Upconversion Luminescence In Glass Research Articles

A comparative investigation on upconversion luminescence in glass–ceramics containing LaF3 and CaF2 nanocrystals

Greater enhancement in upconversion (UC) luminescence was observed in the glass–ceramics (GCs) containing CaF2:Yb3+, Er3+ nanocrystals (NCs) compared with whose doped with LaF3:Yb3+, Er3+ NCs prepared by conventional melt-quenching technique followed by successive heat treatment. Our joint experimental and theoretical studies suggest the lager enhancement of UC emission in CaF2–GCs rather than of LaF3–GCs is associated with the difference in the microstructures, the crystal size, the local coordination environment around rare earth (RE) ions as well as the structural rigidity in the silicate region of the GCs. In addition, it was found that a more symmetric ligand field around RE ions in a smaller size crystal which distributed more homogeneously within the highest ordering silicate region favors stronger UC emission by facilitating the energy transfer process and minimizing the rate of non-radiative relaxation process. Our results may enrich our understanding about UC process in oxyfluoride GCs and provide a general picture for the photophysical processes that contribute to the UC in similar GCs systems.

High upconversion optical gain of Er3+-doped tellurite glass

The upconversion technique of rare-earth-doped glasses or crystals is a potential route for achieving short-wavelength lasers (SWLs). The optical gain is an important parameter for evaluating lasing medium performance. Therefore, upconversion luminescence in glass with composition of 70TeO2–9PbF2–10AlF3–10BaF2–1Er2O3 was demonstrated, and the small-signal optical gain was measured via an amplified spontaneous emission technique when the sample was excited with a 980 nm laser. It was found that the optical gain was as large as 4.0 dB/cm, thus indicating that this glass may be a good medium for SWLs.