Dysprosium-doped oxyfluoride glasses and nanocrystalline glass ceramics have been synthesized and studied by x-ray diffraction, absorption, and visible and near-infrared emission spectra. The samples emit intense white light when populating the F49/2 level with a 451 nm laser light and, from the visible emission spectra, yellow to blue intensity ratios and chromaticity color coordinates have been calculated and their relative variation have been discussed based on the concentration of Dy3+ ions and the heat treatment conditions used to prepare the glass ceramics. Infrared emission has also been observed in glasses and glass ceramics after laser excitation at 800 nm, showing bands at 1.33 and 1.67 μm, useful for optical amplification in fiber amplifiers.

The radiative emission properties of the Dy3+ ions in an oxyfluoride glass and glass-ceramics have been studied for the generation of white light. The x-ray diffraction pattern of the glass-ceramics shows the formation of CaF2 fluorite-type nanocrystals in the glass matrix after a suitable thermal treatment of the precursor glass, whereas time-resolved optical measurements show the incorporation of the Dy3+ ions in the CaF2 nanocrystals. Intense white light has been observed when the samples are excited with 451 nm laser light. From the visible emission spectra, yellow to blue intensity ratios and the chromaticity color coordinates have been determined. All the color coordinates are found to lie in the white light region of the chromaticity color diagram.

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Thulium-doped metaphosphate glasses with four concentrations (0.01, 0.1, 1.0 and 2.0 mol%) of Tm 3+ have been prepared and investigated by Raman, absorption and photoluminescence spectral studies. The phonon sideband spectrum has been measured for 1.0 mol% Eu 3+ -doped metaphosphate glass of the same composition and compared with the Raman spectrum. From vibronic spectra, various bands associated with different structural groups have been identified and assigned. Absorption band positions have been used to simulate the complete energy level diagram for the Tm 3+ ion using the model Hamiltonian. Judd-Ofelt parameters have been determined from the absorption bands. Using these parameters, transition probabilities, excited state lifetimes and transition branching ratios have been evaluated. The emission and decay curves of the 1 D 2 level have been measured for all four glass samples both at RT and 15 K. Lifetimes show a strong quenching for Tm 3+ concentrations higher than 0.1 mol%. Fluorescence decay curves of the 1 D 2 level have been well fitted to the Inokuti-Hirayama model for S = 6, suggesting that the mechanism for energy transfer between Tm 3+ ions is of dipole-dipole type.

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