Structural, thermal, and luminescent properties of germanate glass containing heavily Dy2O3 content

Abstract

The structural, thermal, and luminescent properties of germanate glass containing heavily Dy2O3 content are systematically investigated by means of differential scanning calorimetry, X-ray diffraction, Raman spectra, absorption and emission spectra, and dynamic lifetime decay curves. To seek a suitable composition, the optimal glass forming region is first predicted through the thermodynamic calculation method and their basic physical properties are further forecasted according to the phase diagram model. The experiment results show that the density, refractive index, characteristic temperature, and phonon energy of the glass host all exhibit a close connection with the rare earth concentration. Strikingly, when the amount of Dy2O3 is up to 10.5 mol%, the transition temperature of the glass reaches 747 °C, which is higher than any other known germanate glass and is much advantageous to achieve a higher laser damage threshold. Moreover, the high doping caused the refractive index to increase significantly, which also prompted the glass to obtain a larger emission section and quality factor, increasing the possibility of laser output. Besides, three visible luminescence peaks of Dy3+ at 480 nm (blue) and 575 nm (yellow), and 665 nm (red) are observed even at an extremely high Dy3+ concentration. All the results demonstrate that this kind of germanate glass containing significant amounts of RE could be of interest for implementation of high-gain fiber lasers.