratio (ss(R)) and radiative lifetime (tau(R)) have been evaluated for the fluorescent levels of Pr3+ in these glasses. The emission spectra show five emission bands in visible region for which the effective band widths (Delta lambda(p)) and emission cross-sections (sigma(se)) have been evaluated. Among all the five emission transitions, a transition P-3(0)-> F-3(2) is more intense and falls in red region. The visible emission spectra, stimulated emission crosssections and branching ratios observed for all these glasses suggest the feasibility of using these glasses as lasers in red region. The CIE chromaticity co-ordinates were also evaluated from the emission spectra to understand the suitability of these materials for red emission. From the absorption, emission and CIE chromaticity measurements, it was found that 1 mol% of Pr3+ ion concentration is quite suitable for LTT glasses to develop bright red lasers from these glasses