Efficient energy transfer between Er and Dy achieved in perfluoride glass ceramics by tailoring crystallization characteristics

Perfluoride glass ceramics (FGCs) with SrF2/CaF2 mixed crystals were prepared using a concurrent rapid-quenching-crystallization process. The FGCs contained dense, homogeneous, round crystals of sizes less than 1 μm with high transmittance (exceeding 80% at 3-8 μm) and low phonon energy (508 cm-1). The fluorescence properties of the FGCs doped with Er and Dy were investigated. The energy transfer efficiency between Er and Dy reached 93.81% and 98.13%, corresponding to Er: 4I11/2 to Dy: 6H5/2 and Er: 4I13/2 to Dy: 6H11/2, respectively. This enhancement is attributed to the enrichment of rare-earth ions in the crystals induced by phase-separation and low phonon energy of the host material, FGC. Moreover, the average lifetime of Er: 4I11/2 in FGC reached 10.13 ms, which is the highest reported value for glass ceramics to our knowledge. This study enriches the research theory of FGC and provides guidance for expanding the properties of materials for mid-infrared photonics.