Efficient white upconversion luminescence in Yb/Eu doubly-doped transparent glass ceramic.

Efficient white upconversion (UC) luminescence is obtained in Yb/Eu doubly-doped optical glass ceramic (GC) for the first time. KYbF nanocrystals are controllably precipitated from the amorphous networks via the inducing of Yb. Yb ions are spontaneously confined within the compact fluoride crystal structures to produce efficient blue UC emissions of Yb-Yb pairs. Eu ions are easily incorporated into the KYbF crystal lattices. Owing to the extremely short interionic distance in the crystal structures, intense green UC emissions apart from the red emissions of Eu are observed, which are not obtained by the traditional Yb/Eu doubly-doped GCs. As a result, white UC emissions are synthesized based on the three-primary-color principle and the emission intensities of GCs are dramatically enhanced as compared to glass. The designed GCs provide novel optical gain materials for the promising applications in three-dimensional display, solid-state lighting and tunable fiber lasers.