Heat-Induced Emission Enhancement in a Yb:YAG Crystal-Derived Silica Fiber

Abstract

We fabricated a Yb:YAG crystal-derived silica fiber (YCDSF) by the melt-in-tube method with a CO2 laser-heated drawing tower and explored the influences of the heat treatment method on fluorescent properties in the YCDSF. After the heat treatment, the intensity of the emission peaks and the fluorescence lifetime of the YCDSFs improved. In particular, after 1350 °C of heat treatment, a series of sharp peaks appeared in the core layer, which may form a new crystalline phase. Moreover, its emission intensity at 1030 nm was significantly enhanced, over 2 times greater than before the heat treatment. Additionally, the fluorescence lifetime of Yb ions was also increased from 129 to 621 μs, indicating the changes in local environments around Yb ions. Then, schematic models were set up to show how the local environments around Yb ions are gradually changing. These results revealed that the assessed YCDSF is of excellent performance; after the heat treatment, it may be a potential material for realizing optical amplification, light sources, fiber lasers, and so on.