Intense yellow luminescence from Dy-doped TeO-WO-GeO glasses: structural and optical characterization.

Different concentrations of Dy-doped oxyfluoride tellurite (TWGDy) glasses of composition (85  -  x) TeO  +  5 WO  +  10 GeO  +  x DyF, where x  =  0, 0.1, 0.5, 1.0 and 2.0 mol% were prepared by melt quenching method. The Judd-Ofelt theory was applied to study the luminescence properties. Three phenomenological Judd-Ofelt (Ω ) intensity parameters were obtained as Ω  =  4.90  ×  10 cm, Ω  =  1.73  ×  10 cm and Ω  =  1.48  ×  10 cm for 0.5 mol% of Dy-doped TWGDy glass. When excited at different wavelengths, the TWGDy glasses exhibit three emission bands due to F  →  H (blue), F  →  H (yellow) and F  →  H (red) transitions. The excitation wavelength was optimized as 453 nm for strong and proficient luminescence from TWGDy glasses. Beyond 0.5 mol% of Dy concentration, the TWGDy glasses show luminescence quenching. The laser characteristic parameters such as effective bandwidth, stimulated emission cross-section, gain bandwidth and optical gain were determined using the emission spectra and radiative parameters. The 0.5 mol% of Dy-doped TWGDy glass could be potential to design a new class of yellow laser material.