Spectroscopic investigation of 2.02 μm emission in Ho3+/Tm3+ codoped transparent glass ceramic containing CaF2 nanocrystals

Abstract

Tm 3 + and Ho3+ codoped transparent glass ceramic (GC) containing CaF2 nanocrystals were fabricated by melt-quenching and subsequent thermal treatment. X-ray diffraction and transmission electron microscopy analysis confirmed the precipitation of CaF2 nanocrystals among the glass matrix. Energy-dispersive x-ray spectroscopy results evidenced the incorporation of Tm3+ and Ho3+ into the CaF2 nanocrystals. Judd–Ofelt parameters were calculated based on the absorption spectra, the smaller Ω2 and larger Ω6 imply that Tm3+ and Ho3+ ions has entered into a symmetrical ionic crystal field. 2.02 μm emission spectral of the GC samples were recorded at room temperature with an excitation of 808 nm laser diode. The enhancement of the emission at 2.02 μm in the GC samples could be attributed to more efficient cross relaxation process of Tm3+:H34+Tm3+:H36→2Tm3+:H34, and energy transfer from Tm3+ to Ho3+ benefited from the incorporation of rare earth ions into CaF2 nanocrystals.