Enhanced 2.0 μm emission in oxyfluoride glass-ceramics containing nanocrystals MF_2 (MF_3): Ho~(3+),Tm~(3+) (M = Ca, Ba, and La)

摘要

Transparent glass-ceramics containing MF_2(MF3): Ho~(3+),Tm~(3+) (M = Ca, Ba, and La) nanocrystals have been prepared by melt quenching and subsequent thermal treatment. X-ray diffraction and transmission electron microscopy analysis confirmed the precipitation of MF_2 (MF_3) nanocrystals among the glass matrix. Energy-dispersive X-ray spectroscopy results evidenced the incorporation of Tm~(3+) and Ho~(3+) into the MF_2 nanocrystals. Intense 2.0 μm emission originating from the Ho~(3+): ~5I_7 → ~5I_8 transition was achieved upon excitation with 808 nm laser diode. A large ratio of the forward Tm~(3+) → Ho~(3+) energy transfer constant to that of the backward process indicated high efficient energy transfer from Tm~(3+) (3F4) to Ho~(3+) (~5I_7), and benefited from the reduced ionic distances of Tm~(3+)-Tm~(3+) and Tm~(3+)-Ho~(3+) pairs and low phonon energy environment with the incorporation of rare earth ions into the precipitated MF2 nanocrystals. The results indicate that oxyfluoride glass-ceramic is a promising candidate for 2.0 μm laser.