White light generation in Dy3+-and Ce3+/Dy3+-doped zinc-sodium-aluminosilicate glasses

A spectroscopic investigation of 1% Dy<inf>2</inf>O<inf>3</inf>-singly doped and 0.5% Ce<inf>2</inf>O<inf>3</inf>-1.0% Dy<inf>2</inf>O<inf>3</inf>-codoped zinc-sodium-aluminosilicate glasses was performed by analyzing their absorption and photoluminescence spectra, and decay times. Warm white yellow light emission, with (0.419, 0.440) CIE1931 chromaticity coordinates and 3579 K color temperature, is obtained in the Dy³⁺-singly doped glass excited at 399 nm, which fits to the requirements of GaN LEDs. A quantum efficiency of 74% and a very high optical gain (38.7×10^-25 cm² s) were estimated for the dysprosium ⁴F<inf>9/2</inf> level luminescence, which might also make the Dy³⁺-doped glass a promising gain medium for solid state yellow laser pumped by GaN LEDs. In the Ce³⁺/Dy³⁺-codoped glass a radiative energy transfer from Ce³⁺ to Dy³⁺ is observed upon UV excitation (310-365 nm), with a Ce³⁺ to Dy³⁺ interaction distance that could be greater than 6-12 Å. The emission color from the codoped glass can be tuned with the excitation wavelength from blue light (0.247, 0.245), upon 310 nm excitation, to cold white light (0.284, 0.300), with a 9052 K color temperature, upon 365 nm excitation.