Abstracts Category : Other

Upconversion in Erbium-doped transparent glassceramics

by Gina Christine Jones

Transparent glass ceramics (TGCs) are a class ofmaterials that are composed of a robust glass matrix which isdensely embedded with nanometersized fluoride crystals. In bulk,fluoride materials tend to have poor handling and mechanicalproperties, and can be expensive to produce. In contrast, theforming and handling properties of the TGC are similar to those ofthe precursor glass, and are engineered to be robust andmechanically stable. Rare earth ions can be incorporated into theTGC during manufacture and can become partially segregated into thecrystalline phase. There they experience the low-phonon energyenvironment of the fluoride nanocrystallite, which induces longenergy level lifetimes and enhanced frequency upconversion.Therefore, rare earth doped TGCs can have the spectroscopicproperties of a crystal with the durability of an aluminosilicateglass. </br>Upconversion fluorescence is studiedfor an aluminosilicate TGC containing LaF nanocrystallites anddoped with an erbium density of 1.7 x 10 cm. Time gatedfluorescence and excitation spectra as well as photoluminescencedecays are used to find the nature and origin of this fluorescence.It is determined that energy transfer upconversion occurs only inthe nanocrystallite phase and sequential two-photon absorptionupconversion occurs in both glass and crystalphases.