White light generation in Dy 3+ -and Ce 3+ /Dy 3+ -doped zinc–sodium–aluminosilicate glasses

A spectroscopic investigation of 1% Dy2O3-singly doped and 0.5% Ce2O3-1.0% Dy2O3-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 3579K color temperature, is obtained in the Dy3+-singly doped glass excited at 399nm, which fits to the requirements of GaN LEDs. A quantum efficiency of 74% and a very high optical gain (38.7×10−25cm2s) were estimated for the dysprosium 4F9/2 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 (310–365nm), with a Ce3+ to Dy3+ interaction distance that could be greater than 6–12Å. The emission color from the codoped glass can be tuned with the excitation wavelength from blue light (0.247, 0.245), upon 310nm excitation, to cold white light (0.284, 0.300), with a 9052K color temperature, upon 365nm excitation.