The Preparation And Investigation Of Er³⁺-doped Oxyfluoride Glass Ceramics For 2.7 μm Mid-infrared Fluorescence

In recent years, 2-5 μm mid-infrared lasers have attracted great attentions due to its potential applications in various fields including remote sensing, atmosphere monitoring, medical surgery and so forth. Conventional researches for such mid-infrared lasers mainly focus on rare-earth doped glass or crystals. However, they suffer significant low fluorescent efficiency and poor machinability. Glass ceramics combine the advantage of both crystal and glass with excellent optical and mechical properties, opening up a new world for rare-earth based hsot materials. In present work, Er3+-doped transparent oxyfluoride glass ceramics were studied, with emphasize on its Er3+ 2.7 μm emission.Firstly, Silicate glass was chose for the glass host and Ca F2 is the crystal phase for this glass ceramics. XRD and TEM results demonstrated that Er3+: Ca F2 nanocrystals were successfully embedded the silicate glass ceremics after heat-treatment. An intense 2.7 μm emission due to Er3+: 4I11/2â†'4I13/2 was achieved upon the excitation of 980 nm laser diode.The transitions of rare earth at the wavelength of mid-infrared are sensitive to its host. To further improving the 2.7 μm fluorescent efficiency, the glass matrix as well as its crystal phase in the glass ceramics are redesigned. Gemanate glass with lower phonon energy and higher transparency at the wavelength of 3 μm is taken into consideration. La F3 with higher rare-earth solution is chose to be the crystal phase. The intensity of 2.7 μm emission detected from Er3+:La F3 embedded germanate glass was almost 2.5 times stronger than that of Er3+:Ca F2 embedded silicate glass. Due to the improvement of 2.7 μm fluorescence, the fluorescent lifetime of upper 4I11/2 level is also successful detected. It found that the fluorescent lifetime of upper 4I11/2 level is longer than that of lower 4I13/2 level. Based on these results, a systematical circulatory energy transfer mechanism is proposed to demonstrate the energy transfer between adjacent Er3+ ions.Based on the excellent luminence of Er3+: La F3 nanocrystals embedded geramante glass ceramics, Yb3+ and Ho3+ ions are introduced to the glass ceramics as sensitizers for Er3+ respectively. XRD results indicated that both Er3+/Yb3+ and Er3+/Ho3+ codoped samples are remain pure La F3 phase after heat-treatment. The Er3+: 2.7 μm emission are obviously improved at both Er3+/Yb3+ and Er3+/Ho3+ codoped samples with emission band broden. An emission band at around 2.9 μm is also observed at the Er3+/Ho3+ codoped samples due to Ho3+: 5I6â†'5I7.