W.J. Zhang

Near-infrared quantum splitting in Ho 3+ :LaF 3 nanocrystals embedded germanate glass ceramic

We report on a sequential two-step near-infrared quantum splitting in Ho3+-doped germanate glass ceramics (GC). The formation of LaF3 nanocrystals is confirmed by X-ray diffraction and transmission electron microscopy analysis. Emission of two NIR photons at 1013 and 1190 nm for one incident photon absorption within the 300-560 nm region has been demonstrated by static and dynamic photoemission and excitation spectroscopy. Using the spectroscopic parameters calculated from Judd-Ofelt theory, the quantum efficiency of Ho3+ in GC sample is estimated to be approximately 110%.

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

Tm3+ 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.